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There are many references to eagle pushing their young off the nest to make them know how to fly, for example this motivational video.
It is also described in this website:
Let me show you "the ways of an eagle" in the nest, and give you a picture of our lives as well. After the eaglets get to a certain size, or maturity, everything changes! One day the mother eagle comes back from being gone, but this time there's no food in her beak, and she doesn't land on the edge of the nest. Instead, she hovers over the nest.
You may not know this, but an eagle can do almost what a hummingbird can do. Even though they are great birds, they can remain almost motionless in midair with those great wings just undulating in the breeze. They do this about three feet above the nest. I'm sure if little eagles could talk to one another-and maybe they can-one would certainly say, "My, what strong wings Mommy has."
Why does the mother do this? She is demonstrating that those curious appendages on the babies' backs have a useful function. Eagles, of course, were meant to fly, but they don't know that. If we take an eagle and separate it at birth from its parents, it will never learn to fly. It will just grovel around in the dirt like a chicken. It might even look up and see eagles soaring overhead and never guess that it was meant to soar in the heavens.
Eagles have to be taught, and that's the mother's job. So first she just demonstrates.
The next thing she does is come down into the nest and surprise her young. One can imagine how warm it must normally be for the little eagles to snuggle with their mother and be enshrouded with her feathers, but this time she puts her head up against one of the little ones, and pushes that little one closer and closer to the edge of the nest. ("Hey mom, mom, what are you doing?")
All at once she pushes the little one out of the nest, and the eaglet falls down the face of the cliff, surely to be destroyed. But not so! In a flash the great mother eagle flies down, catches the little one on her back, and flies up and deposits it in the nest. ("Whew! Mom, that must have been an accident.") But it wasn't an accident. The mother bird pushes the little one out again, and again, over and over.
Why would a mother do that to her young? Does she hates the little one? Not at all. It's just that those little birds were made to fly, and they don't know it, so she is going to push them out of the nest. She never lets them hit bottom, but she does let them fall, because they have to learn something they don't know.
The next time the mother bird comes back she decides to clean house, and so she stands on the edge of the nest. The first things to go are the feathers inside; she drops them over the edge. Then the leaves go over the edge-heave ho! While this is going on, she's not very talkative, either. ("Mom, what are you doing?") She pays no attention. Since she built the house, she knows how to take it apart.
Next she decides to take the sticks out of the middle of the nest, and with her great strong beak and feet, she's able to break them off and stand them straight up. ("Mom, it's not comfortable in here anymore.") Then she takes certain key sticks out of the nest and throws them over the edge. ("What are you doing, Mom? You are wrecking my room.")
She seemingly pays no attention to the concerns of her young as she prepares to pull the nest apart, for she is determined that those little ones will fly, and she knows something they don't. She knows they will never fly as long as they remain in the nest.
However, looking at this very interesting documentary on white-tailed eagle, the young eagles don't learn to fly by getting pushed as described in the motivational video, but they learned flying by practicing their wings on good winds.
Looking from the nesting place (cliff), I read that it might be Golden Eagle. But the section describing the fledgling doesn't say anything about the parent eagle pushing the young, although it does say about "jumping off":
The first attempted flight departure can be abrupt, with the young jumping off and using a series of short, stiff wing-beats to glide downward or being blown out of nest while wing-flapping. The initial flight often includes a short flight on unsteady wings followed by an uncontrolled landing.
Does Golden Eagle really push their young to teach them flying? If not, which species is it?
In case it's not clear, I am also interested in references that describes the eagle behavior in more details. It would be good if there is a video documentary, but considering that capturing this moment on tape might be difficult, that's not my utmost concern.
I am pretty sure this doesn't happen with eagles, and I have no idea why this would be written.
But not so! In a flash the great mother eagle flies down, catches the little one on her back, and flies up and deposits it in the nest. ("Whew! Mom, that must have been an accident.") But it wasn't an accident."
This is flight, alright: a pure flight of fancy.
There have been many hundreds of videocams set up in all kinds of remote locations so that behavior in the wild can be studied. Some of the most popular cams in recent years have been the eagle cams (e.g. at eagles.org). They are live during nesting season and record for all the behavior of eagles.
If the parents did not feed their young, as described in the fabrication above, the young would starve to death, as it takes time to learn to fly. If anything, the eagle parents must increase the feeding to keep up with the nutritional needs of the growing chicks, and the muscle building taking place. The parents don't stop feeding until a while after they're flying well.
Eagles don't learn "learn" why they have wings by observing the mother eagle hovering above them (pure anthropomorphizing). They leave the nest and start roaming on the branches, practicing hopping, landing, and building up their wing strength. Eventually flying, they still come back to the nest to feed. In this video from British Columbia (not the most exciting in the world) you can see exactly this happening with bald eagles. Eventually the young eagles scavenge and learn to hunt for themselves. It takes time. This page describes the fledgling feeding and flight behavior.
While I am not going to try to find an eagle that behaves in the bizarre manner you've found and asked about, I will say that eagles are eagles and more or less behave pretty similarly. The most common eagle in the world is the bald eagle. The Golden behaves like the Bald. Eagle behavior is influenced by habitat, etc. Wikipedia has a page listing 60 species of eagles. Picking a random eagle from another part of the world (in this case, the Sub-Saharan Martial eagle, this information seems to confirm that attentiveness of adult eagles and fledgling behavior is similar though not without species variation:
Martial eagles have a slow breeding rate, laying usually one egg (rarely two) every two years. The egg is incubated for 45 to 53 days and the chick fledged at 96 to 104 days. Despite increasing signs of independence (such as flight and beginning to practice hunting), juvenile birds will remain in the care of their parents for a further 6 to 12 months. Due to this long dependence period, these eagles can usually only mate in alternate years.
I'm sure I'm not the first to warn you not to believe everything you read on the internet.
With Eagles Wings
I want to take a break from the way I usually teach and simply reflect on eagles. I am fascinated by eagles, even though there is much about them I don’t understand. I have had encounters with eagles many times in my life and am always amazed by them. One summer I went with friends through the Inside Passage off Vancouver Island, and we watched eagles from the boat as they swooped down to catch fish out of the water. What amazing hunters/"fisherbirds" they are.
Last fall I traveled to the Skagit River on a stormy day to take pictures of eagles. They are so majestic and awe-inspiring. One of the phenomenons I have had with eagles is that at various times they have come out of nowhere and flown over my head! One time, exhausted and recovering from a total breakdown, crying out to God for strength, I had an eagle fly right over my head at the exact time I was asking for strength. I heard my heart quote a familiar verse: ". those who (wait) hope in the LORD will renew their strength. They will soar on wings like eagles. "—Isaiah 40:31.
Because of these experiences, I prepared a seminar I call Eagle Flight, in which I share spiritual disciplines or health habits that help us fly with the eagles. On this site, all the transcripts of my messages are found in the same section: Eagle Flight. Just as eagles are fascinating, I want to do what I can to show how fascinating Scripture is.
Obviously I am not the only person curious about and fascinated by eagles. Agur was amazed by eagles— Prov. 30:18: 18] "There are three things that are too amazing for me, four that I do not understand: (the first of the four is) 19] the way of an eagle in the sky. " The eagle amazed Agur and was often the symbol of vigor and vitality.
David saw the eagle as a symbol of strength, too. He says in Psalm 103:2, "Praise the LORD, O my soul, and forget not all his benefits" (David then lists several things and concludes with). (5) "who satisfies your desires with good things so that your youth is renewed like the eagle’s."
With those examples in mind, I want us to see that eagles are not only fascinating, amazing and symbolic of strength, but really do help us to see ourselves.
6 Traits of an Eagle
Eagles are uncommon birds, depicted in the Scriptures as a picture of the victorious Christian life. These six traits of eagles should encourage us to soar higher in our life of faith.
TRAIT #1: Eagles fly at high altitudes, not with low-flying birds like sparrows or other small birds.
Principle: If you want to be an eagle Christian, you need to fly with other eagles and stay away from sparrows and ravens.
TRAIT #2: Eagles have strong vision, with an ability to focus on objects up to three miles away. When an eagle sights his prey, he will not move his focus from the prey until he successfully captures it.
Principle: In order to succeed, we must have a clear vision and remain focused no matter what the obstacles may be.
TRAIT #3: Eagles feed only on fresh prey, never eating dead things. Vultures eat dead animals, but eagles will not.
Principle: Be careful about what you feed your eyes and ears with, especially on the Internet, movies, or TV.
TRAIT #4: When storm clouds gather, eagles get excited. An eagle uses the storm’s wind to lift himself higher, far above the clouds. In the meantime, all the other birds hide in the leaves and branches of the trees.
Principle: We can use the storms of life to rise to greater heights. High achievers thrive on challenges and use them profitably.
TRAIT #5: An eagle tests before it trusts. When a female eagle meets a male and they want to mate, she first tests his commitment. Then and only then, will she allow him to mate with her.
Principle: Whether in private life or in business, one should test the commitment of people intended for partnership.
TRAIT #6: During the time of training her young ones to fly, a mother eagle throws the eaglets out of the nest. Because they are scared, they jump into the nest again. Next, the mother eagle pushes the eaglets off the cliff into the air. As they shriek in fear, father eagle flies out and catches them up on his back and brings them back to the cliff. This goes on for some time until they learn to start using their wings to fly.
Principle: The people who love us do not let us languish in sloth but push us hard to grow and prosper. Even in their seemingly harsh actions, they have good intentions for us—and these steps are necessary to teach us to fly.
Eagles don’t always have a soft and easy life, nor will we. But just as eagles illustrate, God is calling us to wait on Him and learn to soar higher, above the cares, trials, and trivial pursuits of life:
Those who wait on the LORD shall renew their strength they shall mount up with wings like eagles, they shall run and not be weary, they shall walk and not faint. (Isaiah 40:31).
Myles Munroe was the founder of Bahamas Faith Ministries International in Nassau. Learn more at MunroeGlobal.com
Habitat and Range
The Verreaux’s Eagle is found only in Africa and they are particularly fond of the mountainous and rocky terrain of Eastern and Southern Africa. This eagle needs a rather large range in which to hunt, up to ten square kilometers.
While they are fairly concentrated along the eastern and southern parts of Africa there are also local pockets located in Chad and western Africa. The Verreaux’s Eagle needs this mountainous terrain with rocky ledges and cliffs in which to nest and hunt their favorite prey, the rock hyrax.
What species of eagle pushes their young to teach them flying? - Biology
Bald Eagle Nesting & Young
There are an estimated 7,066 nesting pairs of bald eagles, due to the efforts of federal agencies, tribes, state and local governments, conservation groups, universities, corporations, and thousands of individuals.
US map of estimated breeding pairs in each state.
Nests - The shape of the eagle nest or aerie is determined mainly by the branch point where it's built. Sticks placed in tree forks result in cylindrical or conical shaped nests. Disk shaped nests are built on the ground or a tree branch which is nearly level. Bowl shaped nests occur where the tree trunk branches off into smaller upright branches. Inverted cone shaped nest.
Bald eagles build their nests in large trees near rivers or coasts. A typical nest is around 5 feet in diameter. Eagles often use the same nest year after year. Over the years, some nests become enormous, as much as 9 feet in diameter, weighing two tons.
If the nest tree falls or a strong wind blows a nest down, the established pair usually rebuilds at or near the site within a few weeks if it is near the breeding season. A nesting pair will also build a new nest if they feel threatened. Essentially, it's not totally uncommon for eagles to build more than one nest within their nesting territory.
The nest is usually built in a tree, but may be built on a cliff or even on the ground if there are no other options available.
Eagles are territorial during nesting season. They will keep other eagles out of their own nesting territory, which is usually one to two square miles.
Sexual maturity - An eagle reaches sexual maturity at around four or five years of age. At that time, the eagle's energies become concentrated on the effort of finding a mate and raising offspring. Bald eagles mate for life, but when one dies, the survivor will not hesitate to accept a new mate.
During breeding season, both birds protect the nest territory from other eagles and predators.
Mating season - varies greatly by region. In the South it may last from late September through November, while in the Great Plains and Mountain West, it may last from January through March. In Alaska it lasts from late March to early April.
One way to determine the sex of an eagle is to examine its beak. Females have deeper (distance from top to chin) beaks than males.
Pairs of bald eagles have been seen whirling through the air with talons locked together. This could be a form of courtship or a ritualized battle between an intruding eagle and one defending its territory. Whichever it is, eagles do not actually copulate in the air. Copulation usually takes place on a branch near the nest or on the ground.
On rare occasions, bald eagles have remained locked together by their talons long enough to fall to the ground. I received an email telling of two talon locked eagles falling into a bush beside a person's home. They remained locked for about eight hours, and then unlocked and flew away. Another case reported in a Georgia newspaper article, tells of a locked pair falling to the ground in a golf course. They were stunned by the fall and remained locked for several hours. Only after one eagle was touched by a bystander, did they unlock and fly away.
Some eagles do not breed every year. Bald eagles are capable of breeding annually from the age of four, but some of the adults, though paired, seem to choose not to breed. It might be an instinctive decision, based on the weather availability of nesting sites, or food.
Because an eagle lives up to 30 years in the wild, it has many years in which to produce offspring.
Eggs - In the Vancouver area eggs are laid in late March and early April, while in northern Canada and Alaska eggs are laid in May. In Florida, eggs are laid from November through January.
Eagles lay from one to three eggs. Five to ten days after a successful copulation, the female lays a speckled off-white or buff colored egg about 2 1/4" X 3" in size, weighing about 4.5oz. The second egg is laid a few days later, followed by a possible third.Bald eagle nesting seasons The 35 days of incubation duties are shared by both male and female, but it is the female who spends most of her time on the nest. Trading places on the nest can be a tense time. The brooding parent may have to call for relief, or may be reluctant to leave and have to be pushed off the eggs or young. During incubation, the male bald eagle regularly brings green sprigs of conifer branches to the nest. Why he does this, no one knows, but it could be for deodorizing the nest or possibly providing shade for the eaglets.
During incubation, 98% of the time one parent remains on the nest not only to keep the eggs warm but to protect them from squirrels, ravens, and gulls which will break open and eat the eggs. If the adults leave the nest unattended too long, it can be consequential for the eggs. Diverse weather conditions could impact the temperature of the eggs leaving the eggs nonviable.
Human disturbance can have an impact on the bald eagle, as most of them need some privacy and quiet to breed. People wanting to observe or photograph the eagles can disturb them enough to cause them to abandon a nest. Use binoculars and spotting scopes for viewing, and keep at a reasonable distance.Bald eagle disturbance sensitivity chart during the nesting cycle. The eggs hatch in the order they were laid. Eaglets break through the shell by using their egg tooth, a pointed bump on the top of the beak. It can take from twelve to forty-eight hours to hatch after making the first break in the shell (pipping). Once the eggs begin to hatch, the female's vigilance becomes nearly constant. The male provides the majority of the food needed by his rapidly growing family. Eventually the female will take up her share of the hunting, but in the early days, all of her attention is given to the young eaglets in the nest.
Chicks - Sometimes two chicks will survive, but it is not uncommon for the older eaglet to kill the smaller one, especially if the older is a female, as females are consistently larger than males. Should one chick decide to kill its sibling, neither parent will make the slightest effort to stop the fratricide.
Newly hatched, eaglets are soft, grayish-white down covers their small bodies, their wobbly legs are too weak to hold their weight, and their eyes are partially closed eyes, limiting vision. Their only protection is their parents.
Eagles feed their young by shredding pieces of meat from their prey with their beaks. The female gently coaxes her tiny chick to take a morsel of meat from her beak. She will offer food again and again, eating rejected morsels herself, and then tearing off another piece for the eaglet.
While on the nest with very young eaglets, parents move about with their talons balled into fists to avoid accidentally skewering their offspring.
Eaglet Growth - The young birds grow rapidly, they add one pound to their body weight every four or five days. At about two weeks, it is possible for them to hold their head up for feeding.
By three weeks they are 1 foot high and their feet and beaks are very nearly adult size.
Between four and five weeks, the birds are able to stand, at which time they can began tearing up their own food.
At six weeks, the eaglets are very nearly as large as their parents.
At eight weeks, the appetites of the young birds are at their greatest. While parents hunt almost continuous to feed them, back at the nest the eaglets are beginning to stretch their wings in response to gusts of wind and may even be lifted off their feet for short periods.
At three or four weeks, this eaglet is covered in its secondary coat of gray down. In another two weeks or so, black juvenile feathers will begin to grow in. While downy feathers are excellent insulators, they are useless as air foils, and must be replaced with juvenile feathers before an eaglet can take its first flight, some 10 to 13 weeks after hatching.
Down is gradually replaced by feathers, while the eaglets grow still stronger. Finally, an important moment arrives.
In An Eagle to the Sky (1970), Frances Hamerstrom, who spent many hours observing eagles, described the process for one young bird:
The. EAGLET WAS now alone in the nest.
Each time a parent came flying in to toward the nest he called for food eagerly but over and over again, it came with empty feet, and the eaglet grew thinner. He pulled meat scraps from the old dry-up carcasses lying around the nest. he watched a sluggish carrion beetle, picked it up gingerly, and ate it. His first kill.
Days passed, and as he lost body fat be became quicker in his movements and paddled ever more lightly when the wind blew, scarcely touching the nest edge from time to time he was airborne for a moment or two.
Parents often flew past and sometimes fed him. Beating his wings and teetering on the edge of the nest, he screamed for food whenever one flew by. And a parent often flew past just out of reach, carrying delectable meals: a half-grown jack rabbit or a plump rat raided from a dump. Although he was hungry almost all the time, he was becoming more playful as he lost his baby fat sometimes, when no parent bird was in sight, he pounced ferociously on a scrap of prairie dog skin or on old bits of dried bone.
The male eaglet stayed by himself for the most part. He was no longer brooded at night. Hunger and the cold mountain nights were having their effect, not only on his body but on his disposition. A late frost hit the valley, and a night wind ruffled his feathers and chilled his body. When the sunlight reached the eyrie's (the brood in a nest of a bird of prey) edge, he sought its warmth and soon, again, he was bounding in the wind, now light and firm-muscled.
A parent flew by, downwind, dangling a young marmot in its feet. The eaglet almost lost his balance in his eagerness for food. Then the parent swung by again, closer, upwind, and riding the updraft by the eyrie, as though daring him to fly. Lifted light by the wind, he was airborne, flying--or more gliding--for the first time in his life. He sailed across the valley to make a scrambling, almost tumbling landing on a bare knoll. As he turned to get his bearings the parent dropped the young marmot nearby. Half running, half flying he pounced on it, mantled, and ate his fill.
Once the young eagles have fledged (to acquire the feathers necessary for flight) they remain around the nest for four or five weeks, taking short flights while their primary feathers grow and strengthen. Their parents still provide all of their food.
The young birds, with the exception of their color, resemble their parents, but are nothing like them in behavior. They have to learn how to hunt, and they only have the remainder of the summer to learn. After that, they're on their own. The first winter is the most dangerous and difficult part of an eagle's life.
Higher predators are born with instincts that urge them to fly, to bite or to pounce, but precisely how to do these things is another matter. Through months of trial and error, eagles acquire basic skills such as lighting on perches or stooping on prey through practice. Eagles practice with almost fully developed bodies, and so sharpen their skills quickly.
An immature bald eagle is sometimes mistaken for a golden eagle. However, a young bald eagle has more white mottled into its coloration overall a golden eagle is more solid in color, and its beak is more blue-black with a nearly black tip.
Eagles molt in patches, taking almost half a year to replace feathers, starting with the head and working downward. Not all feathers are replaced in a given molt. Until the bald eagle is mature, the replacement feathers are of different colors. As adults, the belly and back are dark, while the head is pure white. The distinct juvenile pattern, signaling that a bird is not ready to breed, may reduce aggression from territorial adults.
As juvenile bald eagles mature, their head and tail feathers gradually turn white simultaneously the eyes and beak gradually turn yellow. Complete transformation to maturity is achieved sometime in the fifth year.
After fledging, young eagles stay near the nest for six to nine weeks practicing their ability to fly and hunt. The parents cannot tell juveniles how to hunt, they have to learn by watching the parents and practicing. During this time, they seem to spend more time looking at prey than they do actually attacking it.
Until the first winter after they fledge, young eagles near the nest are often still fed by their parents, but have little other contact with them. Although a young eagle has the instincts to hunt, it lacks the skills. Eventually, they learn to soar and spot prey. If food is scarce during the winter, it could die. Approximately 50% of young eagles do not survive their first year.
Nesting cycle - From the time the parents build the nest and the young are on their own, takes about 20 weeks. During the nesting cycle the parents remain within one to two miles of the nest.
Communal gatherings of bald eagles offer many advantages to younger inexperienced eagles. Not only is food abundant on the salmon spawning grounds, but here the juveniles can watch their elders to learn how food is caught. They also learn very quickly how to steal food.
The information and photos on this web site may be used for student projects as long as neither are placed on other websites. The photographs are copyrighted by Hope Rutledge, the owner and author of the American Bald Eagle Information website, and are NOT available for other websites, photo galleries or commercial use of any kind.
DFW Raptors – Hawks, Falcons, and Eagles
Many people hold a particular fascination with raptors&mdashotherwise known as birds of prey. I know I do. These big, powerful birds inspire us with their raw power, grace and majesty. So respected are these birds that they are often chosen as sports team mascots. Many countries use birds of prey as their national symbol.
The DFW Metroplex is home to a number of these mighty birds. Depending on the season, there can be as many as 20 different species of falconiformes living in the North Texas area. Some are seasonal migrants. Other are what is known as occasional vagrants&mdashbirds that sometimes roam outside their normal range. When you’re as big and powerful as a raptor soaring high in the sky, moving outside your home range is not difficult to do.
Buteos – Medium to large-sized Raptors with robust bodies and broad wings.
Perhaps the most common of all of our raptors is the Red-tailed Hawk (Buteo jamaicensis). These ubiquitous hawks are widely distributed across all of North America, and are superbly adapted to urban living. They breed readily around human populations, and often make use of man-made structures as nest locations. Urban Red-tailed Hawks can frequently be seen perched on lampposts along our highways where they stay on the look out for prey animals in the grassy medians. Red-tailed Hawks are year round residents, but their numbers increase in the winter when northern populations migrate into Texas.
The Red-tailed Hawk is a large bird with a wingspan that can approach 5 feet. The plumage displayed by this bird can vary widely depending upon age, color morph, and whether migratory subspecies are in the area. Most adult Red-tailed Hawks in the DFW area, however, display the namesake red tail, a dark band across a white breast, and light wings with a dark bar along the leading edge.
Red-tailed Hawks typically feed on small mammals such as Eastern Cottontails, Fox Squirrels, rats, and mice. Occasionally they will feed on common urban birds like feral pigeons or starlings.
More information about Red-tailed Hawks can be found here: Wikipedia – Red-tailed Hawk
A Red-tailed Hawk clearly displaying its signature red tail. A juvenile Red-tailed Hawk, only days out of the nest. A Red-tailed Hawk photographed near its nest located atop a cell phone tower.
Perhaps the second most common Buteo in the metroplex is the Red-shouldered Hawk (Buteo lineatus). Although very numerous in North Texas and a year round resident, the Red-shouldered Hawk is not often seen. This is because the Red-shouldered Hawk prefers heavily wooded areas along rivers and creeks. In North Texas that means the Trinity River and its various tributaries.
These hawks breed readily in and around the metroplex, but they seldom make use of man-made structures when choosing a nesting site. Instead red-shouldered Hawks prefer to nest in tall trees located in riparian forests. Red-shouldered Hawk feed on small mammals and reptiles. Snakes are a favorite food.
The Red-shouldered Hawk is slightly smaller than the more common Red-tailed Hawk. It is easily distinguishable by its red chest and shoulders, and by its starkly black and white striped wings and tail when in flight.
More information about Red-shouldered Hawks can be found here: Wikipedia – Red-shouldered Hawk
A Red-shouldered Hawk surveying his domain. A young Red-shouldered Hawk taking flight.
The Swainson’s Hawk (Buteo swainsoni) is another large Buteo frequently seen around the DFW Area in the summer time. Swainson’s Hawks spend their winters in South America, and only reach portions of the United States after a long springtime migration.
The Swainson’s Hawk is usually seen at altitude, soaring high over our urban development. In the air they are recognizable by their unique colors and configuration. Swainson’s Hawks have darkly colored heads and light undersides. Their flight feathers create a contrasting darkly colored trailing edge on their wings. In flight, the wings of these Buteos often appears narrower and more pointed that those of other similar species.
The metroplex is just at the edge of the Swainson’s Hawk beeding range, and presumably they do nest here&mdashthough I have yet to come across one of their nest. Swainson’s Hawks are much less tolerant of human activity than some of our other hawks, and therefore may nest in more rural and isolated areas.
Unusual for a hawk of this size, the diet of Swainson’s Hawk can largely consist of insects.
More information about Swainson’s Hawks can be found here: Wikipedia – Swainson’s Hawk
Swainson’s Hawk. Photograph courtesy Wikimedia Commons. Swainson’s Hawk in flight. Photograph courtesy Wikimedia Commons.
Other, less common, Buteos can be seen in the metroplex from time to time. These birds reach our area as migrants or as occasional vagrants.Though rarely seen, these hawks will be spotted by sharp-eyed birders from time to time.
The Broad-winged Hawk (Buteo platypterus) is a small hawk that is usually seen during its fall and spring migrations. At these times great kettles of Broad-wings Hawks may be seen passing high overhead as they make their way to and from South America.
Broad-winged Hawks have been know to breed in the metroplex, but Dallas/Fort Worth represents the western most limits of their summer distribution. Incidents of breeding Broad-wings Hawks increases as one travels into the eastern United States.
More information about Broad-winged Hawks can be found here: Wikipedia – Broad-winged Hawk
A Broad-winged Hawk at Altitude. Photograph courtesy Wikimedia Commons. Broad-winged Hawk – Photograph courtesy Wikimedia Commons.
The handsome Harris Hawk (Parabuteo unicinctus) is another Buteo that occasionally makes its way to the metroplex during the winter months. These hawks are seldom seen in North Texas.
More information about Harris Hawks can be found here: Wikipedia – Harris Hawk
Harris Hawk – Photograph courtesy Wikimedia Commons.
The Ferruginous Hawk (Buteo regalis) is a rare winter visitor to the metroplex. They are most likely to be be seen on prairies in our western most counties during the coldest winter months.
More information about Ferruginous Hawks can be found here: Wikipedia – Ferruginous Hawk
A Ferruginous Hawk in flight. Photograph courtesy Wikimedia Commons Ferruginous Hawk – Photograph courtesy Wikimedia Commons
Rough-legged Hawks (Buteo lagopus) may make their way down into our northern counties during the coldest months of winter. Prairies and pastures well away from developed areas are where they are most likely to be found.
More information about Rough-legged Hawks can be found here: Wikipedia – Rough-legged Hawk
Rough-legged Hawk – Photograph courtesy Wikimedia Commons /> Click to Enlarge
Accipiters – Woodland hawks with short wings and long tails
There are two species of Accipters to be found in the North Texas area&mdashthe Cooper’s Hawk and the Sharp-shinned Hawk. These two species are remarkably similar to each other in general apperance. Both sport nearly identical plumage coloration. Size is the primary differentiator, as the Cooper’s Hawk is usually significantly larger than the Sharp-shinned Hawk.
Of the two, the Cooper’s Hawk (Accipiter cooperii) is the most commonly observed. It is a year round resident in the DFW metroplex, and is beginning to breed more readily in our cities.
Adult Cooper’s Hawks are medium-sized raptors. They have slate gray plumage with a red and white herringbone pattern on their breast and wing leading edges. Tail and flight feather show black and white stripes when viewed from below.
Cooper’s Hawks are well adapted to hunting in wooded areas, and feed largely on other birds. A well stocked bird feeder that attracts a constant crowd of song birds might also attract a hungry Cooper’s Hawk to your backyard as well.
More information about Cooper’s Hawks can be found here: Wikipedia – Cooper’s Hawk
Cooper’s Hawk A big female Cooper’s Hawk feeding on a feral pigeon. A Cooper’s Hawk attempting to drown a recently captured European Starling in a small roadside puddle. A juvenile Cooper’s Hawk
The smaller Sharped-shinned Hawk (Accipiter striatus) is very similar in appearance to the Copper’s Hawk. Key differences include a shorter, square cut tail, and a large-eyed, more gentle appearance about the face. Sharp-shinned Hawks are in the DFW Area only in the winter months.
Like the Cooper’s Hawk, Sharp-shinned Hawks are well adapted to woodland hunting a preferred to feed on small birds.
More information about Sharp-shinned Hawks can be found here: Wikipedia – Sharp-shinned Hawk
Sharp-shinned Hawk – Photograph courtesy Wikimedia Commons. Click to Enlarge
Falcons – Sleek aerobatic raptors with long pointed wings
The most common falcon in the Dallas/Fort Worth Metroplex is the American Kestrel (Falco sparverius). This small, Blue Jay-sized raptor can frequently be seen perched on utility wires overlooking open fields and vacant lots. The American Kestrel is a strikingly beautiful bird with a multicolored plumage that includes slate gray, yellow, orange, black, and white. The male of the species is particularly exotic looking.
These birds are year round residents in North Texas and breed readily in urban areas. They are cavity nesters and will make use of man made structures near suitable hunting grounds for their nesting needs.
The diet of the American Kestrel consist largely of insects, but they will also feed on small mammals, birds, and reptiles.
More information about American Kestrels can be found here: Wikipedia – American Kestrel
A male American Kestrel feeding on a small lizard. A kestrel with a recently captured mouse. A female American Kestrel taking flight. A mated pair. the female is on the left and the male is on the right.
The Merlin (Falco columbarius) is also sometimes seen in the metroplex. These small falcons&mdashonly slightly larger than the American Kestrel&mdashcan be found in North Texas during the winter months, and may be more evident during the fall and spring migrations.
More information about Merlins can be found here: Wikipedia – Merlin
Merlin – Photograph courtesy of Wikimedia Commons.
A few other species of falcon may sometimes wander into the metroplex. The Prairie Falcon (Falco mexicanus) is a rare winter visitor. It is typically only seen in our western most counties.
More information about Prairie Falcons can be found here: Wikipedia – Prairie Falcon
Prairie Falcon – Photograph courtesy of Wikimedia Commons.
The well know Peregrine Falcon (Falco peregrinus) also makes it into the metroplex from time to time. A rarely seen vagrant, Peregrine Falcons are only likely to be seen during their fall and spring migrations.
More information about Peregrine Falcons can be found here: Wikipedia – Peregrine Falcon
Peregrine Falcon – Photograph courtesy of Wikimedia Commons Click to Enlarge
Kites – Small raptors known for their graceful flight
The Mississippi Kite (Ictinia mississippiensis) is the most commonly seen kite in North Texas. These uniformly gray birds are the raptor world’s analog to an Air Force fighter jet.
The breeding range of Mississippi Kites has only recently expanded into North Texas. They now readily nest here, preferring bottomland forests near rivers and creeks for their breeding grounds. They are locally abundant in some places and large congregations may form in late summer as their young begin to leave the nest.
These birds feed primarily upon insects like dragonflies and grasshoppers, and they can frequently be seen feeding while in flight.
More information about Mississippi Kites can be found here: Wikipedia – Mississippi Kite
A quizzical Mississippi Kite
Seeing a Swallow-tailed Kite (Elanoides forficatus) in the metroplex is an exciting occasion. They are seldom seen here, but they seem to be expanding their range, and may even be breeding in certain areas in our most southeastern counties. Swallow-tailed Kites are beautiful raptors dressed in a plumages of white, gray, and black feathers. The Swallow-tailed Kite’s most notable trait is long forked “swallow tail”. Only slightly larger than the more common Mississippi Kite, the Swallow-tailed Kite is unmistakable for anything else when seen in flight.
More information about Swallow-tailed Kites can be found here: Wikipedia – Swallow-tailed Kite
A Swallow-tailed Kite as seen from above. A Swallow-tailed Kite in flight.
White-tailed Kites (Elanus leucurus) are almost never seen in the DFW Metroplex. Year round populations exist in far south Texas. Occasionally one will make it way into the metroplex. In 2013 a White-tailed Kite was photographed in North Texas near Lewisville Lake. You can read about that account on this Facebook page: White-tailed Kite at LLELA Lewisville Lake.
More information about White-tailed Kites can be found here: Wikipedia – White-tailed Kite
A White-tailed Kite in flight. Photograph courtesy of Wikimedia Commons. White-tailed Kite – Photograph courtesy of Wikimedia Commons. /> Click to Enlarge
Eagles – Large, powerfully built birds of prey
When it comes to raptors the Bald Eagle (Haliaeetus leucocephalus) may be the first bird to come to mind for most people in the United States. Our national symbol, the Bald Eagle has a power and grace that is nothing short of awe inspiring. These large birds of prey are uniformly dark brown in color except for their distinctive white heads and tails. Bright yellow beaks, eyes, and talons round out the Bald Eagle’s distinctive appearance. Juveniles sport a blotchy brown plumage and take up to five years to develop the more familiar look of the adult birds.
Bald Eagles have recently been removed from the endangered species list. The are becoming more abundance and they are expanding their range. Bald Eagles can frequently be seen in the Dallas/Fort Worth area, especially in the winter when many migratory eagles arrive in North Texas. These eagles feed primarily on fish and water fowl, making area lakes and rivers great places to try and see one. We even have some year round resident eagles in the metroplex, and a few breeding pairs. Some of theses eagles finding new ways to adapt to the presence of people.
More information about Bald Eagles can be found here: Wikipedia – Bald Eagle
A mated pair of Bald Eagles. A Bald Eagle carrying a fish in its talons. A pair of Bald Eagles and their nest on a transmission tower in Kaufman County.
The Golden Eagle (Aquila chrysaetos) will not be frequently seen in the North Texas area. This powerful bird of prey is native to the western most part of the continent, and may only occasionally roam into the DFW Metroplex in the winter. Adult birds can somewhat resemble juvenile Bald Eagles, so great care must be taken when identifying this rare vagrant.
More information about Golden Eagles can be found here: Wikipedia – Golden Eagle
Golden Eagle – Photograph courtesy of Wikimedia Commons. Click to Enlarge
Others – Caracaras, Ospreys, and Harriers
Crested Caracaras (Caracara cheriway) are very distinctive looking birds. The caracara is covered in a dark plumage. Its head is colored white with a dark crown. Wing tips and tail feathers are white with fine black striping. The caracara’s legs are long and yellow, and its beak is a pale red tipped with gray. They superficially resemble Bald Eagles and can be mistaken as such under certain viewing conditions.
The Crested Caracaras is becoming more common in the metroplex, as native populations in the south expand their range. Our southern counties provide the best opportunity for seeing a Crested Caracara.
These birds will feed on carrion and can often be found congregating with Black Vultures and Turkey Vultures around the carcass of a dead animal.
More information about Crested Caracaras can be found here: Wikipedia – Crested Caracara
A Crested Caracara (top) flying with a Turkey Vulture (bottom). A Crested Caracara in flight. A Crested Caracara photographed in Kaufman County.
Osprey (Pandion haliaetus) are superbly adapted for catching fish. This large raptor also goes by the names sea hawk, fish eagle, river hawk, or fish hawk. These birds become common in the winter around our larger lakes and rivers as northern populations migrate south. We even have a small resident population that can be found in certain locations year round.
As you might suspect, the Osprey’s diet consist almost exclusively of fish. These birds have several special adapations to help them catch fish&mdashlong curved talons being the most obvious of these. Further, the Osprey’s outer toe is reversible, which allows these raptors to grasp their slippery prey with two toes in the front and two in the back.
More information about Ospreys can be found here: Wikipedia – Osprey
An Osprey in flight. An Osprey over the Trinity River. An Osprey watching for fish from his perch high on a dead tree.
Northern Harriers are unique raptors with the body of a hawk or falcon and dish-shaped face of owl. Northern Harriers make their way into North Texas during the winter months. Once here they can often be seen hunting low over marshy wetland areas. Harriers feed on any small animal that might be found in habitats like these. Small mammals, birds, reptiles, and amphibians are all likely prey for the Northern Harrier.
Males and females of these medium-sized raptors differ in appearance. Females are brown with light undersides. Males also have lightly colored undersides but are slate gray on top and have dark wing tips. Both males and females sport a distinctive white stripe at the base of their tail that is an unmistakeable identifier. Both sexes also have an owlish face which is thought to help funnel sounds to their ears to help them pinpoint prey animals hidden beneath vegetation.
More information about Northern Harriers can be found here: Wikipedia – Northern Harrier
A female Northern Harrier hunting low to the ground. A female Northern Harrier in flight. A male Northern Harrier.
Common Grackles are large, lanky blackbirds with long legs and long tails. The head is flat and the bill is longer than in most blackbirds, with the hint of a downward curve. In flight, the wings appear short in comparison to the tail. Males are slightly larger than females.
Larger than a Red-winged Blackbird about the same size as a Mourning Dove
- Both Sexes
- Length: 11.0-13.4 in (28-34 cm)
- Weight: 2.6-5.0 oz (74-142 g)
- Wingspan: 14.2-18.1 in (36-46 cm)
Common Grackles appear black from a distance, but up close their glossy purple heads contrast with bronzy-iridescent bodies. A bright golden eye gives grackles an intent expression. Females are slightly less glossy than males. Young birds are dark brown with a dark eye.
You’ll often find Common Grackles in large flocks, flying or foraging on lawns and in agricultural fields. They strut on their long legs, pecking for food rather than scratching. At feeders Common Grackles dominate smaller birds. When resting they sit atop trees or on telephone lines, keeping up a raucous chattering. Flight is direct, with stiff wingbeats.
Common Grackles thrive around agricultural fields, feedlots, city parks, and suburban lawns. They’re also common in open habitats including woodland, forest edges, meadows, and marshes.
#2021MMM Sweet Sixteen
TONIGHT'S #2021MMM SWEET 16 WINNERS: Sea Star, Dugong, Red Kangaroo, Hartebeest, Anchovy, Tapir, Sphinx Monkey, and Harpy Eagle. We will see you tomorrow 3/24 at 8PM EST for the Elite 8 battles! pic.twitter.com/paekbPPwLf&mdash March Mammal Madness (@2021MMMletsgo) March 25, 2021
Round 3, Sweet Sixteen Results: Midgardia Seastar, Dugong, Red Kangaroo, Red Hartebeest, Saber-Toothed Anchovy, Mountain Tapir, Sphinx Monkey, and Harpy Eagle ADVANCE.
Sports Summaries by Prof Kate Lesciotto, Sam Houston State University
Midgardia Seastar (2) v. Ammonite (6) &ndash We spend the first part of this battle just trying to figure out what exactly these two combatants are! Seastars are also known as starfish but are not fish. They are echinoderms, and Midgardia Seastar belongs to an order of primarily deep-sea animals. Ammonite is a type of cephalopod, like squid, octopus, and nautilus, with a very distinctive shell. Ammonites are also called snakestone because their fossilized remains resemble a coiled snake turned to stone. In the deep waters of the Gulf of Mexico, around 760 m below the surface, Midgardia Seastar is raising her arms up for suspension feeding, in which some species use the spines on their arms like velcro to catch prey. At this depth, Ammonite is cold &hellip but not too cold. Near the seafloor, Ammonite is floating just above the waving arms of Midgardia Seastar as it drops lower for a closer look. Midgardia Seastar remains unaware of the descending doom. Other shelled cephalopods, like nautiloids, spend their days between 200-800 m in depth, while internally shelled cephalopods like squid can go much deeper, up to 1900m! This field of battle at 700+ m below the surface is experiencing
1041 pounds of pressure per square inch. Midgardia Seastar is adapted to this pressure, and Ammonite descends lower and lower. POP. Ammonite implodes! With a different shell than nautiloids, Ammonite&rsquos structural integrity maxed out and couldn&rsquot take the crushing pressure. MIDGARDIA SEASTAR outlasts Ammonite!! Narrated by Prof Jessica Light.
Dugong (1) v. Egyptian Fruit Bat (12) &ndash Both Dugong and underdog of the season Egyptian Fruit Bat have sailed through the first two rounds with relative ease and without injury. However, neither experiences a life of &lsquorelative ease&rsquo in relation to human interactions. Egyptian Fruit Bat populations are vulnerable to subsistence hunting and persecution due to fears of zoonotic disease, while Dugong is threatened by accidental entanglement in mesh fishing nets and pollution. But in the glistening waters of Wali El-Gemal National Park in Egypt, Dugong is busy enjoying another meal of seagrass and leaving a dusty plume of excavated sand in its wake. Flying overhead, Egyptian Fruit Bat is a few hundred kilometers from its home range and becomes disoriented by the bright sunlight and glistening waters of the Red Sea. Trying to dip down for a quick splash of cool water, Egyptian Fruit Bat is thrown off balance by a wave! Flapping his wings in an awkward imitation of a butterfly stroke, Egyptian Fruit Bat tires and begins to sink as it is promptly engulfed in the jaws of a large, 4-meter tiger shark (#GarbageCanOfTheSea)! This tiger shark had been aiming for its preferred prey &ndash Dugong. Dugong lifts its head from the sand just in time to see the gaping maw of the shark as it closes around Egyptian Fruit Bat&rsquos flailing body. With a surprising burst of speed, Dugong turns tail and heads for safer waters. DUGONG out-survives Egyptian Fruit Bat. Narrated by Dr. Alyson Brokaw.
Red Kangaroo (1) v. Red Brocket (5) &ndash Red Kangaroo may be listed as of &ldquoleast concern&rdquo in terms of conservation but was of great concern to Southern Red-Backed Vole and Red-Crested Tree Rat in previous battles. Peruvian hunters use Red Brocket as an important source of food and income, but this hunting is sustainable &ndash deforestation that has caused habitat loss is more concerning. In the Australian Botanic Garden Mount Annan, Red Kangaroo is grazing with his &lsquomob&rsquo of other kangaroos in an area with few shrubs, which can pose a tripping hazard. Without these shrubs for cover, Red Kangaroo quickly spots Red Brocket and efficiently hops over to investigate. Red Brocket freezes, hoping to go unnoticed by this terrifying new creature. As Red Kangaroo continues his approach and stomps the ground, Red Brocket realizes that today is not the day to make a stand and leaps away towards an escape. RED KANGAROO chases off Red Brocket. Narrated by Prof Marc Kissel.
Red Hartebeest (2) v. Bay Cat (3) &ndash Another set of animals has eased through the first two rounds, but both Red Hartebeest and Bay Cat have their own concerns. Endangered Bay Cat has to deal with the threat of their home habitat being converted to palm oil plantations, and Red Hartebeest is luckily rebounding after populations were driven down by hunting. But tonight, Red Hartebeest is relaxing in the Kgalagadi Transfrontier Park in South Africa when he spots a hungry cheetah. This cheetah is young, though, and known for trying to take on inappropriately sized prey. As Red Hartebeest squares up and stares down the cheetah, the feline decides not to tangle with those horns and runs off. Red Hartebeest returns to his termite mound but is now being stalked by Bay Cat. Although Bay Cat takes the time for appropriate recon, he ultimately decides that maybe this wouldn&rsquot be a good battle. As Bay Cay tries to slink away, Red Hartebeest spots it! Thinking it might be the cheetah back for another round, Red Hartebeest starts snorting and tossing its horns in classic aggressive behavior. Bay Cat turns tail and quickly runs away from the field of battle (#CatScandal). RED HARTEBEEST chases off Bay Cat. Narrated by Dr. Asia Murphy & Dr. Anne Hilborn.
Saber-Toothed Anchovy (1) v. Vampire Squid (5) &ndash After escaping from Basket Star and Black Dragonfish, Vampire Squid finds itself in the warm, shallow waters off the coast of what will become Pakistan, as Saber-Toothed Anchovy is on patrol. Adapted to the cold and dark of the deep sea, Vampire Squid is in a horrifying (to it) new world of new smells and bright light. Its large eyes &ndash 1 inch eyes on a 6 inch creature &ndash make this light quite painful! However, the blinding light is only the beginning of Vampire Squid&rsquos problems, as it has a body adapted to the pressures of the deep sea, and these shallow waters are causing rapid depressurization. Murky waters from a recent rain are the only saving grace to help hide Vampire Squid. Saber-Toothed Anchovy isn&rsquot bothered by murky waters. It has an air bladder for maintaining optimal buoyancy that extends into its skull where it is hypothesized to act as a subwoofer to collect and magnify low sounds &hellip including the ultrasound noises of thrashing prey. A blinded Vampire Squid is in the throes of pain as its organs expand with no support, and it comes as a mercy when Saber-Toothed Anchovy uses its eponymous dentition. The murky water takes on a sheen of red, and a silver flash of scales is the only evidence left. SABER-TOOTHED ANCHOVY defeats Vampire Squid. Narrated by Prof Josh Drew.
Red Wolf (2) v. Mountain Tapir (3) &ndash The tricksy taxonomy of Red Wolf will likely not be resolved until the genomes of ancient red wolves are analyzed &ndash current populations show high proportions of coyote gene flow. Mountain Tapir has some of its own tricksy taxonomy tucked up its odd-toed ungulate sleeve, with some unique trypanosome parasites that have mysterious intermediate hosts (Ticks? Leeches? Who knows!). Although not its actual habitat, Mountain Tapir is feeling right at home in the hilly grasslands and shrublands of the southeastern corner of North America during the 13th century, when Red Wolf lived among the Cherokee people. Mountain Tapir starts nom-noming on some leafy greens, but this isn&rsquot gratuitous #PlantCarnage. The digestive tract aids in the germination of many plant seeds, and Mountain Tapir is thought to be an important seed disperser. A strange smell on the wind causes Mountain Tapir to raise its proboscis &hellip canid predators are somewhere nearby. Spring can be difficult, with new vegetation making it harder to track prey, but Red Wolf has caught the scent of something and moves in! Mountain Tapir tries to escape by sliding down a hill on its rump, a behavior that reportedly wears the fur away and leaves bare patches of skin on their behinds. Red Wolf is hungry and in hot pursuit! With nowhere left to go, Mountain Tapir falls back on its signature move against bush dogs: stomp the floor and make frequent loud whistles. Used to eating much smaller mammals than Mountain Tapir, Red Wolf decides that this loud and odd looking animal could actually do some damage in a fight and moves on in search of more familiar prey. MOUNTAIN TAPIR defeats Red Wolf. Narrated by Prof Patrice Connors & Dr. Brian Tanis.
Sphinx Monkey (6) v. Blue-Capped Ifrit (7) &ndash These combatants enter the Sweet Sixteen with a few meals under their belts &ndash Sphinx Monkey brutally devoured Bush Squirrel in Round 1, and Blue-Capped Ifrit got a snack of Crypt-Keeper Wasp in Round 2. Sometimes Sphinx Monkey (aka Mandrill) find itself being a meal for humans, meaning that conservationists must work with resident communities to find sustainable alternatives to game hunting. The batrachotoxins in Blue-Capped Ifrit's skin and feathers can cause numbness, tingling, and sneezing in humans, meaning that humans typically only interact indirectly with these birds. In Mandrill&rsquos home habitat of the Lékédi Park in Southern Gabon, Blue-Capped Ifrit spots a large congregation of unfamiliar creatures with resplendent colors, including a face of fine blue, with the ridge and tip of the nose a brilliant red. While Mandrill sits and forages with his troop, Blue-Capped Ifrit spies a beetle scrambling through the leaf litter and snatches it. Blue-Capped Ifrit&rsquos beak crushes the beetle&rsquos exoskeleton but drops the beetle in surprise as he is grabbed from behind! Trying to fly away is futile, as Mandrill has a firm grip and uses its great canines to deliver a craniocervical killing bite. PTHW-WHTTT! Mandrill spits out feathers and pieces of skull as he feels the immediate effect of the batrachotoxins. Luckily, toxin levels are lower in the head feathers, but Mandrill still spits out the remainder of Blue-Capped Ifrit and returns to forage on safer fruits. SPHINX MONKEY dispatches Blue-Capped Ifrit!!! Narrated by Dr. Lara Durgavich.
Harpy Eagle (1) v. Devil Frog (5) &ndash Although listed as &ldquoNear Threatened,&rdquo Harpy Eagle populations have managed to maintain a high level of genetic diversity, suggesting a conservation strategy that focuses on multiple diverse local populations, rather than any single existing population. Devil Frog is about 65-70 million years away from its home habitat. Through comparisons with living relatives, such as South American horned frogs, scientists have inferred that the bite force of Devil Frog may overlap with the bite force range of hyenas and even exceeds that of coyotes! That bite force may not be the only trait on display in tonight&rsquos battle in Tambopata National Reserve in Peru. As Devil Frog walks (having legs that were likely too short to hop), it snaps a twig and draws the attention of Harpy Eagle. Smaller gray feathers along a facial disk may focus sound waves and improve Harpy Eagle&rsquos hearing. Mistaking Devil Frog for its more typical iguana prey, Harpy Eagle strikes but is repelled by Devil Frog&rsquos spiked and armored back &ndash no surprise, since beachball-sized Devil Frog&rsquos armor-like plates are believed to have fended off crocodile and dinosaur attacks. Devil Frog snaps at Harpy Eagle in a counterattack but misses! The miss causes Devil Frog to get off-balance, and it trips over a log. With Devil Frog&rsquos soft underbelly now exposed, Harpy Eagle uses its 5-inch talons to slice open the amphibian. HARPY EAGLE defeats Devil Frog!! Narrated by Prof Chris Anderson.
The willie wagtail was first described by the English ornithologist John Latham in 1801 as Turdus leucophrys.  Its specific epithet is derived from the Ancient Greek words leukos "white" and ǒphrys "eyebrow".  Other early scientific names include Muscicapa tricolor by Vieillot,  and Rhipidura motacilloides by naturalists Nicholas Aylward Vigors and Thomas Horsfield in 1827, who erected the genus Rhipidura.  The generic term is derived from the Ancient Greek rhipis "fan" and oura "tail". 
John Gould and other early writers referred to the species as the black-and-white fantail, although did note the current name. However, willie wagtail rapidly became widely accepted sometime after 1916. Wagtail is derived from its active behaviour, while the origins of willie are obscure.  The name had been in use colloquially for the pied subspecies of the white wagtail (Motacilla alba) on the Isle of Man,  and Northern Ireland. 
Other vernacular names applied include shepherd's companion (because it accompanied livestock), frogbird, morning bird, and Australian nightingale.  Many Aboriginal names are onomatopoeic, based on the sound of its scolding call.  Djididjidi is a name from the Kimberley,  and djikirridj-djikirridj is used by the Kunwinjku of western Arnhem Land.   In Central Australia, southwest of Alice Springs, the Pitjantjatjara word is tjintir-tjintir(pa).  Among the Kamilaroi, it is thirrithirri.  In Bougainville Island, it is called tsiropen in the Banoni language from the west coast,  and in Awaipa of Kieta district it is maneka.  In the Solomon Islands Pijin it is sometimes called the polis (police) or pris (priest) bird, because of its black-and-white colouring.
The willie wagtail is unrelated to the Eurasian wagtails of the family Motacillidae. It is one of 47 members of the fantail genus Rhipidura some authorities classify this group of birds as a subfamily Rhipidurinae within the drongo family Dicruridae, together with the monarch flycatchers,  while others consider them distinct enough to warrant their own family Rhipiduridae.  Early molecular research in the late 1980s and early 1990s revealed that the fantails belong to a large group of mainly Australasian birds known as the parvorder Corvida comprising many tropical and Australian passerines.  More recently, the grouping has been refined somewhat and the fantails have been classified in a "core corvine" group with the crows and ravens, shrikes, birds of paradise, monarch flycatchers, drongos and mudnest builders. 
The following three subspecies are widely recognised: 
- R. leucophrys leucophrys, the nominate subspecies, is the most widely distributed form found in Australia. The description below refers to it. There is negligible variation within this form, and little between the three all have very similar plumage. 
- R. leucophrys picata was described by John Gould in 1848.  It is found across northern Australia, from northern Western Australia to Queensland. It has shorter wings, and it has a gradient in wing length between latitudes 18–22°S across the Australian continent where this subspecies intergrades with leucophrys.  The subspecific epithet is Latinpǐcata "smeared with pitch". 
- R. leucophrys melaleuca was described by French naturalists Jean René Constant Quoy and Joseph Paul Gaimard in 1830.  It occurs in eastern Indonesia, New Guinea, the Solomon Islands and the Bismarck Archipelago. It is significantly larger, with longer bristles and larger bill.  Its subspecific name is derived from the Ancient Greek melas "black", and leukos "white". 
An adult willie wagtail is between 19 and 21.5 cm (7.5 and 8.5 in) in length and weighs 17–24 g (0.6–0.85 oz), with a tail 10–11 cm (approx 4 in) long. The short, slender bill measures 1.64–1.93 cm (around 0.75 in),  and is tipped with a small hook.  This species has longer legs than other fantails, which may be an adaptation to foraging on the ground.  The male and female have similar plumage the head, throat, upper breast, wings, upperparts, and tail are all black, with a white eyebrow, "whiskers" and underparts. The bill and legs are black and the iris dark brown. Immature birds in their first year after moulting from juvenile plumage may have pale tips in their wings,  while juvenile birds themselves have duller plumage, their upperparts brown-tinged with some pale brown scallops on the head and breast. 
The wagtail is very "chatty" and has a number of distinct vocalisations. Its most-recognised sound is its alarm call which is a rapid chit-chit-chit-chit, although it has more melodious sounds in its repertoire. The alarm call is sounded to warn off potential rivals and threats from its territory and also seems to serve as a signal to its mate when a potential threat is in the area. John Gould reported that it sounded like a child's rattle or "small cog-wheels of a steam mill".  In his book What Bird is That? (1935), Neville Cayley writes that it has "a pleasant call resembling sweet pretty little creature, frequently uttered during the day or night, especially on moonlight nights". 
Widespread and abundant, the willie wagtail is found across most of Australia and New Guinea, the Solomon Islands, the Bismarck Archipelago, and eastern Indonesia. It is sedentary across most of Australia, though some areas have recorded seasonal movements it is an autumn and winter visitor to northeastern New South Wales and southeast Queensland, as well as the Gulf Country and parts of Cape York Peninsula in the far north. It is a vagrant to Tasmania,  and on occasion reaches Lord Howe Island.  There is one record from Mangere Island in the Chatham Islands archipelago east of New Zealand in 2002.  The willie wagtail was released in Hawaii around 1922 to control insects on livestock, but the introduction was unsuccessful and the last sighting was at Koko Head in 1937. 
The willie wagtail is at home in a wide variety of habitats, but avoids densely forested areas such as rainforest. It prefers semi-open woodland or grassland with scattered trees,  often near wetlands or bodies of water.  In New Guinea, it inhabits man-made clearings and grasslands, as well as open forest and mangroves.  On Guadalcanal, it was reported from open areas and coconut groves.  It has responded well to human alteration of the landscape and can often be seen hunting in open, grassed areas such as lawns, gardens, parkland, and sporting grounds.  The species spread into the Western Australian Wheatbelt after the original vegetation had been cleared for agriculture. 
The willie wagtail is almost always on the move and rarely still for more than a few moments during daylight hours. Even while perching it will flick its tail from side to side, twisting about looking for prey. Birds are mostly encountered singly or in pairs,  although they may gather in small flocks.  Unlike other fantails, much of its time is spent on the ground.  It beats its wings deeply in flight, interspersed with a swift flying dip. It characteristically wags its tail upon landing after a short dipping flight. 
The willie wagtail is highly territorial and can be quite fearless in defence of its territory it will harry not only small birds but also much larger species such as the Australian magpie (Gymnorhina tibicen), raven (Corvus coronoides), laughing kookaburra (Dacelo novaeguineae), and wedge-tailed eagle (Aquila audax).  It may even attack domestic dogs, cats and humans which approach its nest too closely. It has also been observed harassing snake-neck turtles and tiger snakes in Western Australia. When harassing an opponent, the willie wagtail avoids the head and aims for the rear.  Both the male and female may engage in this behaviour, and generally more intensely in the breeding season. Territories range from 1–3 ha (2.5–7.4 acres) in area.  A pair of birds will declare and defend their territory against other pairs in a diving display. One bird remains still while the other loops and dives repeatedly before the roles are reversed both sing all the while. 
The bird's white eyebrows become flared and more prominent in an aggressive display, and settled and more hidden when in a submissive or appeasement display. 
Willie wagtails usually pair for life. The breeding season lasts from July to December, more often occurring after rain in drier regions. Anywhere up to four broods may be raised during this time. It builds a cup-like nest on a tree branch away from leaves or cover, less than 5 m (16 ft) above the ground. Rafters and eaves may also be used. It has been observed to build its nest in the vicinity of those of the magpie-lark (Grallina cyanoleuca), possibly taking advantage of the latter bird's territoriality and aggression toward intruders. Similarly, it is not afraid to build near human habitation. 
The nest consists of grass stems, strips of bark, and other fibrous material which is bound and woven together with spider web. Even hair from pet dogs and cats may be used.  It has also been observed attempting to take hair from a pet goat. An alpaca breeder in the Mudgee District of New South Wales has observed alpaca fleece in the nests of willy wagtails (the results of scraps of fleece not picked up at shearing time). The female lays two to four small cream-white eggs with brownish markings measuring 16 mm × 21 mm (0.63 in × 0.83 in),  and incubates them for 14 days.  Like all passerines, the chicks are altricial and nidicolous they are born naked and helpless with closed eyes, and remain in the nest.  Both parents take part in feeding the young,   and may continue to do so while embarking on another brood.  Nestlings remain in the nest for around 14 days before fledging.  Upon leaving, the fledglings will remain hidden in cover nearby for one or two days before venturing further afield, up to 20 m (66 ft) away by the third day. Parents will stop feeding their fledglings near the end of the second week, as the young birds increasingly forage for themselves, and soon afterwards drive them out of the territory. 
The female pallid cuckoo (Cuculus pallidus) will lay eggs in a willie wagtail nest, although the hosts often recognise and eject the foreign eggs, so successful brood parasitism is rare.  Parasitism by the fan-tailed (Cacomantis flabelliformis), brush, (C. variolosus), Horsfield's bronze (Chrysococcyx basalis), and shining bronze cuckoo (C. lucidus) has also been reported. 
Although the willie wagtail is an aggressive defender of its nest, predators do account for many eggs and young. About two thirds of eggs hatch successfully, and a third leave the nest as fledglings. Nestlings may be preyed upon by both pied butcherbirds, (Cracticus nigrogularis) black butcherbirds (C. quoyi), the spangled drongo (Dicrurus bracteatus), and the pied currawong (Strepera graculina), as well as the feral cat (Felis catus), and rat species. The proximity of nesting to human habitation has also left nests open to destruction by children.  Mostly male willie wagtails sing at night only during breeding season.The song rate increases with lunar illumination.  
The willie wagtail perches on low branches, fences, posts, and the like, watching for insects and other small invertebrates in the air or on the ground. It usually hunts by hawking flying insects such as gnats, flies, and small moths, but will occasionally glean from the ground. It will often hop along the ground and flit behind people and animals, such as cattle, sheep or horses, as they walk over grassed areas, to catch any creatures disturbed by their passing.  It wags its tail in a horizontal fashion while foraging in this manner the exact purpose of this behaviour is unknown but is thought to help flush out insects hidden in vegetation and hence make them easier to catch.  The willie wagtail takes ticks from the skin of grazing animals such as cattle or pigs, even from lions asleep in a zoo.  It kills its prey by bashing it against a hard surface, or holding it and pulling off the wings before extracting the edible insides. 
The adaptability and opportunistic diet of the willie wagtail have probably assisted it in adapting to human habitation it eats a wide variety of arthropods, including butterflies, moths, flies, beetles, dragonflies, bugs, spiders, centipedes, and millipedes,  and has been recorded killing small lizards such as skinks and geckos in a study in Madang on Papua New Guinea's north coast.  The tailbones of these lizards have been found in their faeces although it is unclear whether the whole animal was eaten or merely the tail. Either way, lizards are only a very occasional prey item forming between 1 and 3% of the total diet.  Evidence from the study in Madang suggested that the willie wagtail selectively fed nestlings larger prey. 
The willie wagtail was a feature in Australian Aboriginal folklore.  Aboriginal tribes in parts of southeastern Australia, such as the Ngarrindjeri of the Lower Murray River, and the Narrunga People of the Yorke Peninsula,  regard the willie wagtail as the bearer of bad news.  It was thought that the willie wagtail could steal a person's secrets while lingering around camps eavesdropping, so women would be tight-lipped in the presence of the bird.   The people of the Kimberley held a similar belief that it would inform the spirit of the recently departed if living relatives spoke badly of them. They also venerated the willie wagtail as the most intelligent of all animals.  Its cleverness is also seen in a Tinputz tale of Bougainville Island, where Singsing Tongereng (Willie Wagtail) wins a contest among all birds to see who can fly the highest, by riding on the back of the eagle.  However, the Kunwinjku in western Arnhem Land took a dimmer view and regarded it as a liar and a tattletale.  The willie wagtail was held to have stolen fire and tried to extinguish it in the sea in a dreaming story of the Yindjibarndi people of the central and western Pilbara, and was able to send a strong wind if frightened.  In the Noongar language dialects, the willie wagtail is known as the Djiti-Djiti (pronounced Chitti-chitti) and the Willaring in the Perth region. 
The Kalam people of New Guinea highlands called it konmayd, and deemed it a good bird if it came and chattered when a new garden was tilled, then there would be good crops. It is said to be taking care of pigs if it is darting and calling around them. It may also be the manifestation of the ghost of paternal relatives to the Kalam.  Called the kuritoro bird in New Guinea's eastern highlands, its appearance was significant in the mourning ceremony by a widow for her dead husband. She would offer him banana flowers the presence of the bird singing nearby would confirm that the dead man's soul had taken the offering. 
A tale from the Kieta district of Bougainville Island relates that a maneka, the willie wagtail, darting along a river bank echoes a legendary daughter looking for her mother who drowned trying to cross a flooding river in a storm.  The bird has been depicted on postage stamps in Palau and the Solomon Islands,  and has also appeared as a character in Australian children's literature, such as Dot and the Kangaroo (1899),  Blinky Bill Grows Up (1935),  and Willie Wagtail and Other Tales (1929). 
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Cited texts Edit
- Boles, Walter E. (1988). The Robins and Flycatchers of Australia. North Ryde, NSW: Angus & Robertson. ISBN978-0-207-15400-3 .
- Coates, Brian J. (1990). The Birds of Papua New Guinea, Including the Bismarck Archipelago and Bougainville. Vol. 2: Passerines. Alderley, Qld.: Dove. ISBN978-0-9590257-1-2 .
- Hadden, Don (2004). Birds and Bird Lore of Bougainville and the North Solomons. Alderley, Qld: Dove Publications. ISBN0-9590257-5-8 .
- Higgins, Peter Jeffrey John M. Peter S. J. Cowling, eds. (2006). Handbook of Australian, New Zealand and Antarctic Birds. Vol. 7: Boatbill to Starlings. Melbourne: Oxford University Press. ISBN978-0-19-553996-7 .
60 ms 4.8% dataWrapper 40 ms 3.2% assert 40 ms 3.2% validateData 40 ms 3.2% Scribunto_LuaSandboxCallback::getExpandedArgument 40 ms 3.2% type 40 ms 3.2% [others] 240 ms 19.4% Number of Wikibase entities loaded: 17/400 -->
What species of eagle pushes their young to teach them flying? - Biology
Exactly how birds acquired the ability to fly has baffled scientists for years. Archaeopteryx provided a starting point for speculation. Built like a dinosaur, but with wings, scientists guessed at how a hypothetical ancestor might have taken flight. Some scientists support the arboreal hypothesis (e.g., Feduccia 1996) and suggest that the ancestors of Archaeopteryx lived in trees and glided into flapping flight (Figure to the right). But others argue that the claws of Archaeopteryx weren't suited to climbing. So, others support the cursorial hypothesis (e.g., Burgers and Chiappe 1999) and suggest that these ancestors used their long, powerful legs to run fast with their arms outstretched, and were at some point lifted up by air currents and carried into flapping flight (Figure to the bottom right).
Studying living animals can throw light on their evolutionary past. Ken Dial (2003) of the Flight Lab at the University of Montana noticed the ability of gamebird chicks to escape danger by scrambling up vertical surfaces. The chicks first run very fast, flapping their immature, partially feathered wings, frantically creating enough momentum to run up a vertical surface to safety. Could this survival instinct be the origin of flight?
And finally, James Carey, a UC Davis demographer and ecologist, has proposed that the evolution of bird flight is linked to parental care (Carey and Adams 2001).
Whatever the origins, dinosaurs, and birds, eventually took to the air.
Dinosaurs' flapping led to flight? - The feathered forelimbs of small, two-legged dinosaurs may have helped them run up hills or other inclines to escape predators. This half running, half flapping may have evolved into an ability to fly. Dial (2003) reported findings suggesting that the ability to fly evolved gradually. Feathers may have first protected animals from cold & wet weather, then been used out of necessity when something with big teeth was chasing them. Even before their wings develop enough to fly, some living birds use them to improve traction and gain speed. Dial studied birds, like partridges, capable of only limited flight. Energetically, "It's a lot cheaper to run than fly," Dial said. So these baby birds, with big feet & powerful legs, use them in combination with their wings, first to stay balanced & grounded, then to take on steeper and steeper inclines. Using this "wing assisted incline running," Chukar Partridges can negotiate 50 degree inclines right after hatching, 60 degree slopes at 4 days old, and at 20 days, can perform a vertical ascent. "The wings help them stick to the ground," said Dial. The wings only come into play on steep angles because at about a 50 - 60 degree incline the birds start slipping. Then they begin a head to tail movement, like a reptile, that pushes them to the ground to enhance traction. "They use their wings like spoilers on a race car, to give their feet better traction," he said. Use of this wing-assisted running doesn't stop when the birds are old enough to fly. Adult birds often choose the running and flapping option instead of flying because it is more energy efficient. - Written by Marsha Walton, CNN
Flight requires lift, which results when an air stream passing over wing must travel further (and faster) than the air stream passing under a wing. The slower moving air under the wing 'pushes' against the bottom of the wing with greater force than the faster moving air above the wing & this generates lift. The lift generated is influenced by a bird's velocity (See http://www.grc.nasa.gov/WWW/K-12/airplane/vel.html).
Why does the slower moving air generate more pressure against the wing than the faster moving air? In calm air, the molecules are moving randomly in all directions. However, when air begins to move, most (but not all) molecules are moving in the same direction. The faster the air moves, the greater the number of air molecules moving in the same direction. So, air moving a bit slower will have more molecules moving in other directions. In the case of a wing, because air under the wing is moving a bit slower than air over the wing, more air molecules will be striking the bottom of the wing than will be striking the top of the wing. This is called the Bernoulli effect & this creates lift!
Wings also provide lift through Newton's Third Law of Motion which states that for every action there is an equal and
opposite reaction. As the wing moves though the air, the lower surface of the wing deflects some of the air downward. As
Newton's Third Law of Motion explains, an additional force is generated. The deflected airflow underneath the wing is the action. The reaction is that the wing moves in the opposite direction (in this case, upwards). This means that the development of low pressure above the wing (Bernoulli's Principle) and the wing's reaction to the deflected air underneath it (Newton's third Law) both contribute to the total lift force generated.
When the curvature over the top becomes greater by increasing the angle of attack (below), the air moves even faster over the top of the wing and more lift is generated. Eventually, however, if the angle of attack becomes too great, the flow separates off the wing and less lift is generated. The result is stalling. For birds, the optimum angle of attack is typically about 3 - 5 degrees. Birds also tend to stall at low speeds because slower moving air may not move smoothly over the wing.
If the angle of attack is too great, air flow over the top of the wing may become more turbulent & the result is less lift.
At low speeds (such as during take-off & landing), birds can maintain smooth air flow over the wing (and, therefore, maintain lift) by using the alula (also called the bastard wing). The alula is formed by feathers (usually 3 or 4) attached to the first digit.
When these feathers are elevated (above right & below right), they keep air moving smoothly over the wing & help a bird maintain lift.
Archaeopteryx probably flapped and glided, but did not have an alula. Eoalulavis provides evidence that by 30 million years after Archaeopteryx, at least one group of early birds had developed the alula.
- The long (or soaring) wings of birds with very high aspect ratios, like albatrosses, generate lots of lift, while the narrow, pointed shape helps reduce drag while gliding (because the small area of the pointed tip minimizes pressure differences and, therefore, turbulence at the wing tip).
- High speed wings, like those of falcons, swallows, & swifts, have relatively high aspect ratios. These narrow, tapering wings can be flapped rapidly to generate lots of speed with minimal drag (because, again, the small area of the pointed tip minimizes pressure differences and turbulence at the wing tip).
Palleroni et al. (2005) observed more than 1,800 falcon attacks on wild pigeons over seven years. They recorded the plumage types among the pigeons and noticed that while birds with white rump patches made up 20% of the pigeon population, very few were captured by the falcons. When a Peregrine Falcon attacks a pigeon, it plunges at speeds greater than 200 miles an hour, levels off and comes upon the pigeon from behind, punching it with what amounts to a closed fist. At those speeds even a grazing blow kills the pigeon the falcon then circles back and picks it up. The only way the slower-flying pigeon can escape is by dipping a wing, rolling and veering off. If the falcon is distracted by the white patch, it won't notice the dipping of the wing (which, being blue-gray, blends with the landscape) until it's too late.
- High-lift wings have lower aspect ratios & there are spaces between the feathers at the end of the wing. These 'slots' help reduce drag at slow speeds because the separated tip feathers (shown in the White Stork pictured below) act as 'winglets' and spread vorticity both horizontally and vertically.
- Wings with low aspect ratios (elliptical wings), like those of many songbirds, woodpeckers, pheasants, & quail, permit sharp turns while flying among trees & shrubs.
Another important factor that influences a bird's flying ability is wing loading - the weight (or mass) of a bird divided by wing area (grams/total wing area in square centimeters). Birds with low wing loading need less power to sustain flight. Birds considered to be the 'best' flyers, such as swallows & swifts, have lower wing loading values than other birds.
Species or group Wing-loading Swallows 0.15 Passerines 0.2 - 0.4 Hawks 0.3 - 0.5 Waterfowl 0.8 - 1.0 Pied-billed Grebe 1.2 Loons 1.4 The Flight Strategy of Magnificent Frigatebirds -- Frigatebirds cannot land on the sea because their feathers are not waterproof. If they did land, they would find it even harder to take off again because their legs are too short. Despite this, frigatebirds are perfectly suited for an aerial life over the sea because they have the lowest wing-loading (large wing area & low body mass) of any bird. Weimerskirch et al. (2003) investigated the movements of Magnificent Frigatebirds (Fregata magnificens) while foraging at sea off the coast of French Guiana. Because they are very light in comparison to their wing surface, frigatebirds can glide at altitudes of up to 2,500 meters. Then they glide downward, taking advantage of the next current. This flight strategy, which limits the bird's physical efforts, is the same as that used by migratory birds during long flights over land. Migratory birds, however, avoid flying over the sea due to a lack of thermals, while frigatebirds fly over the sea. As it turns out, ascending air currents are found over the sea only in tropical regions where the waters are warm enough to create such currents on a continuous basis. Frigatebirds can therefore fly night and day using this technique. To investigate the movements of Magnificent Frigatebirds, Weimerskirch et al. (2003) fitted the birds with satellite transmitters and altimeters, which allowed them to observe that the birds only occasionally come close to the sea surface to catch prey. They catch flying fish or squid driven above the surface by underwater predators like schools of tuna or dolphins. To identify such feeding opportunities, which are very rare, requires long hours of flight at high altitudes. Frigatebirds rarely feed their young, which consequently grow very slowly. The species is, however, well-adapted: it has a low reproductive rate and parent birds care for their young for over one year, the longest period of parental care of any bird.
The high wing loading of birds like grebes, loons (check Looney Lift-Off), and swans (see Tundra Swan below) means that it's more difficult for them to generate sufficient lift to take-off. That's why these birds often run along the surface of a lake for some distance before taking flight. They must generate enough speed to generate enough lift to get their relatively heavy bodies into the air!
Want to see a Laysan Albatross taking flight?? Check this video!
L anding - Birds must usually be much more precise when landing than an airplane pilot often landing on a branch rather than a runway. During landing, birds increase the angle of attack of their wings until they stall. This decreases both speed and lift. Birds also spread and lower their tails, with the tail increasing drag & acting like a brake. Finally, legs and feet are extended for landing. Click on the Raven to the right for a cool animation . . . . (Hint: After viewing the animation, left click & hold the round cursor at the bottom you can move it and examine more carefully what's happening during landing)
Tree Swallow landing
Photo by Anupam Pal & used with his permission
The sharp leading edges of a swift's wings may create
swirls of air (gray cones) that produce extra lift
(check this Quicktime video).
Birds have two-part wings. The proximal "arm wing" is rounded on front, humped on top, and sharp on the back -- just like most airplane wings. Further away, the "hand wing" is flatter on top and extremely sharp on the front. The hand wing resembles the wing of a fighter plane, and it is also often swept back -- angled -- toward the rear. Wings on some high-performance jets can change angle to alter the leading-edge vortex. Wings that are nearly straight out create more lift. Swept-back wings create more drag (air friction). Acrobatic birds may also take advantage of the LEV changing wing angle gives them the ratio of lift and drag they need for flying and snatching insects in mid-air.
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Carey, J.R. and J. Adams. 2001. The preadaptive role of parental care in the evolution of avian flight. Archaeopteryx 19: 97 - 108.
Dial, K. P. 2003. Wing-Assisted Incline Running and the Evolution of Flight. Science 299:402-404.
Feduccia, A. 1996. The origin and evolution of birds. Yale Univ. Press, New Haven.
Hedenstrom, A. and S. Sunada. 1999. On the aerodynamics of moult gaps in birds. Journal of Experimental Biology 202:67-76.
Hedrick, T. L., B. W. Tobalske, and A. A. Biewener. 2002. Estimates of circulation and gait change based on a three-dimensional kinematic analysis of flight in cockatiels (Nymphicus hollandicus) and ringed turtle-doves (Streptopelia risoria). Journal of Experimental Biology 205:1389-1409.
Palleroni, A., C. T. Miller, M. Hauser, and P. Marler. 2005. Predation: Prey plumage adaptation against falcon attack. Nature 434:973-974.
Sanz, J. L., L. M. Chiappe, P. Perez-Moreno, A. D. Buscalioni, J. J. Moratalla, F. Ortega, & F. J. Payata-Ariza. 1996. An Early Cretaceous bird from Spain and its implications for the evolution of avian flight. Nature 382: 442-445.
Sanz, J. L. and F. Ortega. 2002. The birds from Las Hoyas. Science Progress 85:113-130.
Videler, J.J., E.J. Stamhuis, and G.D.E. Povel. 2004. Leading-edge vortex lifts swifts. Science 306:1960-1962.
Weimerskirch, H., O. Chastel, C. Barbraud, and O. Tostain. 2003. Frigatebirds ride high on thermals. Nature 421:333-334.
Watch the video: EAGLE FAMILY TRAIN THEIR YOUNG TO FLY (September 2022).