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Scientific name: Buteo jamaicensis
Common name: 
Red-tailed Hawk

(Information for this Species Page was compiled by Edward Lee for Biology 220W in Spring 2000 at Penn State New Kensington)

Appearance
The red-tailed hawk is one of Pennsylvania's most abundant and most recognized birds of prey. Adult red-tails are 19 to 25 inches in length and have wing spans of 46 to 58 inches. Females are slightly larger than males but both have very similar markings and colorings. There is a great deal of individual and regional variation in the shadings of the red-tail hawk's feathers. There are "light" versions, "dark" (melanistic) versions, and even "rusty" (red) versions. Most of the red-tails in Pennsylvania are light breasted and dark (brown and black) backed with a prominent, dorsally reddish tail. Immature individuals are more dully colored than adults and are more streaked. When viewed in the air the red-tail has the stocky body, broad wings and broad, rounded tail characteristic of the Buteo hawks. The underside of the red-tail is "zoned" (light colored breast with broad bands of darker colors across the belly and a light colored tail). The dorsal reddish feathers of the tail can be seen when the hawk turns and tips during soaring.

Each year red-tails undergo a complete molting of their feathers. The first molt (at one year of age that results in the setting of the adult plumage) occurs in the early spring. Subsequent molts, though, occur at less precisely timed intervals. They may be observed in the spring, in the summer or even extending into the early winter. The molt progresses in a well defined, orderly succession and never denudes or disables the bird.

Talons and Prey Capture
There are four stout, sharp talons on each of the red-tail's feet. Three of these talons project anteriorly and one projects posteriorly. The talons are opened by leg muscles pulling on a tendon that runs from the upper leg to the foot. Impact with an object (a perch or a prey item) bends the hawk's ankle and causes the talons to rapidly and reflexively close. The four sharp talons pierce the captured prey animal deeply usually puncturing one or more vital organs causing the animal's rapid death. The hawk uses its curved, hooked beak to tear the prey apart as it feeds.

 Red-tails are opportunistic predators taking whatever prey a particular ecosystem has in abundance. This "generalistic" feeding strategy is one of the reasons that red-tails are so abundant and are so widely distributed across North America. Mice are a common food as are shrews, moles and chipmunks. The large size of the red-tail also enables them to take gray squirrels, rabbits and even young woodchucks as opportunities arise. Red-tails will also eat other birds and even large insects as they become available.

Vision
The red-tail like other hawks uses its excellent vision to find and secure its prey. The red-tail's eyes are large and deep (a design that allows excellent distance vision) and are each as large as (or even slightly larger than) the bird's entire brain. The red-tail has five-times more visual sensory cells per millimeter of retina than do humans. They also have two areas of intensely concentrated visual cells (the "fovea" which are the areas of most acute vision) compared to but one foveum in humans. The red-tail, like other hawks, also have colored oils in their eyes that refract certain wavelengths of light. This refraction pattern intensifies certain colors at the expense of others. The net consequence of this light filtration is that the browns and grays of typical prey items stand out sharply against the filtered greens of grass and brush.

Red-tail hawks can be observed occupying perches overlooking hunting areas sometimes for an hour or more at a time. Capture successes from these perches can lead to regular visits and even highly predictable timing of visits to the perch sites overlooking their territories.

Reproduction
Red-tails mate in early March. It is thought that hawks that inhabit prime habitats and who are thus not forced to separate during winter drift or migration form a monogamous mating pair for life. Pre-mating courtship flights are wild and acrobatic with flight elevations of a thousand feet or more and dive speeds approaching 100 miles per hour.

Both the male and the female participate in the construction of the nest. Usually, nests are located on the edge of a forest on a horizontal tree limb close to the trunk. If trees are not available, red-tails can make their nests on cliff edges or in rock holes. Nests are large (about thirty inches in diameter) and bulky but very solidly constructed with a base of two foot long, half inch diameter sticks and a central depression four to five inches in diameter that is lined with softer material like grasses, corn shucks, grapevines etc. In the northern parts of their range (which includes Western Pennsylvania) typically three (or more) eggs are laid per clutch. In the southern sections of their continental range a clutch would consist of one or two eggs. Eggs are laid in Pennsylvania by the third week of March. They hatch after a 28 to 32 day incubation. The incubation is primarily (but not exclusively) done by the female. The male brings the female food or she may, in mild weather, leave the nest for short periods of time to hunt.

Care of the Young
Hawklets remain in the nest for six to seven weeks after hatching and require a great deal of parental care and feeding. At four weeks the hawklets can begin to feed themselves from prey items brought to the nest by the parents. By five weeks, the hawklets can tear intact prey organisms apart. At six weeks the hawklets are almost fully grown and by seven weeks begin to fledge.

After learning how to fly, the young hawks must then learn how to hunt. Their learning is primarily through trial and error and accumulated experience rather than through direct parental instruction, In fact, the parent birds ignore and typically quickly lose their often noisy young when they go out hunting. After four more weeks or so, the young birds are on their own and take on the role of active hunters.

Migration
Red-tails, like most birds, primarily migrate if food supplies become insufficient to sustain them through the winter. Hawks occupying prime feeding territories, then, tend not to migrate while hawks occupying more marginal territories must. Young red-tails tend to migrate the furthest (sometimes as far south as Panama), but migration to just south of the persisting snow cover is more typical. Sometimes migration occurs in groups but other times it may be accomplished singly.

Red-tails are rapid learners and will very quickly acquire (or reject) behaviors based on the relative hunting successes those behaviors generate. Red-tails, for example, that hunt near highways become very rapidly inured to the presence and activities of humans, cars and trucks. This familiarity can lead to their utilization of a rich feeding territory but can also have detrimental impacts on careless birds.



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