Information

Can hunting of large specimens of a species make the size and weight of the species tend to be smaller?


Siberian tigers in the wild don't grow as much as they used to be in past (in the 1900s). Their average weight was measured 176 kg in 2005 study. But it was also said that those tigers observed in study were sick and in conflict to humans.

I think their smaller size is because of low prey density because at that time, hunting of animals that come as tigers' prey was high.

Could it also be because all the large specimens were shot?


I don't know of any research about this on tigers or any other terrestrial predators, but this is a well-known phenomenon in "trophy" animals1 (i.e. big game hunted for sport) and wild-caught fish1-4.

1: Allendorf, F. W., & Hard, J. J. (2009). Human-induced evolution caused by unnatural selection through harvest of wild animals. Proceedings of the National Academy of Sciences, 106(Supplement 1), 9987-9994.

2: Heino, M., Pauli, B. D., & Dieckmann, U. (2015). Fisheries-induced evolution. Annual review of ecology, evolution, and systematics, 46.

3: Monk, C. T., Bekkevold, D., Klefoth, T., Pagel, T., Palmer, M., & Arlinghaus, R. (2021). The battle between harvest and natural selection creates small and shy fish. Proceedings of the National Academy of Sciences, 118(9).

4: Bowles, E., Marin, K., Mogensen, S., MacLeod, P., & Fraser, D. J. (2020). Size reductions and genomic changes within two generations in wild walleye populations: associated with harvest?. Evolutionary applications, 13(6), 1128-1144.


How Much Does a Rhino Weigh? (Species, Life Stages & Gender Differences)

Rhinoceros is Greek, meaning nose horned. The Rhinos are among the big five endangered species, and they live for around 30 to 45 years.

Both the male and female have horns, although the female’s front horn is often longer and thinner than the males in the white and black Rhinos.

So, how much do these animals weigh?

The white rhino is Africa’s largest species, also referred to as ‘square-lipped’ rhino.

Its habitat is in grassland and savanna, with a population of about 18,067. On its snout, it has two horns with the first longer than the other. It’s horns average about 90cm and can reach 150cm in length.

The gestation period is 16 months, and its calf weighs between 40 and 65 kg. An adult white rhino weighs approximately 1800 to 2700 kg and is found in Kenya, Uganda, Zambia, Botswana, South Africa, and Namibia.


Contents

The giant trevally is classified within the genus Caranx, one of a number of groups known as the jacks or trevallies. Caranx itself is part of the larger jack and horse mackerel family Carangidae, which in turn is part of the order Carangiformes. [3]

The giant trevally was first scientifically described by the Swedish naturalist Peter Forsskål in 1775 based on specimens taken from the Red Sea off both Yemen and Saudi Arabia, with one of these designated to be the holotype. [4] He named the species Scomber ignobilis, with the specific epithet Latin for "unknown", "obscure" or "ignoble". [5] It was assigned to the mackerel genus Scomber, where many carangids were placed before they were classified as a separate family. This later revision in classification saw the species moved to the genus Caranx, where it has remained. [6] Even after its initial description, the giant trevally (and the bigeye trevally) were often confused with the Atlantic crevalle jack, Caranx hippos, due to their superficial similarity, which led to some authors claiming the crevalle jack had a circumtropical distribution. [7] After Forsskål's initial description and naming, the species was independently renamed three times as Caranx lessonii, Caranx ekala and Carangus hippoides, all of which are now considered invalid junior synonyms. [8] The latter of these names once again highlighted the similarity with the crevalle jack, with the epithet hippoides essentially meaning "like Carangus hippos", [9] which was the crevalle jack's Latin name at that time. Despite the resemblance with the crevalle jack, the two species have never been phylogenetically compared, either morphologically or genetically, to determine their relationship.

C. ignobilis is most commonly referred to as the giant trevally (or giant kingfish) due to its large maximum size, with this often abbreviated to simply GT by many anglers. [10] Other names occasionally used include lowly trevally, barrier trevally, yellowfin jack (not to be confused with Hemicaranx leucurus), Forsskål's Indo-Pacific jack fish and Goyan fish. [6] In Hawaii, the species is almost exclusively referred to as ulua, often in conjunction with the prefixes black, white, or giant. [11] Due to its wide distribution, many other names for the species in different languages are also used. [6] In the Philippines, the species is referred to as talakitok. Some success has been achieved in raising giant trevally commercially in small fish farms there, typically to an age of seven months. [ citation needed ]

The giant trevally is the largest member of the genus Caranx, and the fifth-largest member of the family Carangidae (exceeded by the yellowtail amberjack, greater amberjack, leerfish and rainbow runner), with a recorded maximum length of 170 cm (67 in) and a weight of 80 kg (180 lb). [6] Specimens this size are very rare, with the species only occasionally seen at lengths greater than 80 cm (31 in). [12] It appears the Hawaiian Islands contain the largest fish, where individuals over 100 lbs are common. Elsewhere in the world, only three individuals over 100 lbs have been reported to the IGFA. [13]

The giant trevally is similar in shape to a number of other large jacks and trevallies, having an ovate, moderately compressed body with the dorsal profile more convex than the ventral profile, particularly anteriorly. The dorsal fin is in two parts, the first consisting of eight spines and the second of one spine followed by 18 to 21 soft rays. The anal fin consists of two anteriorly detached spines followed by one spine and 15 to 17 soft rays. [14] The pelvic fins contain 1 spine and 19 to 21 soft rays. [15] The caudal fin is strongly forked, and the pectoral fins are falcate, being longer than the length of the head. The lateral line has a pronounced and moderately long anterior arch, with the curved section intersecting the straight section below the lobe of the second dorsal fin. The curved section of the lateral line contains 58-64 scales, [15] while the straight section contains none to four scales and 26 to 38 very strong scutes. The chest is devoid of scales with the exception of a small patch of scales in front of the pelvic fins. [16] The upper jaw contains a series of strong outer canines with an inner band of smaller teeth, while the lower jaw contains a single row of conical teeth. The species has 20 to 24 gill rakers in total and 24 vertebrae are present. [12] The eye is covered by a moderately well-developed adipose eyelid, and the posterior extremity of the jaw is vertically under or just past the posterior margin of the pupil. [12] The eye of the giant trevally has a horizontal streak in which ganglion and photoreceptor cell densities are markedly greater than the rest of the eye. This is believed to allow the fish to gain a panoramic view of its surroundings, removing the need to constantly move the eye, which in turn will allow easier of detection of prey or predators in that field of view. [17]

At sizes less than 50 cm, the giant trevally is a silvery-grey fish, with the head and upper body slightly darker in both sexes. [18] Fish greater than 50 cm show sexual dimorphism in their colouration, with males having dusky to jet-black bodies, while females are a much lighter coloured silvery-grey. [18] Individuals with darker dorsal colouration often also display striking silvery striations and markings on the upper part of their bodies, particularly their backs. [10] Black dots of a few millimetres in diameter may also be found scattered all over the body, although the coverage of these dots varies between widespread to none at all. All the fins are generally light grey to black, although fish taken from turbid waters often have yellowish fins, with the anal fin being the brightest. [12] The leading edges and tips of the anal and dorsal fins are generally lighter in colour than the main part of the fins. There is no black spot on the operculum. [14] Traces of broad cross-bands on the fish's sides are occasionally seen after death. The fishes have been known to prey and eat on the dead fish. [19]

The giant trevally is widely distributed throughout the tropical and subtropical waters of the Bay of Bengal, Indian and Pacific Oceans, ranging along the coasts of three continents and many hundreds of smaller islands and archipelagos. [12] In the Indian Ocean, the species' westernmost range is the coast of continental Africa, being distributed from the southern tip of South Africa [20] north along the east African coastline to the Red Sea and Persian Gulf. Its range extends eastwards along the Asian coastline, including Pakistan, India and into Southeast Asia, the Indonesian Archipelago and northern Australia. [6] The southernmost record from the west coast of Australia comes from Rottnest Island, [21] not far offshore from Perth. Elsewhere in the Indian Ocean, the species has been recorded from hundreds of small island groups, including the Maldives, Seychelles, Madagascar and the Cocos (Keeling) Islands. [6]

The giant trevally is abundant in the central Indo-Pacific region, found throughout all the archipelagos and offshore islands including Indonesia, Philippines and Solomon Islands. Along continental Asia, the species has been recorded from Malaysia to Vietnam, but not China. [6] Despite this, its offshore range does extend north to Hong Kong, Taiwan and southern Japan. [12] [15] In the south, the species reaches as far south as New South Wales in Australia [21] and even to the northern tip of New Zealand in the southern Pacific. Its distribution continues throughout the western Pacific, including Tonga, Western Samoa and Polynesia, with its easternmost limits known to be the Pitcairn and Hawaiian Islands. [11] [16]

The giant trevally inhabits a very wide range of offshore and inshore marine environments, with the species also known to tolerate the low salinity waters of estuaries and rivers. It is a semipelagic fish known to spend time throughout the water column, but is mostly demersal in nature. [22] The species is most common in shallow coastal waters in a number of environments, including coral and rocky reefs and shorefaces, lagoons, embayments, tidal flats and channels. They commonly move between reef patches, often over large expanses of deeper sand and mud bottoms between the reefs. [23] [24] Older individuals tend to move to deeper seaward reefs, bomboras and drop-offs away from the protection of fringing reefs, often to depths greater than 80 m. [25] [26] Large individuals, however, often return to these shallower waters as they patrol their ranges, often to hunt or reproduce. [26] In Hawaii, the juvenile to subadult giant trevally is the most common large carangid in the protected inshore waters, with all other species apparently preferring the outer, less protected reefs. [27] It is also easily attracted to artificial reefs, where studies have found it to be one of the predominant species around these structures in Taiwan. [28]

Juvenile to subadult giant trevally are known to enter and inhabit estuaries, the upper reaches of rivers and coastal lakes in several locations, including South Africa, [29] Solomon Islands, [30] Philippines, [31] India, [32] Taiwan, [33] Thailand, [34] northern Australia, [35] and Hawaii. [23] In some of these locations, such as Australia, it is a common and relatively abundant inhabitant, [30] while in others, including South Africa and Hawaii, it is much rarer in estuaries. [23] The species has a wide salinity tolerance, as evident from the ranges from which juvenile and subadult fish in South African estuaries have been recorded 0.5 to 38 parts per thousand (ppt), [36] with other studies also showing tolerance levels of less than 1 ppt. [29] In these estuaries, the giant trevally is known from both highly turbid, dirty water to clean, high visibility waters, but in most cases, the species prefers the turbid waters. [23] Younger fish apparently actively seek out these turbid waters, and when no estuaries are present, they live in the turbid inshore waters of bays and beaches. These young fish eventually move to inshore reefs as they mature, before again moving to deeper outer reefs. [27]

In the Philippines, a population of giant trevally inhabit (and were once common in) the landlocked fresh waters of the formerly saltwater Taal Lake, and are referred to as maliputo to distinguish them from the marine variant (locally named talakitok). Along with Taal Volcano and Taal Lake, the maliputo is prominently featured on the reverse side of the newly redesigned Philippine 50 peso bill. [37]

The giant trevally is a solitary fish once it reaches sexual maturity, [20] only schooling for the purposes of reproduction and more rarely for feeding. [22] Juveniles and subadults commonly school, both in marine and estuarine environments. Observations from South African estuaries indicate the schools of smaller juveniles tend not to intermingle with schools of other species, but larger subadults are known to form mixed-species schools with the brassy trevally. [36] Research has been conducted on the movements of larger fish around their habitats, as well as the movement between habitats as the species grows, to understand how marine reserves impact on the species. Adult giant trevally are known to range back and forth up to 9 km along a home range, with some evidence of diel and seasonal shifts in habitat use. [26] In the Hawaiian Islands, giant trevally do not normally move between atolls, but have specific core areas where they spend most their time. Within these core areas, habitat shifts during different times of the day have been recorded, with the fish being most active at dawn and dusk, and usually shifting location near sunrise or sunset. [26] Furthermore, large seasonal migrations appear to occur for the purpose of aggregating for spawning, with this also known from the Solomon Islands. [38] Despite not moving between atolls, they do make periodic atoll-wide journeys of up to 29 km. [26] Long-term studies show juveniles can move up to 70 km away from their protected habitats to outer reefs and atolls. [24] The giant trevally is one of the most important apex predators in its habitats, both as adults on reefs and as juveniles in estuaries. [35] Observations in relatively untouched waters of the northwestern Hawaiian Islands showed the giant trevally was of high ecological importance, constituting 71% of the apex predator biomass, and was the dominant apex predator. This number is considerably less in heavily fished Hawaiian waters. [39] The species is prey to sharks, especially when small. Conversely, adult giant trevallies, either singles or pairs, have been recorded attacking sharks (like blacktip reef shark) by ramming them repeatedly with their head. The shark, sometimes even larger than the trevally, may die from the attack. The reason for this behavior is unclear, but the giant trevally does not attempt to eat the dead shark. Rarely, they have been recorded behaving in the same way towards humans: A spearfisher in Hawaii broke three ribs when rammed by a giant trevally. [40] [41] Large giant trevallies have been recorded as a host of the sharksucker, Echeneis naucrates, a fish which is normally seen attached to the undersides of sharks. [42]

Diet and feeding Edit

The giant trevally is a powerful predatory fish, from the estuaries it inhabits as a juvenile to the outer reefs and atolls it patrols as an adult. [22] [23] Hunting appears to occur at different times of the day in different areas of its range off South Africa it is most active during the day, especially at dawn and dusk, [20] while off Zanzibar and Hong Kong, it is nocturnal in its habits. [43] [44] The species' diets have been determined in several countries and habitats their diets generally vary slightly by locations and age. In all but one study (which was of juveniles), the giant trevally dominantly takes other fishes, with various crustaceans, cephalopods and occasionally molluscs making the remainder of the diet. [11] [45] In Hawaii, the species has a predominantly fish-based diet consisting of Scaridae and Labridae, with crustaceans, including lobsters, and cephalopods (squid and octopus) making up the remaining portion. The large number of reef fishes suggests it spends much of its time foraging over shallow-water reef habitats, but the presence of squid and the schooling carangid Decapterus macarellus indicates exploitation of more open-water habitats, as well. [22] Off Africa, the diet is similar, consisting mostly of fish including eels, with minor squid, octopus, mantis shrimp, lobsters and other crustaceans. [43] Younger fish inside Kaneohe Bay, Hawaii showed the only instance where crustaceans were preferred over fish stomatopods, shrimp and crabs were the most common prey taken at 89% of stomach content by volume, with fish, mostly of the family Blennidae, making up only 7% of the stomach contents. [27] Estuarine fish in both Hawaii and Australia have mostly fish-based diets, with crustaceans such as prawns and amphipods also of importance, and they are known to take more novel prey, such as spiders and insects, in these habitats. [23] [46] Juvenile turtles and dolphins were reported being found within the stomach contents of larger giant trevally. [47] Studies of different size classes of fish have found their diets change with age in some locations, with the changes relating to an increased volume of fish taken. [36]

Giant trevally also feed on fledgling sooty terns on Farquhar Atoll snatching them from the water surface and even jumping acrobatically to catch them in the air as seen on the BBC documentary Blue Planet II, episode 1. [48] So far this behaviour has not been observed elsewhere.

Studies in controlled environments on the giant trevally's feeding strategies have found hunting in schools increases their capture efficiency, but is not necessary for an individual's survival. When a school is formed during feeding, one individual will take a leading position, with others trailing behind it. Several individuals will attack the prey school, striking and stunning the prey, with the leading individual generally being more successful. Some individuals act individually and opportunistically within the school if one of the prey fish becomes isolated, with the main advantage of schooling appearing to be the ability to further break up and isolate prey schools. The only time hunting in schools is a disadvantage is when only isolated prey are present, such as close to a reef here, an individual hunter has a greater probability of capturing it than if a group is present. [49] Another hunting strategy of the giant trevally is to 'escort' monk seals, a behavior which has been observed near the Hawaiian Islands. The trevally swim close by the seal, and when the seal stops to forage, the trevally positions its mouth inches away from the seal. If a prey item is disturbed, the trevally will attempt to steal the prey from the seal, which routinely does occur. The seal does not appear to gain any benefit from this relationship, and it is thought juvenile seals being followed in this way may be outcompeted by the larger fish. [50] A similar strategy has been employed by fish in the presence of large reef sharks, as they use the larger animal as a tool to ambush prey. [47] The opportunistic nature of giant trevally has also been made evident by studies on the mortality rate of undersized or egg-bearing lobsters released from traps at the water's surface of the Hawaiian Islands. The fish are efficient predators of these crustaceans, with individuals often seizing a lobster before it could sink to the seafloor after being released, or attacking before the lobster moves into a defensive position. Some bolder, large individuals are even known to eat the lobster head first when it is in a defensive stance. [51]

Life history Edit

The giant trevally reaches sexual maturity at 54 to 61 cm in length and three to four years of age, [43] although many authors narrow this down to 60 cm and three years of age. [20] Sex ratio estimates from the Hawaiian Islands suggest the population is slightly skewed toward females, with the male:female ratio being 1:1.39. [22] Spawning occurs during the warmer months in most locations, although the exact dates differ by location. In southern Africa, this occurs between July and March, with a peak between November and March [43] in the Philippines between December and January, with a lesser peak during June [52] and in Hawaii between April and November, with a major peak during May to August. [22] Lunar cycles are also known to control the spawning events, with large schools forming in certain locations at specific phases of the moon in Hawaii and the Solomon Islands. [26] [38] Locations for spawning include reefs, the reef channels and offshore banks. [44] Sampling of schools prior to spawning suggests the fish segregate into schools of only one sex, although the details are still unclear. [43] Observations in the natural habitat found spawning occurred during the day immediately after and just before the change of tide when there were no currents. Giant trevally gathered in schools of over 100 individuals, although ripe individuals occurred slightly deeper around 2–3 m above the seabed in groups of three or four, with one silver female being chased by several black males. [52] Eventually, a pair would sink down to a sandy bottom, where eggs and sperm were released. The fish then diverged and swam away. Each individual appears to spawn more than once in each period, with only part of the gonads ripe in spawners. Fecundity is not known, although females are known to release several thousand eggs on capture during the spawning process. Eggs are described as pelagic and transparent in nature. [52]

The giant trevally's early larval stages and their behaviour have been extensively described, with all fins having formed by at least 8 mm in length, with larvae and subjuveniles being silver with six dark vertical bars. [25] Laboratory populations of fish show a significant variability in the length at a certain age, with the average range being around 6.5 mm. Growth rates in larvae between 8.0 and 16.5 mm are on average 0.36 mm per day. The speed at which larvae swim increases with age from 12 cm/s at 8 mm in length to 40 cm/s at 16.5 mm, with size rather than age a better predictor of this parameter. [25] Size is also a better predictor of endurance in larvae than age. These observations suggest the species becomes an effective swimmer (is able to swim against a current) around 7–14 mm. No obvious relationships with age and either swimming depth or trajectory have been found. Larvae appear to also opportunistically feed on small zooplankton while swimming. The larvae actively avoid other large fish, and jellyfish are occasionally used as temporary cover. Larvae have no association with reefs, and appear to prefer to live pelagically. [25] Daily growth is estimated at between 3.82 and 20.87 g/day, with larger fish growing at a more rapid rate. Length at the age of one year is 18 cm, at two years is 35 cm and by three years, the fish is around 50 to 60 cm. [22] The use of von Bertalanffy growth curves fitted to observed otolith data show an individual of around 1 m in length is about eight years old, while a 1.7 m fish would be around 24 years old. The maximum theoretical length of the species predicted by the growth curves is 1.84 m, [22] but the largest reported individual was 1.7 m long. As previously mentioned, as the giant trevally grows, it shifts from turbid inshore waters or estuaries to reefs and lagoons in bays, moving finally to outer reefs and atolls. [24] A hybrid of C. ignobilis and C. melampygus (bluefin trevally) has been recorded from Hawaii. The specimen was initially thought to be a bluefin trevally of world-record size, but was later rejected when it was discovered to be a hybrid. Initial evidence of hybridisation was morphological characteristics intermediate to the two species later genetic tests confirmed it was indeed a hybrid. The two species are known to school together, including at spawning time, which was considered to be the reason for hybridisation. [53]

The giant trevally has been used by humans since prehistoric times, with the oldest known records of the capture of this species by Hawaiians, whose culture held the fish in high regard. The ulua, as the fish is known to Hawaiians, was likened to a fine man and strong warrior, which was the cause of a ban on women eating the species in antiquity. [54] The species was often used in Hawaiian religious rites, and took place of a human sacrifice when none was available. Culturally, the fish was seen as a god, and treated as gamefish which commoners could not hunt. There are many mentions of ulua in Hawaiian proverbs, all generally relating to the strength and warrior-like qualities of the fish. [13] The Hawaiians considered the fish to be of excellent quality, with white, firm flesh. Despite this, intrusions of giant trevally into modern-day fishponds used by Hawaiians for rearing fish are unwelcome being a predator, it eats more than it is worth at market. [54]

The giant trevally is of high importance to modern fisheries throughout its range, although quantifying the amounts taken is very difficult due to the lack of fishery statistics kept in most of these countries. Hawaii has the best-kept statistics, where the 1998 catch consisted of 10,194 pounds of giant trevally worth around US$12,000. [13] Historically, the species has been taken in far greater numbers, and has been an important food, market and game fish since the early 1900s. However, their exploitation has seen the landings of the species decrease by over 84% since the turn of the century, declining from 725,000 lb to 10,000 lb in recent catches. [55] FAO statistics of the Asian region record catches between 4,000 and 10,000 tonnes between 1997 and 2007, [56] although this excludes most fisheries which are not monitored or do not discriminate between trevally species. The giant trevally is commercially caught by a number of methods, including hook and line, handlines, gill nets and other types of artisanal traps. The species has also successfully been bred for aquaculture purposes in Taiwan. [57] It is sold at market fresh, frozen, salted, and smoked, and as fishmeal and oil. [12]

The giant trevally is considered one of the top gamefish of the Indo-Pacific region, having outstanding strength, speed and endurance once hooked. [10] It can be taken by many methods, including baits of cut or live fish and squid, as well as a wide array of lures. The species is commonly taken on bibbed plugs, minnows, spoons, jigs and poppers, soft plastic lures and saltwater flies. [58] In recent years, the development of both jigging and surface-popping techniques has seen the giant trevally become an extremely popular candidate for catch and release fishing, [10] with many charter operators based around this concept. [47] The species is also popular with spearfishermen throughout its range. The species' edibility has been rated from poor to excellent by different authors, although numerous cases of ciguatera poisoning have been reported from the species. [59] Detailed tests on a large (1 m) specimen taken from Palmyra Island showed the toxicity of the fish's flesh, liver and washed intestinal tract produced no or weakly positive symptoms to laboratory mice, but the digested contents of the intestine were lethal. The authors argued, based on this test, the flesh of giant trevally was safe to consume. However, analysis of case studies in which ciguatera poisoning was reported after eating the fish suggested an accumulative effect occurs with repeated consumption and tests like the one outlined above are not reliable, as the toxin appears to be distributed haphazardly throughout each fish. [59] Since 1990, giant trevally taken from the main Hawaiian islands have been blocked from sale by auction internationally due to concerns over liability from ciguatera poisoning. [13]

Conservation Edit

A decline in giant trevally numbers around inhabited regions has been well documented in Hawaii, with both catch data as presented above and ecological studies showing this decrease in numbers. A biomass study in the Hawaiian Islands indicates the main Hawaiian Islands are heavily depleted in the species, which in untouched ecosystems comprises 71% of the apex predator biomass. In contrast, it comprises less than 0.03% of the apex biomass in exploited habitats, with only a single fish observed during the course of this research study. [39] Prior to this, a 1993 report suggested the population around the main Hawaiian islands were not stressed, though several biological indicators suggested to the contrary. This was due to the highly size-selective nature of the fishery, which theoretically should prevent a decrease in numbers. [60] Despite this, populations have decreased, and in light of their continued falling abundance in Hawaii, several recommendations, including banning the commercial take of the species, increasing minimum lengths and decreasing bag limits for anglers, as well as reassessment of protected areas for the species, have been proposed by officials. [13] The species (nor any other carangid) has not been assessed by the IUCN.

Some recreational fishing groups are also promoting a catch and release practice for the giant trevally, with this becoming an increasingly popular option for charter boat operators, who have also begun to tag giant trevally for scientific purposes. [61] At large sizes, the species is more likely to be ciguatoxic, so if the fish is kept, it must be disposed of or sent to a taxidermist if it is a trophy fish. A catch and release approach has also been adopted by operators outside Hawaii, with Australian operators who target the species by popping and jigging rarely keeping any fish. [10] Careful fish handling techniques have also been implemented by anglers so as not to damage the fish such techniques include supporting the fish's weight, using barbless single, rather than treble, hooks and restricting the time the fish spends out the water to a minimum. [47]


Nocturnal/Diurnal

White-tailed deer are crepuscular animals, meaning they are typically most active around dawn and dusk. This does not mean that deer are not at all active during the day. Deer activity may also be influenced by weather, seasonality, and human activity. During hot summer days, for example, deer are less active during the daytime and more active at night when it&rsquos cooler. Conversely, deer may be more active than usual during cooler weather. Deer activity may increase throughout the day during the breeding season while bucks are actively searching for does that are receptive to breeding. Areas with a lot of daytime human activity – which may include in the woods during the hunting season if hunter densities are high- may see little daytime deer activity and increased nocturnality of resident deer.


Gray Wolf (Canis lupus)

1) Why was the gray wolf listed as endangered?
Wolves became nearly extinct in the conterminous 48 states in the early part of the 20th century. Predator-control programs targeted wolves, and wolf habitat was altered and destroyed as eastern forests were logged and then converted to farms. Woodland caribou, bison, and beaver, the wolves’ prey base, were also brought to near-extinction by settlers and market hunters. Predator-control programs, loss of habitat, and loss of prey resulted in the elimination of wolves throughout most of the conterminous U.S. except in northeastern Minnesota and Isle Royale, Michigan. A few individuals also remained in the northern Rocky Mountains.

2) What types of habitat do wolves use?

Gray wolves use so many different habitat types that they are equally at home in the deserts of Israel, the deciduous forests of Wisconsin, and the frozen arctic of Siberia. Within North America, gray wolves formerly ranged from coast to coast with the exception of the mid-Atlantic states, the Southeast, and perhaps parts of California. They were found in almost all habitat types prairie, forest, mountains, and wetlands. In the conterminous 48 states today, they are found in mostly forested lands in Minnesota, Wisconsin, Michigan, Montana, Idaho, Oregon, Washington, and Wyoming. Although wolves in the western Great Lakes area primarily use northern woodlands, they have expanded their range into areas that are a mix of forest and agriculture in Minnesota and Wisconsin. The Mexican gray wolf has been reintroduced into the mountains of the Apache National Forest in Arizona and translocated into the Gila National Forest in New Mexico.

3) Do wolves need wilderness areas to survive? Can they survive near urban areas?

It was thought that gray wolves were a wilderness species, but wolf range has expanded into areas that we once thought could not support them. In Minnesota and Wisconsin, wolves have shown that they can tolerate more human disturbance than we previously thought. Consequently, it appears that wolves can survive anywhere there is sufficient food and human tolerance to allow their existence.

From a biological standpoint, we know that wolves can and do survive near urban areas. But whether wolves survive near cities and towns will depend on people. There are areas near large cities that have sufficient wild prey to support wolves. Wolves are predators, however, and conflicts arise when they kill livestock and domestic animals, including pets. These conflicts, along with urban hazards such as vehicle traffic, will likely limit the establishment of wolf populations near urban areas.

4) How far do wolves travel?

Wolf packs usually hunt within a specific territory. It is not uncommon for territories to be as large as 50 square miles but they may even extend up to 1,000 square miles in areas where prey is scarce. Wolves often cover large areas to hunt, traveling as far as 30 miles a day. Although they trot along at 5 m.p.h., wolves can attain speeds as high as 40 m.p.h. Most wolves disperse from the pack they were born into by age three. Dispersing wolves have traveled as far as 600 miles.

5) What do wolves eat?

In the Midwest, wolves eat mainly white-tailed deer but they also eat moose, beaver, and snowshoe hare. In the Rocky Mountains, wolves feed on elk, deer, moose, bison, and beaver. Wolves even eat some insects, small mammals, nuts, and berries. They may not eat for a week or more but are capable of eating 20 pounds of meat in a single meal.

6) If wolf numbers get too high, will deer and elk be eliminated?

Wolves have lived with their prey for many thousands of years, and the health of wolf populations is dependent on the health of their prey base. Under certain conditions wolves can cause local decreases in prey numbers. But if deer and elk numbers were to decline over an extended period of time, due to severe winter conditions or habitat changes, wolves would have less food available and their health would decline. They would then produce fewer pups and fewer pups would survive to adulthood. Also, more adult wolves would die because of poor health or in conflicts with other wolves. Thus, wolf numbers would decline before their prey could be eliminated.

Isle Royale, Michigan, serves as a living laboratory to illustrate this point. One female gray wolf naturally emigrated to this island (about 132,000 acres) more than 50 years ago and eventually three packs were established. Their primary prey is moose. Through the years the numbers of moose and wolves have fluctuated, but after 50 years a moose population continues to survive on Isle Royale.

7) Do wolves really take the old, young, sick, starving, or injured animals?

It is well-documented that wolves tend to do this. Hunting and bringing down big game is dangerous work and wolves are sometimes killed by elk, moose, and even deer. In the wild, they cannot afford to be injured therefore, they go after the safest animals to kill and often leave strong animals alone. A recent study of wolf predation on elk in Yellowstone National Park, for example, found that wolves tend to kill calves and older animals – adult elk killed by wolves were about 7 years older than elk killed by hunters. If weather or other conditions make prey unusually vulnerable, wolves can and do kill prime-aged animals but wolf predation tends to be selective.

8) How do wolves in an area affect deer hunting?

Wolves survive by preying primarily on the most vulnerable individuals in the deer population (the very young, old, sick, injured, or nutritionally compromised) thus under certain conditions their impacts on the deer population are most likely compensatory rather than additive. That is, many of the deer that wolves kill likely would have died from other causes such as starvation or disease.

However, when weather events occur, such as deep snowfalls or drought, wolves can be a factor that reduces deer numbers further. For example, since wolves became protected in northern Minnesota in 1978, there has been a high and even increasing harvest of deer by hunters. But two consecutive hard winters (1995-96 and 1996-97) reduced the size of the state’s northern deer herd, which in turn resulted in much lower deer harvests. Wolves likely were accountable for a portion of the lower deer numbers and, in turn, the lower deer harvest. Subsequent mild winters resulted in a rebounding of the deer herd, despite the increasing wolf population. The years 2005 through 2007 produced the highest deer harvests ever, with Minnesota deer hunters harvesting over 250,000 white-tailed deer during each of those hunting seasons – an approximate five-fold increase in hunter deer harvest since wolves were listed under the ESA in 1978.

Locally, the presence of wolves can reduce hunter success. The presence of wolves changes deer movements and behavior. Also some wolves hunt around bait piles that attract and concentrate deer, which may reduce the chances that deer will frequent the bait sites.

9) Do wolves kill more than they can eat?

Sometimes, but rarely. The few times that wolves have been documented killing more than they could eat were when conditions such as deep snow or other unusual circumstances made it easy for them to kill their prey. Even then, they returned to those kills and continued to use them.

10) Does the presence of wolves affect the numbers of animals other than their prey?

As one of the top predators in the food chain, wolves have a definite impact on their ecosystem. Studies at Yellowstone are finding that the effect of wolves cascades throughout the Park’s ecosystems. Ravens, foxes, wolverines, coyotes, bald eagles, and even bears benefit because they feed on carcasses of animals killed by wolves. Coyotes declined because wolves view them as competition and keep them out of their territories which may be responsible, in part, for an increase in small rodents. Elk changed their behavior to avoid wolf predation, which allowed willow, aspen, and cottonwood regrowth. This, in turn, provided food for beavers and habitat for songbirds. The ecosystem changes and cascading effects continue and are expected to do so for some time.

11) What is a wolf pack?

The wolf pack is an extended family unit that includes a dominant male and female, referred to as the alpha pair. In each pack, the alpha animals are usually the only ones to breed, preventing subordinate adults from mating by physically harassing them. Thus, most packs produce only one litter of four to six pups each year. A pack typically includes the alpha pair, the young wolves born that year, perhaps last year’s young, and sometimes a few older wolves that may or may not be related to the alpha pair.

12) How many wolves are in a pack?

Pack sizes vary considerably, depending on the size of the wolf population in a particular area, whether they are feeding pups and the amount of prey available. Average pack size in the Midwest varies from 4 to 8 wolves during winter with records of up to 16. In the northern Rocky Mountains, packs average about 10 wolves, but one pack in Yellowstone had 37 members. That pack then formed several smaller packs. Pack size can temporarily be as high as 30 or more in parts of Canada and Alaska but most packs are much smaller.

13) Do wolves mate for life?

Usually, a wolf pair may mate until one dies and then the living mate will find another mate.

14) What happens to a pack when the alpha male or female is killed?

In a Yellowstone wolf study, which is a study of a population that is not hunted or trapped, the death of one or both members of the alpha pair usually resulted in another adult wolf coming in to replace the one that died. Sometimes it led to dissolution of the pack. Packs sometimes adopt unrelated dispersing wolves that could also become alpha members of the pack. When packs dissolved after the death of an alpha animal, new packs formed in those areas.

15) How does a non-breeding wolf attain breeding status?

A wolf can stay with the pack into which it was born and bide its time until it works its way up the dominance hierarchy or it can disperse. A dispersing wolf leaves the pack to find a mate and a vacant area in which to start its own pack. Both strategies involve risk. A wolf that bides its time may be out-competed by another wolf and never achieve dominance. Dispersers must hunt on their own until they form or join a new pack, and they may be killed when they invade the territory of other wolves.

Dispersers can leave a pack at any time of year but usually leave the pack in autumn or winter, during hunting and trapping season and prior to the February breeding season. They must be alert to entering other wolf packs' territories and they must keep a constant vigil to avoid encounters with people, their major enemy. Dispersers have been known to travel great distances in a short time. One radio-collared Wisconsin wolf traveled 23 miles in one day. In ten months, one Minnesota wolf traveled 550 miles to Saskatchewan, Canada. In 2001, a wolf trapped in the western portion of Michigan’s Upper Peninsula was killed in north-central Missouri, about 600 miles from its home territory, by a farmer who stated that he thought it was a coyote.

16) When do wolves mate?

The breeding season for wolves is from late January through March the further south, the earlier the breeding season. Females are pregnant for about 63 days before they give birth to four to six pups.

17) Where do wolves give birth to their young?

Pups are usually born in a den excavated as much as 10 feet into well-drained soil. Sometimes the female selects a hollow log, cave, tree with overhanging branches, or abandoned beaver lodge instead of making a den. At birth, wolf pups are deaf and blind, have dark fuzzy fur and weigh about one pound. They begin to see when two weeks old and can hear after three weeks. At this time, they become very active and playful.

18) At what age are wolf pups weaned?

Wolf pups are weaned at about six weeks old, and then the adults begin to bring them meat. Most adult wolves center their activities on dens while traveling as far as 20 miles away in search of food, which is regularly brought back to the den. Adults eat the meat at a kill site, often miles away from the pups, and then they return and regurgitate the food for the pups to eat. The hungry pups jump and nip at the adults' muzzles to stimulate regurgitation.

19) How long do wolf pups stay in the den?

By mid- to late summer, when the pups are six to eight weeks old, they are usually moved some distance away from the den. The female carries the pups in her mouth to the first of a series of rendezvous sites or nursery areas. These sites are the focus of the pack's social activities for the summer months and are usually near water. By August, the pups wander up to two to three miles from the rendezvous sites and use them less often. The pack abandons the sites in September or October, and the pups, now almost full-grown, follow the adults.

20) How long do wolves live?

Gray wolves are known to live up to 13 years in the wild and 15 years in captivity.

21) In protected populations, what kills wolves?

In natural situations pups die from starvation and adults die from being killed by members of neighboring packs. Adults can also starve to death if the prey base is not adequate. Diseases, such as canine parvovirus and mange, also kill wolves, especially pups. Sometimes adult wolves are killed by animals on which they intended to prey.

22) Are wolves a threat to humans, in particular small children?

Aggressive behavior from wild wolves towards humans is rare. Mark McNay of the Alaska Department of Fish and Game compiled information about documented wolf-human encounters in “A Case History of Wolf-Human Encounters in Alaska and Canada” which was published in 2002. There are 59,000 to 70,000 gray wolves in Alaska and Canada, and since 1970 there were 16 cases of non-rabid wolves biting people. Six of those cases were severe. Since that report was written, wolves killed a man in Saskatchewan, Canada in 2005. It appears to have been a situation where wolves were feeding in an unregulated garbage dump and became habituated to people. In 2010 a woman jogging outside a remote village in Alaska was killed by wolves.

Wild wolves generally are shy of people and avoid contact with them whenever possible. However, any wild animal can be dangerous if it is cornered, injured or sick, or has become habituated to people through activities such as artificial feeding. People should avoid actions that encourage wolves to spend time near people or become dependent on them for food.

Where the wolf remains listed as endangered, the Endangered Species Act allows take of any endangered or threatened species if there is an immediate threat to human safety. If someone is in a situation where they feel they or someone else is in immediate danger from a wolf, they can kill the wolf. Additionally, state and federal land management agencies can remove or kill a wolf that presents a demonstrable, non-immediate threat to human safety. In areas where the wolf is no longer protected by the Endangered Species Act, state regulations define the actions that people can take to protect themselves if they feel threatened by a wolf.

23) Is there any danger from wolves to my pets?

Yes, in some situations. Attacks on dogs in residential areas are uncommon but have been on the increase as wolf numbers and range are increasing. The Wisconsin DNR has guidance on their website for dog owners who live in wolf country: http://dnr.wi.gov/org/land/er/mammals/wolf/guidance.htm. When walking dogs in wolf country, to protect both pets and wildlife, pets should always be carefully monitored by their owners. Unsupervised dogs that stray from their owner’s homes or from their handlers into wolf territories are definitely at risk. Wolves will treat dogs as interlopers on their territories and may attack and kill them, especially if the wolves have pups nearby.

The majority of documented pet dogs killed by wolves have been hounds used for hunting bear in Wisconsin and Michigan and used for hunting bear and mountain lion in the northern Rocky Mountains. Hunting dogs are killed by wolves while the dogs are trailing game for training purposes during off-season times and while hunting during regulated seasons. The Wisconsin DNR has “A Guide for Reducing Conflict Between Wolves and Hunting Dogs” on their website at http://dnr.wi.gov/org/land/er/mammals/wolf/wolfhuntdog.htm.

24) Do wolves make good pets?

No, wolves or wolf-dog hybrids do not make good pets. The idea of owning a wolf or a wolf-dog cross is appealing to many people, but the reality of owning one of these animals is often very different. While wolf puppies might be as cute as dog puppies, they will grow up to be wolves, not dogs, no matter how much they are treated like dogs. With wolf-dog crosses, or hybrids, the higher the percentage of wolf genes, the more wolf-like behavior the hybrid will exhibit. There is no way of knowing the percentage of wolf genes in a cross that is an offspring of a hybrid.

Many an unsuspecting wolf lover has purchased a wolf pup, only to find that it is largely untrainable, because it does not care much about pleasing its owner. As it grows into adulthood it becomes unpredictable, if not downright dangerous, especially around children and small animals. Such animals often live miserable lives on the end of a chain after a frustrated owner gives up on attempting to train the animal. Wolf or hybrid owners who are unable to cope with their "pet" may elect to either pass the animal along to another unsuspecting wolf lover or sentence the animal to life at a sanctuary (many such facilities exist, but most are already overcrowded). Some may release the animal to the wild, where it will most likely starve to death or because of its familiarity with people, be involved in depredation incidents resulting in wild wolves being unfairly blamed. Releasing wolf-dog hybrids is prohibited in some states.

25) How big are wolves?

The size of a wolf varies depending on where it is found. Smaller sizes tend to be found in the southern portion of wolf range and larger sizes in the northern portion. Females tend to be slightly smaller than males. The average size of males is 5 to 6.5 feet long (tip of nose to tip of tail), 26 to 32 inches high at the shoulder, and 70 to 115 pounds in weight (in Alaska they occasionally reach 145 pounds). The average size of females is 4.5 to 6 feet long, 26 to 32 inches high at the shoulder, and 60 to 100 pounds in weight. Wolves reach adult size by 1 year of age.

26) How can you tell the difference between a gray wolf and a coyote or a large dog?

Size is a key difference between coyotes and wolves. Coyotes range from 3.5 to 4.5 feet long, 16 to 20 inches high at the shoulder and 20 to 50 pounds. This is about half the size of a wolf. Coyotes tend to have gray or reddish brown fur with rusty colored legs, feet, and ears, and whitish fur on the throat and belly. Their ears are pointed and relatively long, and the muzzle is pointed and petite. The track size is about 2.5 inches long and 1.5 inches wide. Coyotes tend to carry their tail held below the back line. The tail may or may not be black tipped and is less than 18 inches long. In contrast, wolves have many color variations but tend to be buff-colored tans grizzled with gray and black (although they can also be black or white). Their ears are rounded and relatively short, and the muzzle is large and blocky. Wolves generally hold their tail straight out from the body or down. The tail is black tipped and over 18 inches long. A wolf track size is about 4.5 inches long and 3.5 inches wide.

Wolves and other wild canids usually place their hind foot in the track left by the front foot, whereas a dog's front and hind foot tracks usually do not overlap each other. Only a few breeds of dogs leave tracks longer than 4 inches (Great Danes, St. Bernards, and some bloodhounds). Although the tails of many dogs are curled coyote and wolf tails are never seen curled.

27) How can I learn more about wolves and the things that are going on right now that will affect their future?

Information about wolves in the western Great Lakes states is on the Service’s Website at http://www.fws.gov/midwest/wolf, information about wolves in the northern Rocky Mountains is on the Service’s Website at http://www.fws.gov/mountain-prairie/species/mammals/wolf/ and information about wolves in the Southwest (Mexican gray wolf) is on the Service’s Website at http://www.fws.gov/southwest/es/mexicanwolf/. Mailing addresses for information about gray wolves are:

For the western Great Lakes :

U.S. Fish and Wildlife Service
5600 American Blvd. West, Suite 990
Bloomington, MN 55437

For the northern Rocky Mountains:

U.S. Fish and Wildlife Service
Western Gray Wolf Recovery Coordinator
100 N. Park, #320
Helena,Montana 59601

U.S. Fish and Wildlife Service
Mexican Wolf Recovery Coordinator
2105 Osuna Road NE
Albuquerque, NM 87113

Revised December 2011

USFWS Ecological Services Field Offices in the Upper Midwest


Introduction

A minor proportion of all species on Earth are known [1]. At the same time, anthropogenic impacts have initiated a mass extinction of species in the “Anthropocene” [2], with pervasive and often negative consequences for ecosystem functioning and human well-being [3,4]. To counteract biodiversity loss, fast and reliable tools are needed to assess and monitor biodiversity [5].

Stream biodiversity is particularity affected by anthropogenic degradation [6,7]. Therefore, large-scale monitoring and management programs have been established, for example, the European Union Water Framework Directive and the US Clean Water Act. In these biomonitoring programs, species lists, particularly of benthic invertebrate indicator species, are the central metric to assess the ecological status of freshwater ecosystems. For stream assessments, hundreds of benthic organisms are sampled in a standardised fashion, sorted, identified, and used in standardised analytical work flows (e.g. [8,9]). However, many benthic invertebrate larvae are difficult to identify at the species level, and thus the most practical taxonomic level for the identification of these organisms is often only the genus or family [10]. This is a major concern, as different species within a genus or subfamily can have different ecological preferences and stress tolerances and belong to different functional feeding groups [11,12] see [13] for review. Even worse, frequent identification errors occur and many specimens are not detected in samples [10] these limitations have direct consequences for the inferred ecosystem assessment metrics [10,14] and thus management decisions.

DNA barcoding allows for standardized and accurate species identification [15–18]. As this method is DNA based, it can be used to identify species reliably even when juvenile instars or fragments of organisms are available. For animals, a 658-bp standardized fragment of the mitochondrial gene COI (cytochrome c oxidase subunit 1) is typically used [19]. DNA barcoding requires the establishment of an accurate reference database. For macroinvertebrates, this is best achieved by determining diagnostic characters (usually in male adult specimens [13,20,21]), sequencing the specimens, and depositing the COI sequences in a database such as the BOLD database [22]. In times of declining taxonomic expertise [23,24], these curated and public barcode databases are indispensible to conserve taxonomic knowledge.

COI barcoding methods are well established for freshwater organisms [16,17,25] and initial studies have tested their potential for freshwater ecosystem assessments using classical Sanger-based sequencing [14,26]. Stein and co-authors showed that ten of 16 assessment metrics had higher statistical power using DNA barcoding than morphological assessment [14]. However, Sanger sequencing requires that each specimen is processed individually in the laboratory, which is costly and extremely time-consuming for routine community assessments involving hundreds or thousands of specimens per sample.

This challenge can be overcome with the aid of next-generation sequencing, which enables the simultaneous analysis of millions of sequences. One next-generation sequencing technique termed metabarcoding (also called community barcoding) utilises the same principle as classical barcoding, yet with much higher throughput, allowing the simultaneous processing of hundreds of samples in a single analysis. When complete specimens are identified in bulk, it was suggested to use the term DNA metabarcoding to make a distinction to approaches using environmental DNA (eDNA) [27]. However, as our findings largely apply to eDNA-based methods as well, we here refer to metabarcoding in a broad sense. Metabarcoding is currently being tested to address a wide range of biological problems, such as invasive species detection [28], gut content analysis [29], and assessment of microbial [30] and metazoan diversity, such as that of arthropods (e.g. [31,32]). Initial studies on benthic diatoms [33] and macroinvertebrates [34] show the potential of this method to revolutionise the way we monitor stream ecosystems. However, there are general challenges associated with the use of metabarcoding for ecosystem assessments. While preliminary bioinformatic pipelines for data analysis are available (e.g., Mothur [35], QIIME [36], UPARSE pipeline [37]), barcode reference databases are still incomplete. There are furthermore two problems of central importance that have not been addressed systematically. First, sampled organisms have vastly different biomasses, and thus small organisms may be lost owing to low number of sequence reads [38]. Second, the amplification efficiency of the COI gene varies among species, and this might severely bias results [34,39] particularly in view of the variation in biomass. Precise estimates of biomass with respect to specimen recovery and primer bias have not been performed.

We describe an innovative and efficient strategy to analyse macroinvertebrate samples on an Illumina MiSeq sequencing platform. High sequence similarity in in amplicon sequencing can lead to decreased sequence quality on Illumina platforms [40]. We deal with this issue by using uniquely tagged fusion primers targeting the standard barcoding region, which are simultaneously sequenced in forward and reverse sequencing direction to increase nucleotide diversity and thus improve read quality. With the new protocol, we performed two controlled experiments to address the two problems outlined above. First, we assessed the relationship between biomass and sequence abundance by sequencing genetically distinct specimens that differ widely in biomass, but belong to a single species. This allowed us to determine whether and when small specimens are lost owing to low read coverage. Second, we used equal amounts of tissue from 52 freshwater taxa to determine how well they are recovered given species-specific PCR amplification bias when extracting many species in bulk. All analyses were performed with ten replicates to improve statistical robustness.


21 Animals in danger of extinction – List

Polar Bear

Polar bears live most of their life in solitary. They are active for most of the year, always in search for a meal. They are extremely strong, using their bowed legs to cover ground quickly. Their padded feet are full of hair, which gives them more control on slippery ice.

Polar bears are expert swimmers. They use their muscular front legs to propel them through the icy water. They are able to stay submerged for up to 2 minutes, while searching for food. The longest known dive lasted for 3 minutes and 10 seconds.

  • Size: Males 2.4–3 m (7 ft 10 in–9 ft 10 in) & Females 1.8–2.4 m (5 ft 11 in–7 ft 10 in)
  • Weight: Males 350–700 kg (772–1,543 lb) & Female 150–250 kg (331–551 lb)
  • Diet: Seals, fish and vegetation.
  • Geographical location: Greenland, Norway, Russia, Canada & United States (Alaska)
  • Cause of extinction: Habitat loss due to climate change

Tiger

Like the polar bear, tigers are solitary animals. They are nocturnal, hunting large animals. They make a kill about twice a week but are forced to do so more regularly if only small animals are available. Sometimes they cover an area of over 32km (20 miles) in one night in search of food.

Tigers are shy animals and make every effort to avoid humans. However, they have been known to attack domestic cattle when food resources are exceptionally low. Female tigers (tigresses) only give birth once every two years. Cubs will rely on their mothers until they are two years old.

  • Size: Males 250 to 390 cm (8.2 to 12.8 ft) | Females 200 to 275 cm (6.56 to 9.02 ft)
  • Weight: Males 90 and 306 kg (198 and 675 lb) | Females 65 to 167 kg (143 to 368 lb)
  • Diet: Sambar deer, Manchurian wapiti, barasingha and wild boar.
  • Geographical location: Wild tigers live in Asia. Larger subspecies, such as the Siberian tiger, live in eastern Russia and northeastern China. Smaller subspecies live in India, Bangladesh, Nepal, Bhutan, Myanmar, Laos, Cambodia, Vietnam, Malaysia and Indonesia.
  • Cause of extinction: Habitat loss due to climate change and illegal tiger trade.

Orangutan

How many left: Bornean 104 700 & Sumatran 7500

Orangutans are diurnal. That means they are mostly active during the day, just like humans.

While Bornean orangutans may climb to the ground from time to time, Sumatran orangutans hardly ever venture down, spending the majority of their lives up in the forest canopy.

It’s because of their tree top lifestyle that orangutans have developed stronger and longer limbs than any of the other ape species.

  • Size: Females 115 cm (3 ft 9 in) tall | Males 137 cm (4 ft 6 in).
  • Weight: Females 37 kg (82 lb) | Males 75 kg (165 lb).
  • Diet: Bark, leaves, flowers, a variety of insects, and most importantly, over 300 kinds of fruit.
  • Geographical location: Borneo and Sumatra.
  • Cause of extinction: Destruction of habitat and illegal animal trade.

Blue Whale

How many left: 5000 to 15 000

The blue whale is the largest animal to have ever existed on planet earth. Its tongue alone weighs more than an elephant and its heart is the size of a car.

Blue whales are found in all the world’s oceans, except for the Arctic. They usually swim alone or in groups of two to four. However, if food supply is in great quantities, as many as 60 blue whales may come together.

They use incredibly loud vocal sounds in order to communicate with one another. Their sounds are the loudest of any animal on the planet, and can be heard for hundreds of kilometers.

  • Size: 72.1 ft (22.1 m) to 102 ft (31.1 m)
  • Weight: Males 100 tons (200,000 lb) | Females 112 tons (224,000 lb) (Northern hemisphere)
  • Diet: Krill
  • Geographical location: Can be found in all oceans, except the Arctic. (View full list of countries).
  • Cause of extinction: The effect climate change has on their food source. Still recovering from the impacts of 20th Century whaling.

Socorro Isopod

How many left: Less than 2500

This is one of the more unusual animals in danger of extinction. The Socorro Isopod is a tiny aquatic crustacean. Females produce broods every two months with April being the peak reproductive period. Brood sizes range from three to 57 eggs.

  • Diet: Algae
  • Geographical location: New Mexico
  • Cause of extinction: Restricted habitat.

Amur Leopard

When you think of leopards, you probably think of the vast open savannas in Africa. But in the Russian far east, a rare subspecies has adapted to life in the temperate forests.

Amur leopards can run up to speeds as fast as 60km/h (37 mph). What’s more impressive is their ability to jump more than 6m (19 feet) horizontally and up to 3m (10 feet) vertically.

Once the leopard has made a kill, it carries and hides its victim so that it is not stolen by other predators. Interestingly, some males have been reported to stay with females after mating and even help with rearing the young.

The Amur leopard is also known as the Far East leopard, Manchurian leopard, and Korean leopard. In each of these locations, the species is in extreme danger of extinction.

  • Size: Males 107–136 cm (42–54 in) | Females
  • Weight: Males 32.2–48 kg (71–106 lb) | Females 25–42.5 kg (55–94 lb)
  • Diet: Deer, young wild boar, spotted deer and red deer calves.
  • Geographical location: Russia, China and North Korea
  • Cause of extinction: Habitat loss due to deforestation and poaching

African Wild Dog

The African wild dog is currently the second most endangered canid in Africa after the Ethiopian wolf. It is furthermore the most endangered carnivore in South Africa. Its behavior is rather unique amongst canid species. African wild dogs form incredibly strong social bonds with one another and are super intelligent.

Wild dogs are some of the most successful hunters in the world and the most successful predatory mammals in Africa. They have a staggering 80% success rate. In comparison, the lion has a measly 30% success rate.

  • Weight: Males 32.7 kg (72 lb) | Females 24.5 kg (54 lb)
  • Diet: Greater kudu, Thomson’s gazelle, impala, bushbuck and blue wildebeest.
  • Geographical location: Botswana, Zimbabwe, Namibia, Zambia, Tanzania, and Mozambique.
  • Cause of extinction: Habitat fragmentation, conflict with human activities and infectious disease.

Eastern Lowland Gorilla

The eastern lowland gorilla, also known as the Grauer’s Gorilla, is the largest of the four gorilla subspecies. These gorillas follow a completely vegan diet and are solid muscle.

They make their home in the lowland tropical rainforests of eastern DRC (Democratic Republic of Congo), a country plagued by many years of unrest. Within 50 years, the gorilla’s range has decreased by a staggering 9100 km2 (3500 square miles).

In the mid-1990s there were nearly 17 000 eastern lowland gorillas. Today, their numbers have dropped by 50%. Many years of violence in the region has made it impossible for an accurate accounting of the animals.

Gorillas are considered highly intelligent. Some individuals in captivity, such as Koko, have been taught a subset of sign language. Like the other great apes, gorillas can grieve, laugh have “fulfilling emotional lives”, develop strong family bonds, make and use tools, and think about the past and future.

  • Size: Males 1.85 metres (6.1 ft) | Females 1.6 metres (5.2 ft)
  • Weight: Males 210 kilograms (460 lb) | Females 100 kilograms (220 lb)
  • Diet: They eat every part of the plant, including roots, leaves, fruit, stems, flowers, bark, and even fungi (e.g. mushrooms)
  • Geographical location: Democratic Republic of Congo
  • Cause of extinction: Habitat loss caused by deforestation and poaching.

The Giant Panda

Today, giant pandas are considered a national treasure in China. They make the temperate forests high in the mountains of southwest China their home. For food pandas subsist almost entirely on bamboo. Bamboo has low nutritional value. Thus, they need to eat around 12 to 38 kg (26 to 84 lbs) of it every day.

Despite their bulk, these bears are exceptional at climbing trees. When a newborn panda is born, they are about the size of a lunchbox, about 1/900 th the size of their mothers.

  • Size: 1.2 to 1.9 metres (3 feet 11 inches to 6 feet 3 inches).
  • Weight: Males 160 kg (350 lb) | Females 70 kg (150 lb).
  • Diet: Bamboo.
  • Geographical location: China.
  • Cause of extinction: Loss of habitat and poaching.

Black Rhinoceros

The most notable difference between the black and white rhino is their upper lip. The black rhino has a hooked upper lip where white rhinos have square upper lips. This hooked upper lip allows it to eat casually from bushes and trees, whereas the white rhino grazes the ground for food.

Between 1960 and 1995, the black rhino population dropped by a staggering 98%. Their numbers measured only 2500. Since then, the species has made an amazing comeback from the brink of extinction.

Despite the comeback, black rhinos are still considered critically endangered and in danger of extinction. Wildlife crime, in this case the illegal trade of rhino horn, continues to plague the species and threaten their recovery.

  • Size: 3–3.75 m (9.8–12.3 ft) in length.
  • Weight: 800 to 1,400 kg (1,760 to 3,090 lb) – Unusually large male specimens have been reported at up to 2,896 kg (6,385 lb).
  • Diet: Leafy plants, branches, shoots, thorny wood bushes, and fruit.
  • Geographical location: South Africa, Namibia, Zimbabwe and Kenya.
  • Cause of extinction: Illegal wildlife trade – Demand for rhino horn, particularly from Vietnam and China.

Saola

How many left: Less than 750 (Rough estimation by IUCN)

The saola, also known as the Asian unicorn, was only discovered in May 1992 in the forests of north-central Vietnam. The find turned out to be the first large mammal new to science in more than 50 years.

A saola’s two parallel horns can reach a mighty 20 inches in length. The horns are found on both male and female.

These antelope-like animals have snow white markings on the face and large maxillary glands on their muzzle, which is thought to be used to mark their territory or to attract mates.

The saola are found solely in the Annamite Mountains of Vietnam and Laos.

  • Weight: 176-220 lbs
  • Diet: Leafy plants.
  • Geographical location: Vietnam and Laos.
  • Cause of extinction: Hunting (their horns are prized possessions) and habitat loss.

Hawksbill Turtle

How many left: Fewer than 25 000 nesting females remain.

The hawksbill turtle has a long narrow beak, hence the name. They have a beautifully distinct pattern of overlapping scales on their shells. It’s these colored shells that make them a target for illegal hunting. They are valuable and commonly sold as “tortoiseshells” in markets.

The hawksbill turtle is mainly found in the world’s more tropical oceans, mostly in coral reefs.

Interestingly, these sea turtles are living representatives of a group of reptiles that existed on our planet many millions of years ago. They are the primary link in marine ecosystems, ensuring the overall health of coral reefs.

Furthermore, sea turtles are a keystone species, which means they are an important part of their environment and influence other species around them.

  • Size: 76cm – 88cm (30-35 inches)
  • Weight: 40kg – 60kg (90-150 pounds)
  • Diet: Primarily sea-sponges. They also feed on algae, jellyfish and anemones.
  • Geographical location: Atlantic, Pacific, and Indian Oceans.
  • Cause of extinction: The harvesting of hawksbill turtles for their shell and plastic pollution.

Whale Shark

How many left: A population of 7011 was reported in 2016

Whale sharks, known as marokintana (many stars) in Madagascar, are indeed both the largest shark and fish alive today. Whale sharks cover huge distances, always in search of food. This is the only way they can sustain their massive weight.

The majestic creatures are found in all the tropical oceans of the world. Even so, scientists have yet to observe females giving birth to their young. This practice remains a mystery til this day.

Mature whale sharks can often be found feeding at the ocean surface, but have been known to dive to depths of up to 1000 m (3300 feet) in search of food.

  • Size: 9.8 m (32 ft) (Average size) – 18 m (59 ft) (Exceptionally large).
  • Weight: 9 t (20,000 lb).
  • Diet: Plankton.
  • Geographical location: Indian, Pacific and Atlantic oceans.
  • Cause of extinction: Commercial fisheries threaten this species.

Yangtze Finless Porpoise

How many left: 1000 to 1800

The Yangtze finless porpoise is characterized by its mischievous smile and has the same level of intelligence as that of a gorilla.

The longest river in Asia, the Yangtze River, was once home to both the Yangtze finless porpoise and the Baiji dolphin. However, in 2006 the Baiji dolphin was declared functionally extinct. This was the first time in history that an entire dolphin species was wiped off the face of the planet due to human activity. Now, the Yangtze finless porpoise faces a similar fate.

  • Size: 2.27 m (7 ft 5 in)
  • Weight: 72 kg (159 lb)
  • Diet: Fish, crustaceans, shrimp, squid, octopus and cephalopods.
  • Geographical location: Japan, China, Korea, Indonesia, Malaysia, India, and Bangladesh.
  • Cause of extinction: Overfishing, pollution and ship movement.

Borneo Pygmy Elephant

How many are left: Approximately 1500

The pygmy elephants of Borneo are the smallest elephants in the whole of Asia and in danger of extinction. These elephants are characterized by their oversized ears, plump bellies, and overly long tail, which sometimes even drags on the ground as they walk.

The Borneo pygmy elephant is also more “chilled out” than their Asian elephant counter parts, which are known to be quite aggressive at times.

The fable goes that these elephants were the remnants of a domesticated herd once given to the Sultan of Sulu in the 17 th century. However, it was determined by the WWF that they are in fact genetically different from other Asian elephants. DNA has proved that these majestic creatures were isolated from their cousins around 300 000 years ago. As time passed, they became smaller and smaller, whilst their ears continued to grow along with their tails.

  • Size: 2.4m (8.2 ft) to 2.9m (9.8 ft) tall
  • Weight: 2948 kg – 4989 kg (6,500-11,000 pounds)
  • Diet: Roots, grasses, leaves, bananas and sugarcane.
  • Geographical location: Indonesia and Malaysia.
  • Cause of extinction: Deforestation and habitat loss due to the palm oil industry.

Atlantic Bluefin Tuna

How many are left: Unknown

Bluefin tuna are the largest species of tuna and can live up to 40 years. These animals are migrants, swimming across all oceans and can dive deeper than 1000 m (3300 ft). Their anatomy is built for speed, shaped like torpedoes they can reach speeds of 60 km/h (620 mp/h) or more.

From the moment they hatch, they use their incredible sight (the best of all bony fish) to hunt schools of fish like mackerel.

In all, there are 3 species of bluefin: Atlantic (the largest and most at risk of extinction), Pacific, and Southern. The majority of bluefin are caught in the Mediterranean sea, the most pivotal location worldwide for the bluefin fishing industry.

A report by the International Scientific Committee for Tuna and Tuna-like Species, shows the present population of bluefin tuna has dropped by 94% due to overfishing.

  • Size: 2–2.5 m (6.6–8.2 ft) long.
  • Weight: 225–250 kg (496–551 lb).
  • Diet: Small fish, squid and crustaceans.
  • Geographical location: Western and eastern Atlantic Ocean, as well as the Mediterranean Sea. (These animals have become extinct in the Black Sea.)
  • Cause of extinction: Overfishing, driven by the demand for this fish in high-end sushi markets.

Chimpanzee

How many are left: 172,700 to 299,700

Chimpanzees are extremely intelligent, social animals, who care for their young for many years. These apes are in fact our closest cousins. We share around 98% of our genes.

Chimps spend most of their days in the treetops of central Africa. When they do decide to come down to earth, they usually move on all fours, but have been known to walk upright for over a mile (1,6 km).

Chimpanzees are also known to use tools, such as fishing for termites with a stick and using bunched up leaves to collect rainwater.

Despite being our closest connection to the animal kingdom, humans are putting these animals in danger of extinction. Chimps have already disappeared from as many as four countries and are under tremendous pressure where they do remain.

  • Size: 100–150 cm (3 ft 3 in–4 ft 11 in) tall.
  • Weight: Males 40–70 kg (88–154 lb) | Females 27–50 kg (60–110 lb).
  • Diet: Prefers fruit above all other food items but also eats leaves and leaf buds, seeds, blossoms, stems, pith, bark, resin, honey, soil, insects, birds and their eggs, and small to medium-sized mammals, including other primates.
  • Geographical location: Central and western Africa.
  • Cause of extinction: Habitat destruction, hunting, and disease.

Giraffe

Have you ever wondered who the tallest mammal is? Well, incase you never guessed it, it’s the giraffe. This is thanks to their incredibly long neck and legs. The legs alone are taller than most humans. They allow giraffes to sprint as fast as 56km/h (35 mph) or cruise comfortably at 16km/h (10 mph).

These fascinating animals are usually spotted in groups, roaming the vast open grasslands in search of the freshest twigs and shrubbery.

Today, giraffes are in serious danger of extinction. The overall population has declined by 40 percent within the last 30 years. The herds that remain face many threats ranging from habitat loss to poaching.

  • Size: 4.3–5.7 m (14.1–18.7 ft) tall.
  • Weight: Males 1,192 kg (2,628 lb) | Females 828 kg (1,825 lb).
  • Diet: Twigs of trees, preferring trees of the subfamily Acacieae and the genera Commiphora and Terminalia. They also eat shrubs, grass and fruit.
  • Geographical location: Kenya, Cameroon, Chad, Niger, Uganda, Namibia, Botswana, Zimbabwe, Zambia, Tanzania, Angola, and South Africa.
  • Cause of extinction: Habitat loss, civil unrest, illegal hunting, and ecological changes (climate change and habitat conversion).

How many left: 23,000 to 39,000 in the wild.

Unlike other members of the cat family, lions tend to live in a family group (pride) of between 20 to 30 members. Some prides have only one male, other up to four. Lions are incredibly territorial and will fight and very often kill any stray male wondering into their zone. The winner of this fight takes over the pride and dominance of the territory.

The majority of lions hunt at dusk, spending most of their days sleeping and recovering from the previous hunt. Usually, it is the females who do the hunting. Although male lions don’t really take part in the hunting, they eat their share of the kill before the rest of the pride. So goes the expression “the lion’s share”.

  • Weight: Males 186.55–225 kg (411.3–496.0 lb) in Southern Africa | Females 118.37–143.52 kg (261.0–316.4 lb) in Southern Africa.
  • Diet: Blue wildebeest, plains zebra, African buffalo, gemsbok and giraffe. Lions also hunt common warthog depending on availability.
  • Geographical location: Angola, Botswana, Mozambique, Tanzania, the Central African Republic, and South Sudan in sub-Saharan Africa, South Africa and India.
  • Cause of extinction: Habitat Destruction.

Great White Shark

The great white shark is the world’s largest, most fearsome predatory fish. Even though it has over 300 teeth, it never chews its food. Instead, it rips mouth-sized pieces of flesh off its prey and swallows it whole.

The sharks have a torpedo shaped body, making cruising through the water an effortless task. They are able to switch from cruising to high speeds of up to 56 km/h (35 mph) and dive down to depths of 1,200 m (3,900 ft).

The white shark is known to leap out of the water off the coast of South Africa, in False Bay. This act is known as breaching.

  • Size: Males 3.4 to 4.0 m (11 to 13 ft) long | Females 4.6 to 4.9 m (15 to 16 ft) long. The largest females have been verified up to 6.1 m (20 ft)
  • Weight: 522–771 kg (1,151–1,700 lb) on average.
  • Diet: Fish, dolphins, whales, seals, sea turtles and sea otters.
  • Geographical location: South Africa, Australia, New Zealand and North America. (Full list here.)
  • Cause of extinction: Hunting and being caught in nets as bycatch.

Hippopotamus

How many left: 115,000 to 130,000

Hippos are much bigger than most of us realize. They are in fact the second heaviest land mammal behind the elephant. During the day, hippos seek refuge from the baking sun by living in the water. However, when night falls, they head to land in search of soft, short grasses and fallen fruit.

Their eyes are situated on top of their head, which allows them to look out for enemies (mainly crocodiles), while lying low in the water.

  • Weight: 1,300 kg (2,870 lb) for males and females respectively. | Very large males can reach 2,000 kg (4,410 lb) and exceptional males can weigh 2,660 kg (5,860 lb) to 3,200 kg (7,050 lb)
  • Diet: Short aquatic grasses.
  • Geographical location: Democratic Republic of the Congo, Uganda, Tanzania and Kenya, north through to Ethiopia, Somalia and Sudan, west to The Gambia, and south to South Africa.
  • Cause of extinction: Unregulated hunting for their meat, skin, and teeth. Habitat loss.

Interesting Insights from the Bobwhite Quail!

The bobwhite quail can stand on its own as an interesting animal. But – the bobwhite quail also demonstrates some truly amazing biological concepts!

Precocial Young

Humans do not have precocial young. Human babies take years – if not decades – to develop and mature into adults. By contrast, many species of animals are born nearly completely developed – albeit slightly smaller than the adults.

Bobwhite quail chicks are ready to hit the ground running. Before they hatch, they start communicating with each other and their parents through their shells. By the time they break the shell, their leg muscles are fairly strong and the babies are ready to run through the underbrush with their parents. The chicks do take a few weeks to fly – but in every other regard, they are ready to take care of themselves.

Many other ground-dwelling birds give birth to precocial young. Unlike birds that nest in trees, this is often a requirement because there are too many predators on the ground. Geese, killdeer, ducks, and many other bird species must hatch prepared to run.

Faking Injury to Distract Predators

When a bobwhite quail nest is threatened by predators, the parents will actively try to lure a predator away with a specific display. The adults will feign injury – leaning heavily to one side and sticking out a wing.

Predators, attracted by the seemingly helpless prey, quickly move away from the undiscovered nest and chase the faking parent. As soon as the bobwhite quail is certain that the predator is far away enough from the nest, it will simply take flight and land in a tree to avoid the predator.

This behavior is seen in a large number of ground-nesting birds. While many animal moms will simply attack a predator, birds are much smaller and mostly defenseless. So, this clever trick of evolution allows them to get rid of a predator and protect their nest without a direct confrontation.

Conservation and Hunting

The bobwhite quail serves as an interesting case study of how hunting can both contribute and degrade natural environments.

One the one hand, bobwhite quail – as a species – have a distinct value to hunters and are thus reproduced in large numbers to meet demand. This will help ensure that the bobwhite quail does not go extinct.

At the same time, introducing bobwhite quail into new habitats can disrupt the delicate balance of an ecosystem. If the introduced bobwhites use up all of an important resource, local animal species might suffer. If bobwhite quail are introduced into the range of an endangered species, the move could ensure that species’ extinction.


Giant trevally

Caranx ignobilis , Peter Forsskål, 1775

The giant trevally (Caranx ignobilis), also known as the lowly trevally, barrier trevally, giant kingfish or ulua, is a species of large marine fish classified in the jack family, Carangidae. The giant trevally is distributed throughout the tropical waters of the Indo-Pacific region, with a range stretching from South Africa in the west to Hawaii in the east, including Japan in the north and Australia in the south. Two were documented in the eastern tropical Pacific in the 2010s (one captured off Panama and another sighted at the Galápagos), but it remains to be seen if the species will become established there.

The giant trevally is distinguished by its steep head profile, strong tail scutes, and a variety of other more detailed anatomical features. It is normally a silvery colour with occasional dark spots, but males may be black once they mature. It is the largest fish in the genus Caranx, growing to a maximum known size of 170 cm (67 in) and a weight of 80 kg (176 lbs). The giant trevally inhabits a wide range of marine environments, from estuaries, shallow bays and lagoons as a juvenile to deeper reefs, offshore atolls and large embayments as an adult. Juveniles of the species are known to live in waters of very low salinity such as coastal lakes and upper reaches of rivers, and tend to prefer turbid waters.

The giant trevally is an apex predator in most of its habitats, and is known to hunt individually and in schools. The species predominantly takes various fish as prey, although crustaceans, cephalopods and molluscs make up a considerable part of their diets in some regions.

The giant trevally employs novel hunting strategies, including shadowing monk seals to pick off escaping prey, as well as using sharks to ambush prey. Footage released in 2017 on Blue Planet II revealed a group of approximately 50 giant trevally hunting terns, specifically fledglings still learning to fly and which crash land in the water, as well as both fledglings and adults unfortunate enough to fly low enough for the fish to pounce on them, in Farquhar Atoll in the Seychelles.

The giant trevally reproduces in the warmer months, with peaks differing by region. Spawning occurs at specific stages of the lunar cycle, when large schools congregate to spawn over reefs and bays, with reproductive behaviour observed in the wild. The fish grows relatively fast, reaching sexual maturity at a length of around 60 cm at three years of age.

The giant trevally is both an important species to commercial fisheries and a recognised gamefish, with the species taken by nets and lines by professionals and by bait and lures by anglers. Catch statistics in the Asian region show hauls of 4, 000&ndash10, 000 tonnes, while around 10, 000 lbs of the species is taken in Hawaii each year. The species is considered poor to excellent table fare by different authors, although ciguatera poisoning is common from eating the fish. Dwindling numbers around the main Hawaiian Islands have also led to several proposals to reduce the catch of fish in this region.

Taxonomy and phylogeny

The giant trevally is classified within the genus Caranx, one of a number of groups known as the jacks or trevallies. Caranx itself is part of the larger jack and horse mackerel family Carangidae, which in turn is part of the order Carangiformes.

The giant trevally was first scientifically described by the Swedish naturalist Peter Forsskål in 1775 based on specimens taken from the Red Sea off both Yemen and Saudi Arabia, with one of these designated to be the holotype. He named the species Scomber ignobilis, with the specific epithet Latin for "unknown", "obscure" or "ignoble". It was assigned to the mackerel genus Scomber, where many carangids were placed before they were classified as a separate family. This later revision in classification saw the species moved to the genus Caranx, where it has remained. Even after its initial description, the giant trevally (and the bigeye trevally) were often confused with the Atlantic crevalle jack, Caranx hippos, due to their superficial similarity, which led to some authors claiming the crevalle jack had a circumtropical distribution. After Forsskål's initial description and naming, the species was independently renamed three times as Caranx lessonii, Caranx ekala and Carangus hippoides, all of which are now considered invalid junior synonyms. The latter of these names once again highlighted the similarity with the crevalle jack, with the epithet hippoides essentially meaning "like Carangus hippos", which was the crevalle jack's Latin name at that time. Despite the resemblance with the crevalle jack, the two species have never been phylogenetically compared, either morphologically or genetically, to determine their relationship.

C. ignobilis is most commonly referred to as the giant trevally (or giant kingfish) due to its large maximum size, with this often abbreviated to simply GT by many anglers. Other names occasionally used include lowly trevally, barrier trevally, yellowfin jack (not to be confused with Hemicaranx leucurus), Forsskål's Indo-Pacific jack fish and Goyan fish. In Hawaii, the species is almost exclusively referred to as ulua, often in conjunction with the prefixes black, white, or giant. Due to its wide distribution, many other names for the species in different languages are also used. In the Philippines, the species is referred to as talakitok. Some success has been achieved in raising giant trevally commercially in small fish farms there, typically to an age of seven months.

Description

The giant trevally is the largest member of the genus Caranx, and the fifth-largest member of the family Carangidae (exceeded by the yellowtail amberjack, greater amberjack, leerfish and rainbow runner), with a recorded maximum length of 170 cm and a weight of 80 kg. Specimens this size are very rare, with the species only occasionally seen at lengths greater than 80 cm. It appears the Hawaiian Islands contain the largest fish, where individuals over 100 lbs are common. Elsewhere in the world, only three individuals over 100 lbs have been reported to the IGFA.

The giant trevally is similar in shape to a number of other large jacks and trevallies, having an ovate, moderately compressed body with the dorsal profile more convex than the ventral profile, particularly anteriorly. The dorsal fin is in two parts, the first consisting of eight spines and the second of one spine followed by 18 to 21 soft rays. The anal fin consists of two anteriorly detached spines followed by one spine and 15 to 17 soft rays. The pelvic fins contain 1 spine and 19 to 21 soft rays. The caudal fin is strongly forked, and the pectoral fins are falcate, being longer than the length of the head. The lateral line has a pronounced and moderately long anterior arch, with the curved section intersecting the straight section below the lobe of the second dorsal fin. The curved section of the lateral line contains 58-64 scales, while the straight section contains none to four scales and 26 to 38 very strong scutes. The chest is devoid of scales with the exception of a small patch of scales in front of the pelvic fins. The upper jaw contains a series of strong outer canines with an inner band of smaller teeth, while the lower jaw contains a single row of conical teeth. The species has 20 to 24 gill rakers in total and 24 vertebrae are present.

The eye is covered by a moderately well-developed adipose eyelid, and the posterior extremity of the jaw is vertically under or just past the posterior margin of the pupil. The eye of the giant trevally has a horizontal streak in which ganglion and photoreceptor cell densities are markedly greater than the rest of the eye. This is believed to allow the fish to gain a panoramic view of its surroundings, removing the need to constantly move the eye, which in turn will allow easier of detection of prey or predators in that field of view.

At sizes less than 50 cm, the giant trevally is a silvery-grey fish, with the head and upper body slightly darker in both sexes. Fish greater than 50 cm show sexual dimorphism in their colouration, with males having dusky to jet-black bodies, while females are a much lighter coloured silvery-grey. Individuals with darker dorsal colouration often also display striking silvery striations and markings on the upper part of their bodies, particularly their backs. Black dots of a few millimetres in diameter may also be found scattered all over the body, although the coverage of these dots varies between widespread to none at all. All the fins are generally light grey to black, although fish taken from turbid waters often have yellowish fins, with the anal fin being the brightest. The leading edges and tips of the anal and dorsal fins are generally lighter in colour than the main part of the fins. There is no black spot on the operculum. Traces of broad cross-bands on the fish's sides are occasionally seen after death. The fishes have been known to prey and eat on the dead fish.

Distribution

The giant trevally is widely distributed throughout the tropical and subtropical waters of the Bay of Bengal, Indian and Pacific Oceans, ranging along the coasts of three continents and many hundreds of smaller islands and archipelagos. In the Indian Ocean, the species' westernmost range is the coast of continental Africa, being distributed from the southern tip of South Africa north along the east African coastline to the Red Sea and Persian Gulf. Its range extends eastwards along the Asian coastline, including Pakistan, India and into Southeast Asia, the Indonesian Archipelago and northern Australia. The southernmost record from the west coast of Australia comes from Rottnest Island, not far offshore from Perth. Elsewhere in the Indian Ocean, the species has been recorded from hundreds of small island groups, including the Maldives, Seychelles, Madagascar and the Cocos (Keeling) Islands.

The giant trevally is abundant in the central Indo-Pacific region, found throughout all the archipelagos and offshore islands including Indonesia, Philippines and Solomon Islands. Along continental Asia, the species has been recorded from Malaysia to Vietnam, but not China. Despite this, its offshore range does extend north to Hong Kong, Taiwan and southern Japan. In the south, the species reaches as far south as New South Wales in Australia and even to the northern tip of New Zealand in the southern Pacific. Its distribution continues throughout the western Pacific, including Tonga, Western Samoa and Polynesia, with its easternmost limits known to be the Pitcairn and Hawaiian Islands.

Habitat

The giant trevally inhabits a very wide range of offshore and inshore marine environments, with the species also known to tolerate the low salinity waters of estuaries and rivers. It is a semipelagic fish known to spend time throughout the water column, but is mostly demersal in nature.

The species is most common in shallow coastal waters in a number of environments, including coral and rocky reefs and shorefaces, lagoons, embayments, tidal flats and channels. They commonly move between reef patches, often over large expanses of deeper sand and mud bottoms between the reefs. Older individuals tend to move to deeper seaward reefs, bomboras and drop-offs away from the protection of fringing reefs, often to depths greater than 80 m. Large individuals, however, often return to these shallower waters as they patrol their ranges, often to hunt or reproduce. In Hawaii, the juvenile to subadult giant trevally is the most common large carangid in the protected inshore waters, with all other species apparently preferring the outer, less protected reefs. It is also easily attracted to artificial reefs, where studies have found it to be one of the predominant species around these structures in Taiwan.

Juvenile to subadult giant trevally are known to enter and inhabit estuaries, the upper reaches of rivers and coastal lakes in several locations, including South Africa, Solomon Islands, Philippines, India, Taiwan, Thailand, northern Australia, and Hawaii. In some of these locations, such as Australia, it is a common and relatively abundant inhabitant, while in others, including South Africa and Hawaii, it is much rarer in estuaries. The species has a wide salinity tolerance, as evident from the ranges from which juvenile and subadult fish in South African estuaries have been recorded 0.5 to 38 parts per thousand (ppt), with other studies also showing tolerance levels of less than 1 ppt. In these estuaries, the giant trevally is known from both highly turbid, dirty water to clean, high visibility waters, but in most cases, the species prefers the turbid waters. Younger fish apparently actively seek out these turbid waters, and when no estuaries are present, they live in the turbid inshore waters of bays and beaches. These young fish eventually move to inshore reefs as they mature, before again moving to deeper outer reefs.

In the Philippines, a population of giant trevally inhabit (and were once common in) the landlocked fresh waters of the formerly saltwater Taal Lake, and are referred to as maliputo to distinguish them from the marine variant (locally named talakitok). Along with Taal Volcano and Taal Lake, the maliputo is prominently featured on the reverse side of the newly redesigned Philippine 50 peso bill.

Biology and ecology

The giant trevally is a solitary fish once it reaches sexual maturity, only schooling for the purposes of reproduction and more rarely for feeding. Juveniles and subadults commonly school, both in marine and estuarine environments. Observations from South African estuaries indicate the schools of smaller juveniles tend not to intermingle with schools of other species, but larger subadults are known to form mixed-species schools with the brassy trevally. Research has been conducted on the movements of larger fish around their habitats, as well as the movement between habitats as the species grows, to understand how marine reserves impact on the species. Adult giant trevally are known to range back and forth up to 9 km along a home range, with some evidence of diel and seasonal shifts in habitat use. In the Hawaiian Islands, giant trevally do not normally move between atolls, but have specific core areas where they spend most their time. Within these core areas, habitat shifts during different times of the day have been recorded, with the fish being most active at dawn and dusk, and usually shifting location near sunrise or sunset. Furthermore, large seasonal migrations appear to occur for the purpose of aggregating for spawning, with this also known from the Solomon Islands. Despite not moving between atolls, they do make periodic atoll-wide journeys of up to 29 km. Long-term studies show juveniles can move up to 70 km away from their protected habitats to outer reefs and atolls. The giant trevally is one of the most important apex predators in its habitats, both as adults on reefs and as juveniles in estuaries. Observations in relatively untouched waters of the northwestern Hawaiian Islands showed the giant trevally was of high ecological importance, constituting 71% of the apex predator biomass, and was the dominant apex predator. This number is considerably less in heavily fished Hawaiian waters. The species is prey to sharks, especially when small. Conversely, adult giant trevallies, either singles or pairs, have been recorded attacking sharks (like blacktip reef shark) by ramming them repeatedly with their head. The shark, sometimes even larger than the trevally, may die from the attack. The reason for this behavior is unclear, but the giant trevally does not attempt to eat the dead shark. Rarely, they have been recorded behaving in the same way towards humans: A spearfisher in Hawaii broke three ribs when rammed by a giant trevally. Large giant trevallies have been recorded as a host of the sharksucker, Echeneis naucrates, a fish which is normally seen attached to the undersides of sharks.

Diet and feeding

The giant trevally is a powerful predatory fish, from the estuaries it inhabits as a juvenile to the outer reefs and atolls it patrols as an adult. Hunting appears to occur at different times of the day in different areas of its range off South Africa it is most active during the day, especially at dawn and dusk, while off Zanzibar and Hong Kong, it is nocturnal in its habits. The species' diets have been determined in several countries and habitats their diets generally vary slightly by locations and age. In all but one study (which was of juveniles), the giant trevally dominantly takes other fishes, with various crustaceans, cephalopods and occasionally molluscs making the remainder of the diet. In Hawaii, the species has a predominantly fish-based diet consisting of Scaridae and Labridae, with crustaceans, including lobsters, and cephalopods (squid and octopus) making up the remaining portion. The large number of reef fishes suggests it spends much of its time foraging over shallow-water reef habitats, but the presence of squid and the schooling carangid Decapterus macarellus indicates exploitation of more open-water habitats, as well. Off Africa, the diet is similar, consisting mostly of fish including eels, with minor squid, octopus, mantis shrimp, lobsters and other crustaceans. Younger fish inside Kaneohe Bay, Hawaii showed the only instance where crustaceans were preferred over fish stomatopods, shrimp and crabs were the most common prey taken at 89% of stomach content by volume, with fish, mostly of the family Blennidae, making up only 7% of the stomach contents. Estuarine fish in both Hawaii and Australia have mostly fish-based diets, with crustaceans such as prawns and amphipods also of importance, and they are known to take more novel prey, such as spiders and insects, in these habitats. Juvenile turtles and dolphins were reported being found within the stomach contents of larger giant trevally. Studies of different size classes of fish have found their diets change with age in some locations, with the changes relating to an increased volume of fish taken.

Giant trevally also feed on fledgling sooty terns on Farquhar Atoll snatching them from the water surface and even jumping acrobatically to catch them in the air as seen on the BBC documentary Blue Planet II, episode 1. So far this behaviour has not been observed elsewhere.

Studies in controlled environments on the giant trevally's feeding strategies have found hunting in schools increases their capture efficiency, but is not necessary for an individual's survival. When a school is formed during feeding, one individual will take a leading position, with others trailing behind it. Several individuals will attack the prey school, striking and stunning the prey, with the leading individual generally being more successful. Some individuals act individually and opportunistically within the school if one of the prey fish becomes isolated, with the main advantage of schooling appearing to be the ability to further break up and isolate prey schools. The only time hunting in schools is a disadvantage is when only isolated prey are present, such as close to a reef here, an individual hunter has a greater probability of capturing it than if a group is present. Another hunting strategy of the giant trevally is to 'escort' monk seals, a behavior which has been observed near the Hawaiian Islands. The trevally swim close by the seal, and when the seal stops to forage, the trevally positions its mouth inches away from the seal. If a prey item is disturbed, the trevally will attempt to steal the prey from the seal, which routinely does occur. The seal does not appear to gain any benefit from this relationship, and it is thought juvenile seals being followed in this way may be outcompeted by the larger fish. A similar strategy has been employed by fish in the presence of large reef sharks, as they use the larger animal as a tool to ambush prey. The opportunistic nature of giant trevally has also been made evident by studies on the mortality rate of undersized or egg-bearing lobsters released from traps at the water's surface of the Hawaiian Islands. The fish are efficient predators of these crustaceans, with individuals often seizing a lobster before it could sink to the seafloor after being released, or attacking before the lobster moves into a defensive position. Some bolder, large individuals are even known to eat the lobster head first when it is in a defensive stance.

Life history

The giant trevally reaches sexual maturity at 54 to 61 cm in length and three to four years of age, although many authors narrow this down to 60 cm and three years of age. Sex ratio estimates from the Hawaiian Islands suggest the population is slightly skewed toward females, with the male:female ratio being 1:1.39. Spawning occurs during the warmer months in most locations, although the exact dates differ by location. In southern Africa, this occurs between July and March, with a peak between November and March in the Philippines between December and January, with a lesser peak during June and in Hawaii between April and November, with a major peak during May to August. Lunar cycles are also known to control the spawning events, with large schools forming in certain locations at specific phases of the moon in Hawaii and the Solomon Islands. Locations for spawning include reefs, the reef channels and offshore banks. Sampling of schools prior to spawning suggests the fish segregate into schools of only one sex, although the details are still unclear. Observations in the natural habitat found spawning occurred during the day immediately after and just before the change of tide when there were no currents. Giant trevally gathered in schools of over 100 individuals, although ripe individuals occurred slightly deeper around 2&ndash3 m above the seabed in groups of three or four, with one silver female being chased by several black males. Eventually, a pair would sink down to a sandy bottom, where eggs and sperm were released. The fish then diverged and swam away. Each individual appears to spawn more than once in each period, with only part of the gonads ripe in spawners. Fecundity is not known, although females are known to release several thousand eggs on capture during the spawning process. Eggs are described as pelagic and transparent in nature.

The giant trevally's early larval stages and their behaviour have been extensively described, with all fins having formed by at least 8 mm in length, with larvae and subjuveniles being silver with six dark vertical bars. Laboratory populations of fish show a significant variability in the length at a certain age, with the average range being around 6.5 mm. Growth rates in larvae between 8.0 and 16.5 mm are on average 0.36 mm per day. The speed at which larvae swim increases with age from 12 cm/s at 8 mm in length to 40 cm/s at 16.5 mm, with size rather than age a better predictor of this parameter. Size is also a better predictor of endurance in larvae than age. These observations suggest the species becomes an effective swimmer (is able to swim against a current) around 7&ndash14 mm. No obvious relationships with age and either swimming depth or trajectory have been found. Larvae appear to also opportunistically feed on small zooplankton while swimming. The larvae actively avoid other large fish, and jellyfish are occasionally used as temporary cover. Larvae have no association with reefs, and appear to prefer to live pelagically. Daily growth is estimated at between 3.82 and 20.87 g/day, with larger fish growing at a more rapid rate. Length at the age of one year is 18 cm, at two years is 35 cm and by three years, the fish is around 50 to 60 cm. The use of von Bertalanffy growth curves fitted to observed otolith data show an individual of around 1 m in length is about eight years old, while a 1.7 m fish would be around 24 years old. The maximum theoretical length of the species predicted by the growth curves is 1.84 m, but the largest reported individual was 1.7 m long. As previously mentioned, as the giant trevally grows, it shifts from turbid inshore waters or estuaries to reefs and lagoons in bays, moving finally to outer reefs and atolls.

A hybrid of C. ignobilis and C. melampygus (bluefin trevally) has been recorded from Hawaii. The specimen was initially thought to be a bluefin trevally of world-record size, but was later rejected when it was discovered to be a hybrid. Initial evidence of hybridisation was morphological characteristics intermediate to the two species later genetic tests confirmed it was indeed a hybrid. The two species are known to school together, including at spawning time, which was considered to be the reason for hybridisation.

Relationship to humans

The giant trevally has been used by humans since prehistoric times, with the oldest known records of the capture of this species by Hawaiians, whose culture held the fish in high regard. The ulua, as the fish is known to Hawaiians, was likened to a fine man and strong warrior, which was the cause of a ban on women eating the species in antiquity. The species was often used in Hawaiian religious rites, and took place of a human sacrifice when none was available. Culturally, the fish was seen as a god, and treated as gamefish which commoners could not hunt. There are many mentions of ulua in Hawaiian proverbs, all generally relating to the strength and warrior-like qualities of the fish. The Hawaiians considered the fish to be of excellent quality, with white, firm flesh. Despite this, intrusions of giant trevally into modern-day fishponds used by Hawaiians for rearing fish are unwelcome being a predator, it eats more than it is worth at market.

The giant trevally is of high importance to modern fisheries throughout its range, although quantifying the amounts taken is very difficult due to the lack of fishery statistics kept in most of these countries. Hawaii has the best-kept statistics, where the 1998 catch consisted of 10, 194 pounds of giant trevally worth around US$12, 000. Historically, the species has been taken in far greater numbers, and has been an important food, market and game fish since the early 1900s. However, their exploitation has seen the landings of the species decrease by over 84% since the turn of the century, declining from 725, 000 lb to 10, 000 lb in recent catches. FAO statistics of the Asian region record catches between 4, 000 and 10, 000 tonnes between 1997 and 2007, although this excludes most fisheries which are not monitored or do not discriminate between trevally species. The giant trevally is commercially caught by a number of methods, including hook and line, handlines, gill nets and other types of artisanal traps. The species has also successfully been bred for aquaculture purposes in Taiwan. It is sold at market fresh, frozen, salted, and smoked, and as fishmeal and oil.

The giant trevally is considered one of the top gamefish of the Indo-Pacific region, having outstanding strength, speed and endurance once hooked. It can be taken by many methods, including baits of cut or live fish and squid, as well as a wide array of lures. The species is commonly taken on bibbed plugs, minnows, spoons, jigs and poppers, soft plastic lures and saltwater flies. In recent years, the development of both jigging and surface-popping techniques has seen the giant trevally become an extremely popular candidate for catch and release fishing, with many charter operators based around this concept. The species is also popular with spearfishermen throughout its range. The species' edibility has been rated from poor to excellent by different authors, although numerous cases of ciguatera poisoning have been reported from the species. Detailed tests on a large (1 m) specimen taken from Palmyra Island showed the toxicity of the fish's flesh, liver and washed intestinal tract produced no or weakly positive symptoms to laboratory mice, but the digested contents of the intestine were lethal. The authors argued, based on this test, the flesh of giant trevally was safe to consume. However, analysis of case studies in which ciguatera poisoning was reported after eating the fish suggested an accumulative effect occurs with repeated consumption and tests like the one outlined above are not reliable, as the toxin appears to be distributed haphazardly throughout each fish. Since 1990, giant trevally taken from the main Hawaiian islands have been blocked from sale by auction internationally due to concerns over liability from ciguatera poisoning.

Conservation

A decline in giant trevally numbers around inhabited regions has been well documented in Hawaii, with both catch data as presented above and ecological studies showing this decrease in numbers. A biomass study in the Hawaiian Islands indicates the main Hawaiian Islands are heavily depleted in the species, which in untouched ecosystems comprises 71% of the apex predator biomass. In contrast, it comprises less than 0.03% of the apex biomass in exploited habitats, with only a single fish observed during the course of this research study. Prior to this, a 1993 report suggested the population around the main Hawaiian islands were not stressed, though several biological indicators suggested to the contrary. This was due to the highly size-selective nature of the fishery, which theoretically should prevent a decrease in numbers. Despite this, populations have decreased, and in light of their continued falling abundance in Hawaii, several recommendations, including banning the commercial take of the species, increasing minimum lengths and decreasing bag limits for anglers, as well as reassessment of protected areas for the species, have been proposed by officials. The species (nor any other carangid) has not been assessed by the IUCN.

Some recreational fishing groups are also promoting a catch and release practice for the giant trevally, with this becoming an increasingly popular option for charter boat operators, who have also begun to tag giant trevally for scientific purposes. At large sizes, the species is more likely to be ciguatoxic, so if the fish is kept, it must be disposed of or sent to a taxidermist if it is a trophy fish. A catch and release approach has also been adopted by operators outside Hawaii, with Australian operators who target the species by popping and jigging rarely keeping any fish. Careful fish handling techniques have also been implemented by anglers so as not to damage the fish such techniques include supporting the fish's weight, using barbless single, rather than treble, hooks and restricting the time the fish spends out the water to a minimum.

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Lonicera Fly

Flies are kind of odd, but sometimes it is good to push the creation of more due to how important they can be for an entire ecosystem. Flys do serve a role in our world, but we usually tend to get all we need from the current. Why would anyone want to create a hybrid version of one? Funny enough, scientists are not responsible for the creation of the Lonicera Fly. This is a North American Fruit Fly that was first introduced in America at some point in the last 250 years.

[Image via BugGuide.net] Many believe it was brought over to America on ornamental plants, making the origin likely somewhere in Europe. These particular flies tend to feed on berries from honeysuckles, also introduced in America in the last 250 years. It is widely assumed that flies came with the honeysuckle, and it could be that some breeding took place between both Blueberry and Snowberry maggots. They are now pretty widespread in North America.


What Does a Black Bear Eat?

Bears are called omnivores because they eat both plant and animals. A Florida black bear's diet varies, but usually consists of 80% plants, 15% insects, and 5% animal matter.

The vegetative part of their diet is made up of grasses and leaves, as well as mast. Hard mast is the fruit of forest trees like acorns, hickory and other nuts, while soft mast is fruits such as saw palmetto, holly, and pokeweed berries.

They also feed on colonial insects such as wasps, bees, termites, and ants.

The small meat portion of their diet is things that are dead (carrion) or play dead (e.g. armadillos, opossums) and are mostly obtained from scavenging.

FWC has compiled an extensive list of natural food items that Florida bears are known to eat.

The black bear diet varies seasonally and yearly depending on fluctuations in plant productivity but it is also based on geographic variation from one region of Florida to the next. For example, saw palmetto berries are a high portion of bear diets in the Osceola population, but insignificant in the Apalachicola population where the berries are not readily available. For more information on each region's population, please see our distribution map.

During the summer months, bears eat about 5,000 calories a day or the equivalent of two large cheese pizzas. But as fall begins bears start preparing for winter by going through a process of increased feeding called hyperphagia. Both sexes will forage up to 18 hours a day and gain up to 1½ times their summer weight. This weight gain is because they are taking in up to 20,000 calories a day¹ or the equivalent of 8½ large cheese pizzas. Another way to look at it is 20,000 calories is what the average person eats in 10 days! Gaining weight allows bears to make it through the leaner winter months, where both male and female bears will lose weight due to the lack of abundant food items. Once freezing temperatures set in bears will begin denning. Bears can lose up to 25% of their body weight while denning.

A bear is always looking for food, and is not very particular as to what foods they will eat. In addition, the bear can smell food up to a mile away. A bear's search for food is the primary cause of conflicts with people. Bears are often attracted to smells of garbage, beeyards, pet foods, barbeque grills, wildlife feeders, and other temptations bring them closer to human homes, which can result in property damage and safety concerns for both people and bears. Bears that habitually feed on human supplied foods such as garbage, wildlife feed, or pet food tend to be abnormally large.

It is important to know how to keep our Florida bears wild and away from your home. For more information, please visit Living With Bears.