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Why aren't native predators in Australia able to handle the mice problem?

Why aren't native predators in Australia able to handle the mice problem?


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Australia is currently dealing with a mouse infestation problem, but Australia is awash with different types of predators that presumably eat lots of mice like animals. Snakes in particular are well suited to kill mice, especially in close quarters. Snakes can fit in places most other predators can't due to their size. Additionally large invertebrates (like huntsman spiders) should also be able to take on some of the mouse load.

And it would be one thing if this was the first time the population ever boomed like this, but mice population booms have apparently have happened since Australia has existed. So why aren't we seeing large spikes in those predators when mice populations boom like this?


The mice aren't invading Australia, they are invading the wheat producing zones, where the tractors are leveling the land and putting on pesticides. The local frog, amphibian and snake populations downstream of the farmer's fields is strongly affected by the farmland, and so are the birds of prey, if they weather the pesticide use, they have to hide in dense trees, hollow logs, caves, and old barns, which are very lacking in Australian farmland.

If the government enforced laws for field edge habitats for local ecology, then there would be less mice.

Have a look at the map of wheat producing areas. Rodent Outbreaks: Ecology and Impacts pages 225-238 PDF Google book

The map of mice infestations:

From pestsmart.org.au, though no longer available.

and a map of Australian climate:

wikimedia


Questions regarding regulated functions

I have a few quick questions regarding regulated functions:

Firstly, I'll state the definition I have been given:

Definition: Let $I=[a,b]$ be a compact interval. Then $f:I o mathbb$ is called regulated if $exists (f_n)_<>>$ of step functions $f_n in S(I)$ such that $f_n o f$ uniformly. ($S(I)$ denotes the set of all step functions.

$1)$ Are continuous functions regulated?

$2)$ Are piecewise-continuous functions regulated?

$3)$ Are step functions regulated?

A brief explanation for each would be appreciated.

I'm hoping the answer to all three is "yes" as that would mean I have understood a few key concepts in my real analysis course.

$C(I)subset PC(I) subset R(I)$ and $S(I)subset PC(I)$

Where $C(I)$ denotes the set of all continous functions, $PC(I)$ denotes the set of all piecewise continuous functions and $R(I)$ denotes the set of all regulated functions.


1 Answer 1

I am not a native speaker but at school I was taught that you should use "that" for defining relative clauses, whereas both "which" and "that" are allowed for non-defining relative clauses.

Therefore: "I really like this pencil case which Rose gave me." Here, the relative clause only adds information about a pencil case that is already known (this pencil case). In this case, as far as I know, you can also use "that". The relative pronoun cannot be omitted.

"I really like the pencil case that Rose gave me." Here the relative clause defines the pencil case: I am talking about the pencil case that Rose gave me, not about another one. In this case, it is compulsory to use "that". Alternatively, you can omit "that" altogether: "I really like the pencil case Rose gave me."

This is at least the rules that I recall from school and I may be wrong. I also do not know if the American and the British use differ on this since I am neither from Great Britain nor from the United States.


1 Answer 1

There are a number of different strategies you can apply, depending on the technical constraints that you have. For example, you can make the table more interactive and allow the cell to show occupancy values when you hover over the cell. Given a specific constraint or requirements will allow people to provide a better or less generic response. However, some things to think about include:

  • Need to see both values at the same time for the entire heatmap: will this be too much information for the user to process and make it harder to pick up the patterns and trends you are looking for?
  • How the information is used to make decisions: what kind of insights are you looking for and how will it help the person viewing the information to make a decision? Are there additional information that will support this decision that is not displayed as well?
  • Will there be additional changes to the dataset: are you going to be adding more rows to the heatmap in the future if there are more locations to analyze? Will you try to breakdown the time into finer increments? Will you be adding additional contextual information to filter the information (e.g. days of the week)

I think letting the use case determine the design is better than making a design decision without more details. Sometimes it is a compromise you have to make between the amount of information you want to display and what you actually need to use it for in different situations. If you can update your question I am sure you will get closer to the answer you are looking for.


Marsupial homeland

And it turns out, the oldest known marsupials are actually from North America, where they evolved during the Cretaceous period after splitting off from placental mammals at least 125 million years ago, Beck said.

These ancient marsupials appeared to flourish in North America, populating what was then the supercontinent Laurasia with about 15 to 20 different marsupial species, all of which are now extinct, Beck said. It's unclear why these marsupials did well. But for some reason, at about the time that the nonavian dinosaurs went extinct, about 66 million years ago, the marsupials made their way down to South America. At that time, North and South America weren't connected as they are today. But the two continents were very close, and a land bridge or a series of islands may have linked them. This connection allowed all kinds of animals to expand their stomping grounds.

Once in South America, marsupials and their close relatives had a field day, diversifying like crazy within 2 million to 3 million years after arriving, Beck said. For instance, marsupials and their close relatives evolved into bear- and weasel-size carnivores, and one even evolved saber teeth. Others evolved to eat fruits and seeds.

"What's happening in South America is they're evolving to fill the kinds of niches that in the northern continents certainly were filled by placental mammals," Beck said.

Many of these marsupials went extinct between then and now, but South America is still a marsupial hotspot today. There are more than 100 species of opossums, seven species of shrew opossums and the adorable monito del monte (Dromiciops gliroides), whose Spanish name translates to "little monkey of the mountain."

On a side note, within the last 1 million years, one of South America's opossums traveled north and now lives in North America. This is the Virginia opossum (Didelphis virginiana), the only marsupial living north of Mexico, Beck said.

Also, opossums belong to a different order than possums. Possums are native to Australia and New Guinea, are closely related to kangaroos, and have a number of anatomical differences, such as enlarged lower incisors, that the South American opossum lacks, Beck said.

So, how did marsupials get from South America to Australia? [Will There Ever Be Another Pangea?]


Predict and control

Mr Barr hoped that introducing more owls would help predict and control house mice populations.

He said studies undertaken in other similar Mediterranean climates in Israel, Spain and the USA showed promise.

"The science is there," Mr Barr said.

"By enhancing avian predators, and that's anything that hunts rodents … that can aid in reducing rodent damage in agricultural settings.

"What we need to do in SA and Australia-wide is to test that hypothesis in our local area and our Australian agricultural settings."


How species typically become invasive?

An exotic species can become invasive when it is introduced into a new environment that exists in a climate that is very similar to where it is native. Because a potentially invasive organism is already so well-adapted to the climate of its new environment, it can then take advantage of available niches, where it reproduces, invades, and proliferates within local ecosystems because it now has no natural predators to limit its population levels.

Due to the increased levels of global economic trade activity and travel that is occurring around the world today between regions that were once isolated from one another in the past, there has been an increase in exotic species being introduced around the world.

These exotic species introductions can be intentional, such as the Purple Loosestrife in the United States, or unintentional, such as the Emerald Ash Borer in the United States and the Norway Rat throughout most of the world.

Sources of exotic species introductions include:

  • the ballast water of ships
  • the intentional and unintentional release of exotic species into the environment by the public
  • the pet trade
  • the horticultural industry
  • the aquaculture industry

Contents

The distinguishing feature of the rodents is their pairs of continuously growing, razor-sharp, open-rooted incisors. [1] These incisors have thick layers of enamel on the front and little enamel on the back. [2] Because they do not stop growing, the animal must continue to wear them down so that they do not reach and pierce the skull. As the incisors grind against each other, the softer dentine on the rear of the teeth wears away, leaving the sharp enamel edge shaped like the blade of a chisel. [3] Most species have up to 22 teeth with no canines or anterior premolars. A gap, or diastema, occurs between the incisors and the cheek teeth in most species. This allows rodents to suck in their cheeks or lips to shield their mouth and throat from wood shavings and other inedible material, discarding this waste from the sides of their mouths. [4] Chinchillas and guinea pigs have a high-fiber diet their molars have no roots and grow continuously like their incisors. [5]

In many species, the molars are relatively large, intricately structured, and highly cusped or ridged. Rodent molars are well equipped to grind food into small particles. [1] The jaw musculature is strong. The lower jaw is thrust forward while gnawing and is pulled backwards during chewing. [2] Rodent groups differ in the arrangement of the jaw muscles and associated skull structures, both from other mammals and amongst themselves. The Sciuromorpha, such as the eastern grey squirrel, have a large deep masseter, making them efficient at biting with the incisors. The Myomorpha, such as the brown rat, have enlarged temporalis muscles, making them able to chew powerfully with their molars. The Hystricomorpha, such as the guinea pig, have larger superficial masseter muscles and smaller deep masseter muscles than rats or squirrels, possibly making them less efficient at biting with the incisors, but their enlarged internal pterygoid muscles may allow them to move the jaw further sideways when chewing. [6] The cheek pouch is a specific morphological feature used for storing food and is evident in particular subgroups of rodents like kangaroo rats, hamsters, chipmunks and gophers which have two bags that may range from the mouth to the front of the shoulders. [7] True mice and rats do not contain this structure but their cheeks are elastic due to a high degree of musculature and innervation in the region. [8]

While the largest species, the capybara, can weigh as much as 66 kg (146 lb), most rodents weigh less than 100 g (3.5 oz). Rodents have wide-ranging morphologies, but typically have squat bodies and short limbs. [1] The fore limbs usually have five digits, including an opposable thumb, while the hind limbs have three to five digits. The elbow gives the forearms great flexibility. [3] The majority of species are plantigrade, walking on both the palms and soles of their feet, and have claw-like nails. The nails of burrowing species tend to be long and strong, while arboreal rodents have shorter, sharper nails. Rodent species use a wide variety of methods of locomotion including quadrupedal walking, running, burrowing, climbing, bipedal hopping (kangaroo rats and hopping mice), swimming and even gliding. [3] Scaly-tailed squirrels and flying squirrels, although not closely related, can both glide from tree to tree using parachute-like membranes that stretch from the fore to the hind limbs. [9] The agouti is fleet-footed and antelope-like, being digitigrade and having hoof-like nails. The majority of rodents have tails, which can be of many shapes and sizes. Some tails are prehensile, as in the Eurasian harvest mouse, and the fur on the tails can vary from bushy to completely bald. The tail is sometimes used for communication, as when beavers slap their tails on the water surface or house mice rattle their tails to indicate alarm. Some species have vestigial tails or no tails at all. [1] In some species, the tail is capable of regeneration if a part is broken off. [3]

Rodents generally have well-developed senses of smell, hearing, and vision. Nocturnal species often have enlarged eyes and some are sensitive to ultraviolet light. Many species have long, sensitive whiskers or vibrissae for touch or "whisking". Some rodents have cheek pouches, which may be lined with fur. These can be turned inside out for cleaning. In many species, the tongue cannot reach past the incisors. Rodents have efficient digestive systems, absorbing nearly 80% of ingested energy. When eating cellulose, the food is softened in the stomach and passed to the cecum, where bacteria reduce it to its carbohydrate elements. The rodent then practices coprophagy, eating its own fecal pellets, so the nutrients can be absorbed by the gut. Rodents therefore often produce a hard and dry fecal pellet. [1] In many species, the penis contains a bone, the baculum the testes can be located either abdominally or at the groin. [3]

Sexual dimorphism occurs in many rodent species. In some rodents, males are larger than females, while in others the reverse is true. Male-bias sexual dimorphism is typical for ground squirrels, kangaroo rats, solitary mole rats and pocket gophers it likely developed due to sexual selection and greater male-male combat. Female-bias sexual dimorphism exists among chipmunks and jumping mice. It is not understood why this pattern occurs, but in the case of yellow-pine chipmunks, males may have selected larger females due to their greater reproductive success. In some species, such as voles, sexual dimorphism can vary from population to population. In bank voles, females are typically larger than males, but male-bias sexual dimorphism occurs in alpine populations, possibly because of the lack of predators and greater competition between males. [10]

One of the most widespread groups of mammals, rodents can be found on every continent except Antarctica. They are the only terrestrial placental mammals to have colonized Australia and New Guinea without human intervention. Humans have also allowed the animals to spread to many remote oceanic islands (e.g., the Polynesian rat). [3] Rodents have adapted to almost every terrestrial habitat, from cold tundra (where they can live under snow) to hot deserts.

Some species such as tree squirrels and New World porcupines are arboreal, while some, such as gophers, tuco-tucos, and mole rats, live almost completely underground, where they build complex burrow systems. Others dwell on the surface of the ground, but may have a burrow into which they can retreat. Beavers and muskrats are known for being semiaquatic, [1] but the rodent best-adapted for aquatic life is probably the earless water rat from New Guinea. [11] Rodents have also thrived in human-created environments such as agricultural and urban areas. [12]

Though some species are common pests for humans, rodents also play important ecological roles. [1] Some rodents are considered keystone species and ecosystem engineers in their respective habitats. In the Great Plains of North America, the burrowing activities of prairie dogs play important roles in soil aeration and nutrient redistribution, raising the organic content of the soil and increasing the absorption of water. They maintain these grassland habitats, [13] and some large herbivores such as bison and pronghorn prefer to graze near prairie dog colonies due to the increased nutritional quality of forage. [14]

Extirpation of prairie dogs can also contribute to regional and local biodiversity loss, increased seed depredation, and the establishment and spread of invasive shrubs. [13] Burrowing rodents may eat the fruiting bodies of fungi and spread spores through their feces, thereby allowing the fungi to disperse and form symbiotic relationships with the roots of plants (which usually cannot thrive without them). As such, these rodents may play a role in maintaining healthy forests. [15]

In many temperate regions, beavers play an essential hydrological role. When building their dams and lodges, beavers alter the paths of streams and rivers [16] and allow for the creation of extensive wetland habitats. One study found that engineering by beavers leads to a 33 percent increase in the number of herbaceous plant species in riparian areas. [17] Another study found that beavers increase wild salmon populations. [18]

Feeding Edit

Most rodents are herbivorous, feeding exclusively on plant material such as seeds, stems, leaves, flowers, and roots. Some are omnivorous and a few are predators. [2] The field vole is a typical herbivorous rodent and feeds on grasses, herbs, root tubers, moss, and other vegetation, and gnaws on bark during the winter. It occasionally eats invertebrates such as insect larvae. [19] The plains pocket gopher eats plant material found underground during tunneling, and also collects grasses, roots, and tubers in its cheek pouches and caches them in underground larder chambers. [20]

The Texas pocket gopher avoids emerging onto the surface to feed by seizing the roots of plants with its jaws and pulling them downwards into its burrow. It also practices coprophagy. [21] The African pouched rat forages on the surface, gathering anything that might be edible into its capacious cheek pouches until its face bulges out sideways. It then returns to its burrow to sort through the material it has gathered and eats the nutritious items. [22]

Agouti species are one of the few animal groups that can break open the large capsules of the Brazil nut fruit. Too many seeds are inside to be consumed in one meal, so the agouti carries some off and caches them. This helps dispersal of the seeds as any that the agouti fails to retrieve are distant from the parent tree when they germinate. Other nut-bearing trees tend to bear a glut of fruits in the autumn. These are too numerous to be eaten in one meal and squirrels gather and store the surplus in crevices and hollow trees. In desert regions, seeds are often available only for short periods. The kangaroo rat collects all it can find and stores them in larder chambers in its burrow. [22]

A strategy for dealing with seasonal plenty is to eat as much as possible and store the surplus nutrients as fat. Marmots do this, and may be 50% heavier in the autumn than in the spring. They rely on their fat reserves during their long winter hibernation. [22] Beavers feed on the leaves, buds, and inner bark of growing trees, as well as aquatic plants. They store food for winter use by felling small trees and leafy branches in the autumn and immersing them in their pond, sticking the ends into the mud to anchor them. Here, they can access their food supply underwater even when their pond is frozen over. [23]

Although rodents have been regarded traditionally as herbivores, most small rodents opportunistically include insects, worms, fungi, fish, or meat in their diets and a few have become specialized to rely on a diet of animal matter. A functional-morphological study of the rodent tooth system supports the idea that primitive rodents were omnivores rather than herbivores. Studies of the literature show that numerous members of the Sciuromorpha and Myomorpha, and a few members of the Hystricomorpha, have either included animal matter in their diets or been prepared to eat such food when offered it in captivity. Examination of the stomach contents of the North American white-footed mouse, normally considered to be herbivorous, showed 34% animal matter. [24]

More specialized carnivores include the shrewlike rats of the Philippines, which feed on insects and soft-bodied invertebrates, and the Australian water rat, which devours aquatic insects, fish, crustaceans, mussels, snails, frogs, birds' eggs, and water birds. [24] [25] The grasshopper mouse from dry regions of North America feeds on insects, scorpions, and other small mice, and only a small part of its diet is plant material. It has a chunky body with short legs and tail, but is agile and can easily overpower prey as large as itself. [26]

Social behavior Edit

Rodents exhibit a wide range of types of social behavior ranging from the mammalian caste system of the naked mole-rat, [27] the extensive "town" of the colonial prairie dog, [28] through family groups to the independent, solitary life of the edible dormouse. Adult dormice may have overlapping feeding ranges, but they live in individual nests and feed separately, coming together briefly in the breeding season to mate. The pocket gopher is also a solitary animal outside the breeding season, each individual digging a complex tunnel system and maintaining a territory. [29]

Larger rodents tend to live in family units where parents and their offspring live together until the young disperse. Beavers live in extended family units typically with a pair of adults, this year's kits, the previous year's offspring, and sometimes older young. [30] Brown rats usually live in small colonies with up to six females sharing a burrow and one male defending a territory around the burrow. At high population densities, this system breaks down and males show a hierarchical system of dominance with overlapping ranges. Female offspring remain in the colony while male young disperse. [31] The prairie vole is monogamous and forms a lifelong pair bond. Outside the breeding season, prairie voles live in close proximity with others in small colonies. A male is not aggressive towards other males until he has mated, after which time he defends a territory, a female, and a nest against other males. The pair huddles together, grooms one another, and shares nesting and pup-raising responsibilities. [32]

Among the most social of rodents are the ground squirrels, which typically form colonies based on female kinship, with males dispersing after weaning and becoming nomadic as adults. Cooperation in ground squirrels varies between species and typically includes making alarm calls, defending territories, sharing food, protecting nesting areas, and preventing infanticide. [33] The black-tailed prairie dog forms large towns that may cover many hectares. The burrows do not interconnect, but are excavated and occupied by territorial family groups known as coteries. A coterie often consists of an adult male, three or four adult females, several nonbreeding yearlings, and the current year's offspring. Individuals within coteries are friendly with each other, but hostile towards outsiders. [28]

Perhaps the most extreme examples of colonial behavior in rodents are the eusocial naked mole rat and Damaraland mole rat. The naked mole rat lives completely underground and can form colonies of up to 80 individuals. Only one female and up to three males in the colony reproduce, while the rest of the members are smaller and sterile, and function as workers. Some individuals are of intermediate size. They help with the rearing of the young and can take the place of a reproductive if one dies. [27] The Damaraland mole rat is characterized by having a single reproductively active male and female in a colony where the remaining animals are not truly sterile, but become fertile only if they establish a colony of their own. [34]

Communication Edit

Olfactory Edit

Rodents use scent marking in many social contexts including inter- and intra-species communication, the marking of trails and the establishment of territories. Their urine provides genetic information about individuals including the species, the sex and individual identity, and metabolic information on dominance, reproductive status and health. Compounds derived from the major histocompatibility complex (MHC) are bound to several urinary proteins. The odor of a predator depresses scent-marking behavior. [35]

Rodents are able to recognize close relatives by smell and this allows them to show nepotism (preferential behavior toward their kin) and also avoid inbreeding. This kin recognition is by olfactory cues from urine, feces and glandular secretions. The main assessment may involve the MHC, where the degree of relatedness of two individuals is correlated to the MHC genes they have in common. In non-kin communication, where more permanent odor markers are required, as at territorial borders, then non-volatile major urinary proteins (MUPs), which function as pheromone transporters, may also be used. MUPs may also signal individual identity, with each male house mouse (Mus musculus) excreting urine containing about a dozen genetically encoded MUPs. [36]

House mice deposit urine, which contains pheromones, for territorial marking, individual and group recognition, and social organization. [37] Territorial beavers and red squirrels investigate and become familiar with the scents of their neighbors and respond less aggressively to intrusions by them than to those made by non-territorial "floaters" or strangers. This is known as the "dear enemy effect". [38] [39]

Auditory Edit

Many rodent species, particularly those that are diurnal and social, have a wide range of alarm calls that are emitted when they perceive threats. There are both direct and indirect benefits of doing this. A potential predator may stop when it knows it has been detected, or an alarm call can allow conspecifics or related individuals to take evasive action. [40] Several species, for example prairie dogs, have complex anti-predator alarm call systems. These species may have different calls for different predators (e.g. aerial predators or ground-based predators) and each call contains information about the nature of the precise threat. [41] The urgency of the threat is also conveyed by the acoustic properties of the call. [42]

Social rodents have a wider range of vocalizations than do solitary species. Fifteen different call-types have been recognized in adult Kataba mole rats and four in juveniles. [43] Similarly, the common degu, another social, burrowing rodent, exhibits a wide array of communication methods and has an elaborate vocal repertoire comprising fifteen different categories of sound. [44] Ultrasonic calls play a part in social communication between dormice and are used when the individuals are out of sight of each other. [45]

House mice use both audible and ultrasonic calls in a variety of contexts. Audible vocalizations can often be heard during agonistic or aggressive encounters, whereas ultrasound is used in sexual communication and also by pups when they have fallen out of the nest. [37]

Laboratory rats (which are brown rats, Rattus norvegicus) emit short, high frequency, ultrasonic vocalizations during purportedly pleasurable experiences such as rough-and-tumble play, when anticipating routine doses of morphine, during mating, and when tickled. The vocalization, described as a distinct "chirping", has been likened to laughter, and is interpreted as an expectation of something rewarding. In clinical studies, the chirping is associated with positive emotional feelings, and social bonding occurs with the tickler, resulting in the rats becoming conditioned to seek the tickling. However, as the rats age, the tendency to chirp declines. Like most rat vocalizations, the chirping is at frequencies too high for humans to hear without special equipment, so bat detectors have been used for this purpose. [46]

Visual Edit

Rodents, like all placental mammals except primates, have just two types of light receptive cones in their retina, [47] a short wavelength "blue-UV" type and a middle wavelength "green" type. They are therefore classified as dichromats however, they are visually sensitive into the ultraviolet (UV) spectrum and therefore can see light that humans can not. The functions of this UV sensitivity are not always clear. In degus, for example, the belly reflects more UV light than the back. Therefore, when a degu stands up on its hind legs, which it does when alarmed, it exposes its belly to other degus and ultraviolet vision may serve a purpose in communicating the alarm. When it stands on all fours, its low UV-reflectance back could help make the degu less visible to predators. [48] Ultraviolet light is abundant during the day but not at night. There is a large increase in the ratio of ultraviolet to visible light in the morning and evening twilight hours. Many rodents are active during twilight hours (crepuscular activity), and UV-sensitivity would be advantageous at these times. Ultraviolet reflectivity is of dubious value for nocturnal rodents. [49]

The urine of many rodents (e.g. voles, degus, mice, rats) strongly reflects UV light and this may be used in communication by leaving visible as well as olfactory markings. [50] However, the amount of UV that is reflected decreases with time, which in some circumstances can be disadvantageous the common kestrel can distinguish between old and fresh rodent trails and has greater success hunting over more recently marked routes. [51]

Tactile Edit

Vibrations can provide cues to conspecifics about specific behaviors being performed, predator warning and avoidance, herd or group maintenance, and courtship. The Middle East blind mole rat was the first mammal for which seismic communication was documented. These fossorial rodents bang their head against the walls of their tunnels. This behavior was initially interpreted as part of their tunnel building behavior, but it was eventually realized that they generate temporally patterned seismic signals for long-distance communication with neighboring mole rats. [52]

Footdrumming is used widely as a predator warning or defensive action. It is used primarily by fossorial or semi-fossorial rodents. [53] The banner-tailed kangaroo rat produces several complex footdrumming patterns in a number of different contexts, one of which is when it encounters a snake. The footdrumming may alert nearby offspring but most likely conveys that the rat is too alert for a successful attack, thus preventing the snake's predatory pursuit. [52] [54] Several studies have indicated intentional use of ground vibrations as a means of intra-specific communication during courtship among the Cape mole rat. [55] Footdrumming has been reported to be involved in male-male competition the dominant male indicates its resource holding potential by drumming, thus minimizing physical contact with potential rivals. [52]

Mating strategies Edit

Some species of rodent are monogamous, with an adult male and female forming a lasting pair bond. Monogamy can come in two forms obligate and facultative. In obligate monogamy, both parents care for the offspring and play an important part in their survival. This occurs in species such as California mice, oldfield mice, Malagasy giant rats and beavers. In these species, males usually mate only with their partners. In addition to increased care for young, obligate monogamy can also be beneficial to the adult male as it decreases the chances of never finding a mate or mating with an infertile female. In facultative monogamy, the males do not provide direct parental care and stay with one female because they cannot access others due to being spatially dispersed. Prairie voles appear to be an example of this form of monogamy, with males guarding and defending females within their vicinity. [56]

In polygynous species, males will try to monopolize and mate with multiple females. As with monogamy, polygyny in rodents can come in two forms defense and non-defense. Defense polygyny involves males controlling territories that contain resources that attract females. This occurs in ground squirrels like yellow-bellied marmots, California ground squirrels, Columbian ground squirrels and Richardson's ground squirrels. Males with territories are known as "resident" males and the females that live within the territories are known as "resident" females. In the case of marmots, resident males do not appear to ever lose their territories and always win encounters with invading males. Some species are also known to directly defend their resident females and the ensuing fights can lead to severe wounding. In species with non-defense polygyny, males are not territorial and wander widely in search of females to monopolize. These males establish dominance hierarchies, with the high-ranking males having access to the most females. This occurs in species like Belding's ground squirrels and some tree squirrel species. [56]

Promiscuity, in which both males and females mate with multiple partners, also occurs in rodents. In species such as the white-footed mouse, females give birth to litters with multiple paternities. Promiscuity leads to increased sperm competition and males tend to have larger testicles. In the Cape ground squirrel, the male's testes can be 20 percent of its head-body length. [56] Several rodent species have flexible mating systems that can vary between monogamy, polygyny and promiscuity. [56]

Female rodents play an active role in choosing their mates. Factors that contribute to female preference may include the size, dominance and spatial ability of the male. [57] In the eusocial naked mole rats, a single female monopolizes mating from at least three males. [27]

In most rodent species, such as brown rats and house mice, ovulation occurs on a regular cycle while in others, such as voles, it is induced by mating. During copulation, males of some rodent species deposit a mating plug in the female's genital opening, both to prevent sperm leakage and to protect against other males inseminating the female. Females can remove the plug and may do so either immediately or after several hours. [57]

Birth and parenting Edit

Rodents may be born either altricial (blind, hairless and relatively underdeveloped) or precocial (mostly furred, eyes open and fairly developed) depending on the species. The altricial state is typical for squirrels and mice, while the precocial state usually occurs in species like guinea pigs and porcupines. Females with altricial young typically build elaborate nests before they give birth and maintain them until their offspring are weaned. The female gives birth sitting or lying down and the young emerge in the direction she is facing. The newborns first venture out of the nest a few days after they have opened their eyes and initially keep returning regularly. As they get older and more developed, they visit the nest less often and leave permanently when weaned. [58]

In precocial species, the mothers invest little in nest building and some do not build nests at all. The female gives birth standing and the young emerge behind her. Mothers of these species maintain contact with their highly mobile young with maternal contact calls. Though relatively independent and weaned within days, precocial young may continue to nurse and be groomed by their mothers. Rodent litter sizes also vary and females with smaller litters spend more time in the nest than those with larger litters. [58]

Mother rodents provide both direct parental care, such as nursing, grooming, retrieving and huddling, and indirect parenting, such as food caching, nest building and protection to their offspring. [58] In many social species, young may be cared for by individuals other than their parents, a practice known as alloparenting or cooperative breeding. This is known to occur in black-tailed prairie dogs and Belding's ground squirrels, where mothers have communal nests and nurse unrelated young along with their own. There is some question as to whether these mothers can distinguish which young are theirs. In the Patagonian mara, young are also placed in communal warrens, but mothers do not permit youngsters other than their own to nurse. [59]

Infanticide exists in numerous rodent species and may be practiced by adult conspecifics of either sex. Several reasons have been proposed for this behavior, including nutritional stress, resource competition, avoiding misdirecting parental care and, in the case of males, attempting to make the mother sexually receptive. The latter reason is well supported in primates and lions but less so in rodents. [60] Infanticide appears to be widespread in black-tailed prairie dogs, including infanticide from invading males and immigrant females, as well as occasional cannibalism of an individual's own offspring. [61] To protect against infanticide from other adults, female rodents may employ avoidance or direct aggression against potential perpetrators, multiple mating, territoriality or early termination of pregnancy. [60] Feticide can also occur among rodents in Alpine marmots, dominant females tend to suppress the reproduction of subordinates by being antagonistic towards them while they are pregnant. The resulting stress causes the fetuses to abort. [62]

Intelligence Edit

Rodents have advanced cognitive abilities. They can quickly learn to avoid poisoned baits, which makes them difficult pests to deal with. [1] Guinea pigs can learn and remember complex pathways to food. [63] Squirrels and kangaroo rats are able to locate caches of food by spatial memory, rather than just by smell. [64] [65]

Because laboratory mice (house mice) and rats (brown rats) are widely used as scientific models to further our understanding of biology, a great deal has come to be known about their cognitive capacities. Brown rats exhibit cognitive bias, where information processing is biased by whether they are in a positive or negative affective state. [66] For example, laboratory rats trained to respond to a specific tone by pressing a lever to receive a reward, and to press another lever in response to a different tone so as to avoid receiving an electric shock, are more likely to respond to an intermediate tone by choosing the reward lever if they have just been tickled (something they enjoy), indicating "a link between the directly measured positive affective state and decision making under uncertainty in an animal model." [67]

Laboratory (brown) rats may have the capacity for metacognition—to consider their own learning and then make decisions based on what they know, or do not know, as indicated by choices they make apparently trading off difficulty of tasks and expected rewards, making them the first animals other than primates known to have this capacity, [68] [69] but these findings are disputed, since the rats may have been following simple operant conditioning principles, [70] or a behavioral economic model. [71] Brown rats use social learning in a wide range of situations, but perhaps especially so in acquiring food preferences. [72] [73]

Evolutionary history Edit

Dentition is the key feature by which fossil rodents are recognized and the earliest record of such mammals comes from the Paleocene, shortly after the extinction of the non-avian dinosaurs some 66 million years ago. These fossils are found in Laurasia, [74] the supercontinent composed of modern-day North America, Europe, and Asia. The divergence of Glires, a clade consisting of rodents and lagomorphs (rabbits, hares and pikas), from other placental mammals occurred within a few million years after the Cretaceous-Tertiary boundary rodents and lagomorphs then radiated during the Cenozoic. [75] Some molecular clock data suggest modern rodents (members of the order Rodentia) had appeared by the late Cretaceous, although other molecular divergence estimations are in agreement with the fossil record. [76] [77]

Rodents are thought to have evolved in Asia, where local multituberculate faunas were severely affected by the Cretaceous–Paleogene extinction event and never fully recovered, unlike their North American and European relatives. In the resulting ecological vacuum, rodents and other Glires were able to evolve and diversify, taking the niches left by extinct multituberculates. The correlation between the spread of rodents and the demise of multituberculates is a controversial topic, not fully resolved. American and European multituberculate assemblages do decline in diversity in correlation with the introduction of rodents in these areas, but the remaining Asian multituberculates co-existed with rodents with no observable replacement taking place, and ultimately both clades co-existed for at least 15 million years. [78]

The history of the colonization of the world's continents by rodents is complex. The movements of the large superfamily Muroidea (including hamsters, gerbils, true mice and rats) may have involved up to seven colonizations of Africa, five of North America, four of Southeast Asia, two of South America and up to ten of Eurasia. [79]

During the Eocene, rodents began to diversify. Beavers appeared in Eurasia in the late Eocene before spreading to North America in the late Miocene. [81] Late in the Eocene, hystricognaths invaded Africa, most probably having originated in Asia at least 39.5 million years ago. [82] From Africa, fossil evidence shows that some hystricognaths (caviomorphs) colonized South America, which was an isolated continent at the time, evidently making use of ocean currents to cross the Atlantic on floating debris. [83] Caviomorphs had arrived in South America by 41 million years ago (implying a date at least as early as this for hystricognaths in Africa), [82] and had reached the Greater Antilles by the early Oligocene, suggesting that they must have dispersed rapidly across South America. [84]

Nesomyid rodents are thought to have rafted from Africa to Madagascar 20–24 million years ago. [85] All 27 species of native Malagasy rodents appear to be descendants of a single colonization event.

By 20 million years ago, fossils recognizably belonging to the current families such as Muridae had emerged. [74] By the Miocene, when Africa had collided with Asia, African rodents such as the porcupine began to spread into Eurasia. [86] Some fossil species were very large in comparison to modern rodents and included the giant beaver, Castoroides ohioensis, which grew to a length of 2.5 m (8 ft 2 in) and weight of 100 kg (220 lb). [87] The largest known rodent was Josephoartigasia monesi, a pacarana with an estimated body length of 3 m (10 ft). [88]

The first rodents arrived in Australia via Indonesia around 5 million years ago. Although marsupials are the most prominent mammals in Australia, many rodents, all belonging to the subfamily Murinae, are among the continent's mammal species. [89] There are about fifty species of 'old endemics', the first wave of rodents to colonize the country in the Miocene and early Pliocene, and eight true rat (Rattus) species of 'new endemics', arriving in a subsequent wave in the late Pliocene or early Pleistocene. The earliest fossil rodents in Australia have a maximum age of 4.5 million years, [90] and molecular data is consistent with the colonization of New Guinea from the west during the late Miocene or early Pliocene followed by rapid diversification. A further wave of adaptive radiation occurred after one or more colonizations of Australia some 2 to 3 million years later. [91]

Rodents participated in the Great American Interchange that resulted from the joining of the Americas by formation of the Isthmus of Panama, around 3 million years ago in the Piacenzian age. [92] In this exchange, a small number of species such as the New World porcupines (Erethizontidae) headed north. [74] However, the main southward invasion of sigmodontines preceded formation of the land bridge by at least several million years, probably occurring via rafting. [93] [94] [95] Sigmodontines diversified explosively once in South America, although some degree of diversification may have already occurred in Central America before the colonization. [94] [95]

Standard classification Edit

The use of the order name "Rodentia" is attributed to the English traveler and naturalist Thomas Edward Bowdich (1821). [96] The Modern Latin word Rodentia is derived from rodens, present participle of rodere – "to gnaw", "eat away". [97] The hares, rabbits and pikas (order Lagomorpha) have continuously growing incisors, as do rodents, and were at one time included in the order. However, they have an additional pair of incisors in the upper jaw and the two orders have quite separate evolutionary histories. [98] The phylogeny of the rodents places them in the clades Glires, Euarchontoglires and Boreoeutheria. The cladogram below shows the inner and outer relations of Rodentia based on a 2012 attempt by Wu et al. to align the molecular clock with paleontological data: [99]

Atherurus (brush-tailed porcupines)

Erethizon (North American porcupines)

Glaucomys (New World flying squirrels)

The living rodent families based on the study done by Fabre et al. 2012. [100]

The order Rodentia may be divided into suborders, infraorders, superfamilies and families. There is a great deal of parallelism and convergence among rodents caused by the fact that they have tended to evolve to fill largely similar niches. This parallel evolution includes not only the structure of the teeth, but also the infraorbital region of the skull (below the eye socket) and makes classification difficult as similar traits may not be due to common ancestry. [101] [102] Brandt (1855) was the first to propose dividing Rodentia into three suborders, Sciuromorpha, Hystricomorpha and Myomorpha, based on the development of certain muscles in the jaw and this system was widely accepted. Schlosser (1884) performed a comprehensive review of rodent fossils, mainly using the cheek teeth, and found that they fitted into the classical system, but Tullborg (1899) proposed just two sub-orders, Sciurognathi and Hystricognathi. These were based on the degree of inflection of the lower jaw and were to be further subdivided into Sciuromorpha, Myomorpha, Hystricomorpha and Bathyergomorpha. Matthew (1910) created a phylogenetic tree of New World rodents but did not include the more problematic Old World species. Further attempts at classification continued without agreement, with some authors adopting the classical three suborder system and others Tullborg's two suborders. [101]

These disagreements remain unresolved, nor have molecular studies fully resolved the situation though they have confirmed the monophyly of the group and that the clade has descended from a common Paleocene ancestor. Carleton and Musser (2005) in Mammal Species of the World have provisionally adopted a five suborder system: Sciuromorpha, Castorimorpha, Myomorpha, Anomaluromorpha, and Hystricomorpha. These include 33 families, 481 genera and 2277 species. [103] [104]

Order Rodentia (from Latin, rodere, to gnaw)

  • Suborder Anomaluromorpha
    • Family Anomaluridae: scaly-tailed squirrels
    • Family Pedetidae: springhares
    • Superfamily Castoroidea
      • Family Castoridae: beavers
      • Family Geomyidae: pocket gophers (true gophers)
      • Family Heteromyidae: kangaroo rats, kangaroo mice
      • Infraorder Ctenodactylomorphi
        • Family Ctenodactylidae: gundis
        • Family Bathyergidae: African mole rats
        • Family Hystricidae: Old World porcupines
        • Family Petromuridae: dassie rat
        • Family Thryonomyidae: cane rats
        • Parvorder Caviomorpha
          • Family †Heptaxodontidae: giant hutias
          • Family Abrocomidae: chinchilla rats
          • Family Capromyidae: hutias
          • Family Caviidae: cavies, including Guinea pigs and the capybara
          • Family Chinchillidae: chinchillas, viscachas
          • Family Ctenomyidae: tuco-tucos
          • Family Dasyproctidae: agoutis
          • Family Cuniculidae: pacas
          • Family Dinomyidae: pacaranas
          • Family Echimyidae: spiny rats
          • Family Erethizontidae: New World porcupines
          • Family Myocastoridae: coypu (nutria)
          • Family Octodontidae: octodonts
          • Family Diatomyidae: Laotian rock rat
          • Superfamily Dipodoidea
            • Family Dipodidae: jerboas and jumping mice
            • Family Calomyscidae: mouse-like hamsters
            • Family Cricetidae: hamsters, New World rats and mice, muskrats, voles, lemmings
            • Family Muridae: true mice and rats, gerbils, spiny mice, crested rat
            • Family Nesomyidae: climbing mice, rock mice, white-tailed rat, Malagasy rats and mice
            • Family Platacanthomyidae: spiny dormice
            • Family Spalacidae: mole rats, bamboo rats, zokors
            • Family Aplodontiidae: mountain beaver
            • Family Gliridae (also Myoxidae, Muscardinidae): dormice
            • Family Sciuridae: squirrels, including chipmunks, prairie dogs, marmots

            Conservation Edit

            While rodents are not the most seriously threatened order of mammals, there are 168 species in 126 genera that are said to warrant conservation attention [105] in the face of limited appreciation by the public. Since 76 percent of rodent genera contain only one species, much phylogenetic diversity could be lost with a comparatively small number of extinctions. In the absence of more detailed knowledge of species at risk and accurate taxonomy, conservation must be based mainly on higher taxa (such as families rather than species) and geographical hot spots. [105] Several species of rice rat have become extinct since the 19th century, probably through habitat loss and the introduction of alien species. [106] In Colombia, the brown hairy dwarf porcupine was recorded from only two mountain localities in the 1920s, while the red crested soft-furred spiny rat is known only from its type locality on the Caribbean coast, so these species are considered vulnerable. [107] The IUCN Species Survival Commission writes "We can safely conclude that many South American rodents are seriously threatened, mainly by environmental disturbance and intensive hunting". [108]

            The "three now cosmopolitan commensal rodent pest species" [109] (the brown rat, the black rat and the house mouse) have been dispersed in association with humans, partly on sailing ships in the Age of Exploration, and with a fourth species in the Pacific, the Polynesian rat (Rattus exulans), have severely damaged island biotas around the world. For example, when the black rat reached Lord Howe Island in 1918, over 40 percent of the terrestrial bird species of the island, including the Lord Howe fantail, [110] became extinct within ten years. Similar destruction has been seen on Midway Island (1943) and Big South Cape Island (1962). Conservation projects can with careful planning completely eradicate these pest rodents from islands using an anticoagulant rodenticide such as brodifacoum. [109] This approach has been successful on the island of Lundy in the United Kingdom, where the eradication of an estimated 40,000 brown rats is giving populations of Manx shearwater and Atlantic puffin a chance to recover from near-extinction. [111] [112]

            Rodents have also been susceptible to climate change, especially species living on low-lying islands. The Bramble Cay melomys, which lived in the northernmost point of land of Australia, was the first mammal species to be declared extinct as a consequence of human-caused climate change. [113]

            Exploitation Edit

            Humanity has long used animal skins for clothing, as the leather is durable and the fur provides extra insulation. [2] The native people of North America made much use of beaver pelts, tanning and sewing them together to make robes. Europeans appreciated the quality of these and the North American fur trade developed and became of prime importance to early settlers. In Europe, the soft underfur known as "beaver wool" was found to be ideal for felting and was made into beaver hats and trimming for clothing. [114] [115] Later, the coypu took over as a cheaper source of fur for felting and was farmed extensively in America and Europe however, fashions changed, new materials became available and this area of the animal fur industry declined. [116] The chinchilla has a soft and silky coat and the demand for its fur was so high that it was nearly wiped out in the wild before farming took over as the main source of pelts. [116] The quills and guardhairs of porcupines are used for traditional decorative clothing. For example, their guardhairs are used in the creation of the Native American "porky roach" headdress. The main quills may be dyed, and then applied in combination with thread to embellish leather accessories such as knife sheaths and leather bags. Lakota women would harvest the quills for quillwork by throwing a blanket over a porcupine and retrieving the quills it left stuck in the blanket. [117]

            Consumption Edit

            At least 89 species of rodent, mostly Hystricomorpha such as guinea pigs, agoutis and capybaras, are eaten by humans in 1985, there were at least 42 different societies in which people eat rats. [118] Guinea pigs were first raised for food around 2500 B.C. and by 1500 B.C. had become the main source of meat for the Inca Empire. Dormice were raised by the Romans in special pots called "gliraria", or in large outdoor enclosures, where they were fattened on walnuts, chestnuts, and acorns. The dormice were also caught from the wild in autumn when they were fattest, and either roasted and dipped into honey or baked while stuffed with a mixture of pork, pine nuts, and other flavorings. Researchers found that in Amazonia, where large mammals were scarce, pacas and common agoutis accounted for around 40 percent of the annual game taken by the indigenous people, but in forested areas where larger mammals were abundant, these rodents constituted only about 3 percent of the take. [118]

            Guinea pigs are used in the cuisine of Cuzco, Peru, in dishes such as cuy al horno, baked guinea pig. [2] [119] The traditional Andean stove, known as a qoncha or a fogón, is made from mud and clay reinforced with straw and hair from animals such as guinea pigs. [120] In Peru, there are at any time 20 million domestic guinea pigs, which annually produce 64 million edible carcasses. This animal is an excellent food source since the flesh is 19% protein. [118] In the United States, mostly squirrels, but also muskrats, porcupines, and groundhogs are eaten by humans. The Navajo people ate prairie dog baked in mud, while the Paiute ate gophers, squirrels, and rats. [118]

            Animal testing Edit

            Rodents are used widely as model organisms in animal testing. [2] [121] Albino mutant rats were first used for research in 1828 and later became the first animal domesticated for purely scientific purposes. [122] Nowadays, the house mouse is the most commonly used laboratory rodent, and in 1979 it was estimated that fifty million were used annually worldwide. They are favored because of their small size, fertility, short gestation period and ease of handling and because they are susceptible to many of the conditions and infections that afflict humans. They are used in research into genetics, developmental biology, cell biology, oncology and immunology. [123] Guinea pigs were popular laboratory animals until the late 20th century about 2.5 million guinea pigs were used annually in the United States for research in the 1960s, [124] but that total decreased to about 375,000 by the mid-1990s. [125] In 2007, they constituted about 2% of all laboratory animals. [124] Guinea pigs played a major role in the establishment of germ theory in the late 19th century, through the experiments of Louis Pasteur, Émile Roux, and Robert Koch. [126] They have been launched into orbital space flight several times—first by the USSR on the Sputnik 9 biosatellite of March 9, 1961, with a successful recovery. [127] The naked mole rat is the only known mammal that is poikilothermic it is used in studies on thermoregulation. It is also unusual in not producing the neurotransmitter substance P, a fact which researchers find useful in studies on pain. [128]

            Rodents have sensitive olfactory abilities, which have been used by humans to detect odors or chemicals of interest. [129] The Gambian pouched rat is able to detect tuberculosis bacilli with a sensitivity of up to 86.6%, and specificity (detecting the absence of the bacilli) of over 93% the same species has been trained to detect land mines. [130] [131] Rats have been studied for possible use in hazardous situations such as in disaster zones. They can be trained to respond to commands, which may be given remotely, and even persuaded to venture into brightly lit areas, which rats usually avoid. [132] [133] [134]

            As pets Edit

            Rodents including guinea pigs, [135] mice, rats, hamsters, gerbils, chinchillas, degus and chipmunks make convenient pets able to live in small spaces, each species with its own qualities. [136] Most are normally kept in cages of suitable sizes and have varied requirements for space and social interaction. If handled from a young age, they are usually docile and do not bite. Guinea pigs have a long lifespan and need a large cage. [63] Rats also need plenty of space and can become very tame, can learn tricks and seem to enjoy human companionship. Mice are short-lived but take up very little space. Hamsters are solitary but tend to be nocturnal. They have interesting behaviors, but unless handled regularly they may be defensive. Gerbils are not usually aggressive, rarely bite and are sociable animals that enjoy the company of humans and their own kind. [137]

            As pests and disease vectors Edit

            Some rodent species are serious agricultural pests, eating large quantities of food stored by humans. [138] For example, in 2003, the amount of rice lost to mice and rats in Asia was estimated to be enough to feed 200 million people. Most of the damage worldwide is caused by a relatively small number of species, chiefly rats and mice. [139] In Indonesia and Tanzania, rodents reduce crop yields by around fifteen percent, while in some instances in South America losses have reached ninety percent. Across Africa, rodents including Mastomys and Arvicanthis damage cereals, groundnuts, vegetables and cacao. In Asia, rats, mice and species such as Microtus brandti, Meriones unguiculatus and Eospalax baileyi damage crops of rice, sorghum, tubers, vegetables and nuts. In Europe, as well as rats and mice, species of Apodemus, Microtus and in occasional outbreaks Arvicola terrestris cause damage to orchards, vegetables and pasture as well as cereals. In South America, a wider range of rodent species, such as Holochilus, Akodon, Calomys, Oligoryzomys, Phyllotis, Sigmodon and Zygodontomys, damage many crops including sugar cane, fruits, vegetables, and tubers. [139]

            Rodents are also significant vectors of disease. [140] The black rat, with the fleas that it carries, plays a primary role in spreading the bacterium Yersinia pestis responsible for bubonic plague, [141] and carries the organisms responsible for typhus, Weil's disease, toxoplasmosis and trichinosis. [140] A number of rodents carry hantaviruses, including the Puumala, Dobrava and Saaremaa viruses, which can infect humans. [142] Rodents also help to transmit diseases including babesiosis, cutaneous leishmaniasis, human granulocytic anaplasmosis, Lyme disease, Omsk hemorrhagic fever, Powassan virus, rickettsialpox, relapsing fever, Rocky Mountain spotted fever, and West Nile virus. [143]

            Because rodents are a nuisance and endanger public health, human societies often attempt to control them. Traditionally, this involved poisoning and trapping, methods that were not always safe or effective. More recently, integrated pest management attempts to improve control with a combination of surveys to determine the size and distribution of the pest population, the establishment of tolerance limits (levels of pest activity at which to intervene), interventions, and evaluation of effectiveness based on repeated surveys. Interventions may include education, making and applying laws and regulations, modifying the habitat, changing farming practices, and biological control using pathogens or predators, as well as poisoning and trapping. [144] The use of pathogens such as Salmonella has the drawback that they can infect man and domestic animals, and rodents often become resistant. The use of predators including ferrets, mongooses and monitor lizards has been found unsatisfactory. Domestic and feral cats are able to control rodents effectively, provided the rodent population is not too large. [145] In the UK, two species in particular, the house mouse and the brown rat, are actively controlled to limit damage in growing crops, loss and contamination of stored crops and structural damage to facilities, as well as to comply with the law. [146]


            Native Australian Animals

            1. Australian Giant Cuttlefish

            A cuttlefish is a Cephalopod, like squid and octopuses. The Australian Giant Cuttlefish is the largest of the species, and can weigh as much as 10kg! It can be found along the southern coast from Shark Bay in WA to Brisbane in Queensland.

            By Jacob Bridgeman – Own work , CC BY-SA 3.0, via Wikimedia Commons

            2. Australian Pelican

            The Australian pelican is one of the many species of pelican. It can be found in the inland and coastal waters of Australia, occupying habitats such as rivers, lakes and swamps. The main features of a pelican are its long beak and massive wingspan. The Australian pelican can have a wingspan up to 2 and a half metres!

            The Australian pelican is fairly common

            3. Bandicoot

            There are 20 species of bandicoot. They’re endemic to Australia and they’re marsupials which are nocturnal and also omnivores (they eat both meat and plants). They’re also pretty cute.

            By JJ Harrison ([email protected]) – Own work , CC BY-SA 3.0, via Wikimedia Commons

            4. Bilby

            There were 2 species of bilby. The lesser bilby is sadly extinct but the greater bilby can still be found in Australia, although it is endangered. Also known as a rabbit bandicoot, because it’s very similar to the bandicoot but with very long ears, the bilby is native to Australia.

            By Bernard DUPONT from FRANCE (Greater Bilby (Macrotis lagotis)) [CC BY-SA 2.0], via Wikimedia Commons

            5. Bottlenose dolphin

            Found in tropical or temperate waters all over the world. If you go near or on the ocean in Australia you’ll be unlucky not to spot bottlenose dolphins at some point during your trip. I highly recommend going on a sea kayaking trip in Byron Bay for a great opportunity to spot dolphins up close.

            Go Sea Kayak

            6. Brolga

            The Brolga used to be known as the “Native Australian Crane”. As well as being the largest flying bird in Australia it’s also known for it’s mating dance. You can find Brolga’s in many parts of tropical Australia, especially Queensland. In fact it’s the official bird emblem of Queensland.

            7. Camel

            Camels are not native Australian animals and hopefully that isn’t too much of a shock to you! They’re worth a mention simply because there are so many wild camels in the country (around 1.2 million of them!) especially in the Outback. They were imported to help with transportation and construction back in the 19th century but are now feral. There are so many camels that they’re exported to the Middle East.

            By Jjron – Own work , CC BY-SA 3.0, via Wikimedia Commons

            8. Cane toad

            Also not native to Australia, the cane toad was introduced to Australia in an attempt to control the beetle populations which were destroying sugar cane crops (a major crop for Australia’s economy). The cane toad spread rapidly through Australia and is also spreading disease. You’ll mainly see these large toads dead on the road or being harassed in quite a few pubs during cane toad races.

            By Joydeb halder (Own work) [CC BY-SA 4.0], via Wikimedia Commons

            9. Cassowary

            A terrifying looking bird in many ways but also quite beautiful because of the colours on its head and neck. You can find the cassowary in Northern Queensland although they’re relatively shy so you might not spot one. Just be aware that even though they’re shy if you do come across one they’re dangerous!

            Cassowary – pixabay

            10. Cockatoo

            Cockatoos are fairly common in Australia, they’re intelligent birds that can be very loud! If you visit the Arts Factory Lodge book yourself on a free BushTucker Walk to meet Cockatoo Paul and Mr Pickles.

            Cockatoo Paul and Mr Pickles – abc.net.au

            11. Crocodile

            The saltie! Saltwater crocodiles are pretty common in waterways in Australia, especially in the north. If you see warning signs telling you to stay out of the water then stay out of the water! Although salties are pretty massive they manage to hide quite well in the water and they’re quick so you won’t fare well against one. Of all the Aussie animals listed in this article this one might be the most terrifying!

            By Bernard DUPONT from FRANCE (Saltwater Crocodile (Crocodylus porosus)) [CC BY-SA 2.0], via Wikimedia Commons

            12. Dingo

            Well you’ll have heard of the dingo which, although endangered, can be easily seen on Fraser Island. Dingoes are protected on Fraser Island so if you visit (and you really must) please adhere to all the rules for keeping yourself and the dingoes safe from harm.

            Dingo on Fraser Island at night

            13. Dugong

            Dugongs are similar to manatees in appearance and the only marine mammal which is a herbivore (eats only plants). Dugongs are threatened with extinction so if you do see one you’re very lucky. You’re more likely to see them in Shark Bay in WA or in Queensland. Dugongs are also known as sea cows or the “Lady of The Sea” and are thought to be the inspiration behind tales of mermaids.

            By Gejuni – Own work , CC BY-SA 3.0 de, via Wikimedia Commons

            14. Echidna

            Echidna’s really are one of the oddest animals of Australia. One of only 2 egg laying mammals that exist in the whole world, it looks a lot like a porcupine but is more closely related to a platypus. After laying a single egg 22 days after mating, the female echidna deposits the egg directly into her pouch where it remains for up to 2 months. Baby echidnas are called puggles which is just the best name for a baby animal! Male echidnas have a four headed penis! Moving on…

            I, KeresH [GFDL, CC-BY-SA-3.0 or CC BY-SA 2.5-2.0-1.0], via Wikimedia Commons

            15. Emu

            Large, terrifying up close and flightless, emu’s are not one of the most popular animals of Australia. Surprising then that they appear on the Australian Coat of Arms alongside the kangaroo. Possibly even more surprising is that they were allowed to remain on the Coat of Arms after they beat the Australian army in the unbelievable, but very real, Great Emu War. Emu’s are endemic to Australia and are it’s largest bird.

            By Vcarceler (Own work) [CC BY-SA 3.0], via Wikimedia Commons

            16. Fairy Penguin

            Even 10 years after first seeing penguins in Australia with my very own eyes it still seems strange to me that what is thought of as a very hot country would have an animal that is most well known for living in icy climates. But there we go. Fairy penguins, which are incredibly cute, are quite commonly seen in Australia, most famously on Phillip Island where you can witness for yourself their parade up the beach. I highly recommend doing a tour to see them but please DON’T take pictures using your flash!

            Penguin Parade – Bunyip Tours

            17. Flying Fox

            Just to be confusing this is a bat not a fox. The grey headed flying fox is a mega-bat endemic to Australia. It’s mostly found in the south eastern parts of the country. The little red flying fox is also a native mega-bat but living in north and eastern areas. It’s the smallest of Australia’s flying foxes. Also in the north eastern parts of the country you’ll find the spectacled flying fox (or spectacled fruit bat). Finally you may also see a black flying fox on your travels. A mega bat is larger than usual bats, they’re also known as fruit bats and many do not use echo-location.

            Photo by shellac – license

            18. Frill Necked Lizard

            Frill necked lizards are fairly hard to spot as their colours help them to stay camouflaged, except when they display their colourful frills of course. These lizards are relatively large but harmless and if you keep your eyes open you might spot one in the northern territories.

            By Miklos Schiberna (Own work) [Public domain], via Wikimedia Commons

            19. Fur Seal

            The Australian fur seal is the largest of all fur seals and the 4th rarest species of seal in the world, so they’re a protected animal in Australia. Fur seals tend to be found in the south of the country with Seal Rock on Phillip Island being a good place to look for them!

            By JJ Harrison ([email protected]) – Own work , CC BY-SA 3.0, via Wikimedia Commons

            20. Galah

            A galah is not just an Australian slang word for a stupid person, it’s also an Australian cockatoo with a reputation for not being too bright.

            Photo by patrickkavanagh – license

            21. Giant Clam

            If you plan on doing some underwater exploration of the Great Barrier Reef during your trip to Australia then you’re quite likely to come across a giant clam or two. Giant clams can weigh up to a whopping 200kg and can live for 100 years. They start their lives male but become hermaphrodites (can produce both sperm and eggs).

            Giant Clams on the Great Barrier Reef

            22. Goanna

            A Goanna is a type of monitor lizard which varies in size from just 20cm long to 2 metres! Depending on what source you use there are thought to be either 20 or 30 species of monitor lizard, 15 or 25 of which can be found in Australia.

            By Thomas Schoch [CC BY-SA 2.5], via Wikimedia Commons

            23. Great White Shark

            The only reason I didn’t list this as the most terrifying on this list of Australian animals is because Great Whites have had a bit of a raw deal. Yes, they’re scary and yes they can be deadly but the majority of the time they’re not going to bother you. The Jaws films have a lot to answer for with regard to this animals reputation. They can grow up to 6 metres long and are scary looking but my advice? Don’t go in the water during a sharks dinner time!

            By Hermanus Backpackers (Great White Shark Cage Diving) [CC BY 2.0], via Wikimedia Commons

            24. Humphead Wrasse

            If you’ve visited the Great Barrier Reef you have more than likely seen a Humphead Wrasse, also known as a Maori Wrasse or Napoleon Wrasse. It’s an endangered species due to overfishing, but if you see one, they’re very friendly, and quite big. Go on a snorkel or scuba diving tour and you will be introduced to Wally the Wrasse.

            The Humphead or Napoleon Wrasse

            25. Ibis (Australian White)

            You’ll see this fairly large and strange looking bird all over the place. Sadly they have a bad reputation and are known as bin chickens or tip turkeys due to their scavenging behaviour. This is due to the fact that it can be a lot easier for them to feed from rubbish left around by humans than in their normal wetland environment.

            By Thomas Quine (Australian White Ibis) [CC BY 2.0], via Wikimedia Commons

            26. Kangaroo

            Alongside the koala, kangaroos are probably the most well known of all the animals of Australia. The red kangaroo is the largest while the grey kangaroo is the one you’re likely to see most often. Appearing on the Coat of Arms beside the emu, the kangaroo is also a popular Aussie food.

            Kangaroos can be seen all over Australia

            27. Koala

            Looks like a teddy bear but is NOT a bear, don’t even think of referring to them as koala bears near Australians!! Koala’s are fairly common in coastal areas in the south and east of the country but their habitats are being threatened by humans. Koala’s in the north tend to be smaller than their southern counterparts which can be up to twice as heavy. Is this the cutest Australian animal in this list? No, but it’s close… keep reading for the cutest of all the native Australian animals (in my opinion anyway).

            Koala on Magnetic Island

            28. Kookaburra

            Kookaburra’s are part of the Kingfisher family and it’s largest member. The native Australian kookaburra’s are probably most well known for their laugh. Their heads are also quite large in comparison to the rest of their bodies.

            29. Lyre Bird

            The Lyre Bird could also be called a liar bird because it imitates other birds and other sounds so well. I’ll let the incredible Sir David Attenborough tell you more about them!

            30. Magpie

            Magpies can be found all over the place so it might seem strange to mention them here, but the Australian magpies are a bit different to the ones you’ll find in the UK for example. Not only are their colours back to front they are known to be quite vicious. However don’t believe everything you hear about them as magpies are quite intelligent and are even capable of recognising faces. This is not such a great attribute if the magpie decides he doesn’t like you though!

            By Toby Hudson (Own work) [CC BY-SA 3.0], via Wikimedia Commons

            31. Numbat

            I don’t know why more people haven’t heard of the numbat. They’re native Australian animals (to Western Australia), marsupials and really quite odd looking creatures, although very cute. The numbat resembles an anteater and is in fact known as the banded anteater. They’re endangered due to introduced predators such as cats and foxes so they’re not commonly seen.

            Martin Pot (Martybugs at en.wikipedia) [GFDL or CC BY 3.0], via Wikimedia Commons

            32. Platypus

            Ah the platypus, probably one of the strangest animals of Australia and the world. It’s the second egg laying mammal in this list and the oddest looking animal. They look so strange that people originally thought they weren’t real.

            By Peter Scheunis (Own work) [CC BY 1.0], via Wikimedia Commons

            33. Possum

            There are 23 species of possum in Australia but the common brushtail possum and the common ringtail possum are the ones you’re most likely to see. They’re nocturnal marsupials which happily live in urban areas. Both are about the size of a cat. Male possums are called a Jack, females are known as a Jill and the babies are Joeys.

            Photo by Greg Schecter – license

            34. Pygmy Possum

            A very strong contender for cutest Aussie animal is the pygmy possum. There are 4 different species: Western Pygmy Possum, Eastern Pygmy Possum, Tasmanian (or Little) Pygmy Possum and the Long-tailed Pygmy Possum. They’re tiny! They vary in length from 5cm to only 12cm and that’s from head to tail. They live in trees and help to maintain their own habitat by pollinating it as they’re nectar feeders.

            The tiny pygmy possum

            35. Quokka

            You made it – the cutest of all native Australian animals and the happiest creature on the planet. The awesome Quokka! Quokka’s are all over the place on Rottnest Island near Perth in Western Australia and they’re extremely friendly so you just have to go there! Rottnest Island is also a stunning place to visit even if they didn’t have Quokka’s.

            A cute Quokka on Rottnest Island

            36. Quoll

            Here’s another one of the native Australian animals that I’m surprised more people haven’t heard of because they’re so cute looking. Quoll’s are native to mainland Australia, Tasmania and New Guinea. They spend most of their day in a den and hunt at night. Quoll’s are sadly in decline due to urbanisation and introduced predators. They’re related to the now extinct Thylacine (Tasmanian Tiger).

            By Ways (Own work) [CC BY-SA 3.0], via Wikimedia Commons

            37. Snakes

            Snakes are fairly common in Australia and no doubt you’ll be aware that Australia has loads of deadly ones! There are about 140 snake species found in Australia, 32 of which are sea snakes. And although about 100 Australian snakes are venomous only 2 of them could kill you (though it’s highly unlikely!). The ones pictured below are the common tree snake, also known as the yellow-bellied black snake, green tree snake or grass snake. They’re very unlikely to bite, but if they do they aren’t venomous.

            Common Tree Snakes

            38. Spiders

            Ok, I’ll admit it, I’m terrified of spiders but in Australia you will see them, from the massive huntsman which moves disturbingly quickly to the bright red bottom of the redback spider. As you’ll be aware some Aussie spiders can be deadly, but most won’t bother you and even if you are bitten it’s unlikely you’ll die. Just be careful around these creepy crawlies!

            Huntsman Spider – pixabay

            39. Sugar Glider

            Sugar gliders are small marsupials which are fairly common in north and eastern coastal areas. They live in woodlands and glide between the trees at night searching for food.

            Photo by Joe McKenna – license

            40. Tasmanian Devil

            You look at the cute face of the Tasmanian devil and wonder how on earth it got its name but they’re notorious for their bad temper when they’re defending food, trying to find a mate or when a predator approaches. This carnivorous marsupial is endangered and its population is still decreasing. Sadly they’re suffering with a facial cancer that is contagious.

            Photo by Mathias Appel – license

            41. Thorny Devil

            The second devil on our list is a glorious looking lizard also known as a thorny dragon. Thorny devils are great at camouflage in the desert and even have a false head to confuse predators. They can also absorb water through any part of their body.

            By Christopher Watson (http://www.comebirdwatching.blogspot.com/) [CC BY-SA 3.0], via Wikimedia Commons

            42. Turtle

            There’s lots of freshwater and sea turtles that can be seen all around Australia. Heading to The Great Barrier Reef gives you the best chance to swim with wild turtles such as the loggerhead, hawksbill and the rarer green turtle. For an amazing experience head to Bundaberg during turtle hatching season to watch the baby turtles head to the sea for the first time after hatching.

            Turtles are a common sight in Australia

            43. Wallaby

            Wallabies are in fact kangaroos but wallaby is the informal name for those that are smaller than the kangaroos mentioned earlier. A group of wallabies is known as a ‘court’ a ‘mob’ or a ‘troupe’, I suppose depending on what they’re up to at the time! Look at that cute face!

            44. Wallaroo

            Like the wallaby a wallaroo is also in the same family as kangaroos. A wallaroo tends to be larger than a wallaby but smaller than a kangaroo.

            Photo by Peter Firminger – license

            45. Water Dragon

            The Australian water dragon is most commonly found in eastern Australia and very commonly seen in Brisbane. The one pictured below was spotted in Manly near Sydney. Water dragons are semi-aquatic and are therefore found near bodies of water, generally creeks, rivers or lakes with some rocks nearby to hang out on.

            Water Dragon spotted in Manly, Sydney

            46. Wombat

            Wombats are marsupials, but unlike most marsupials their pouch is backwards. They also do square poops. Wombats have strong claws on their short feet and look a bit like a fat gopher. They’re burrowing animals that live across Australia and Tasmania in forests, grasslands and even mountains. Being nocturnal, burrowing animals it’s unlikely you’ll see any in the wild even though they’re about the size of a medium dog.

            By JJ Harrison ([email protected]) – Own work , CC BY-SA 3.0, via Wikimedia Commons

            47. Yabby

            Yabbies are crayfish (basically small lobsters) that are a very popular seafood in Australia. It’s possible to find marine yabbies and freshwater yabbies. They come in a range of colours including blue, red and yellow. Yabbies can even survive periods of drought for several years by burrowing into riverbeds.

            Photo by Ioan Sameli – license

            Out of all the Aussie animals listed which is your favourite and why? What animals of Australia have I missed? I’ll add them in!

            Have you spotted any of Australia’s Big Animals? Like the Giant Koala, or the Big Penguin? No!? Here’s where to find Australia’s Big Things.


            Should Wild Animals Become Pets to Ward Off Extinction?

            To go native?

            Look at the following quotes opposing keeping native animals as pets. Decide if you agree or disagree and explain why.

            "Many major diseases - flu, smallpox, tuberculosis etc - originally came from human contact with animals when pigs, cattle and sheep were domesticated."

            "Keeping budgies has not contributed to parrot conservation, nor has the domestication of dogs and cats assisted efforts to conserve the wolf or large cats like the lion and tiger."

            " There are some sorts of problems too I think particularly in the case of things like bilbies, where you&rsquove got populations across Australia that have got different genetics, if we start putting them into a pet situation and we as a very mobile group of human beings who can be in Charleville one day and Perth the next day with our pets, there&rsquos potentially some sorts of problems in terms of mixing genetics up."

            "RSPCA Australia is opposed to the keeping of wild, native or introduced animals as pets or companions. Native animals require equally high standards of care as do any domestic pet, however it is much more difficult to adequately provide for them. In many cases they require specialised husbandry and facilities to mimic their natural environment and meet their physiological and ecological requirements. Most people do not have the skills, experience and facilities to do this (something evidenced by the difficulty many people have in providing adequate care for traditional types of companion animals). "

            &ldquoPeople procuring these unusual species for 'pets' often do so as an indication of (sic) social standing, or for a talking point. The animal's food and behavioural needs are often ignored, or not even known in the first place. Owners prefer cheap and easy method (sic)of feeding and housing. Many animals end up dumped and abandoned or sold to a succession(sic) owners."

            Invasive ferals

            New hope for Cane Toads
            The many unknown predators of the toad

            Rabbits
            A fence almost 2,000 km long to keep rabbits out of WA? Sounds like a great idea! If it doesn't work, we'll build another one!

            The Willow
            How a change in its status from asset to weed led to fish kills with blackwater and blue-green algae outbreaks

            To bait dingos?
            Should the health of the ecosystem be considered or just the kennel club registration?

            Koala control
            What to do about the "koala plague" on Kangaroo Island

            Cat
            Apex predator in Australia. Confined to urban areas in America.

            Environmental values

            Environmental problems
            How money and ideology shapes environmental "science."

            Bushfire
            Australia's Stockholm Syndrome with gum trees.

            Climate change in Australia
            Australia was once covered in rainforest. Could it be again?

            Sustainability
            The dark side of sustainable environmental policies

            Australian environmental science is defined by an ideology that is not unlike a prison warden. There, the scientists are not seeing themselves as part of the ecosystem, but as masters over it protecting the rights of the species that they say have rights and killing those that they say do not&hellipbut inevitably killing both.

            "It was always seen as desirable to remove or cull the introduced species. We also need to ask whether it was possible to do so, how it should be done, whether it could have unintended consequences and what it would cost? I don't think anyone really asked those questions." Physicist John Reid - 2012



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