The White-tailed Kite usually cruises at 60 to 200 feet (19 to 62 meters) above the ground, with slow wing beats. The rate and depth of wing beats vary according to aerial conditions. Hunting and courtship flight patterns are described below. When perching into a breeze, an incoming kite approaches gracefully with legs extended. It may make contact, but be blown clear of the perch once or twice before settling as if weightless. During the breeding season, when the male provisions his mate, talon to talon in-flight transfers can take place. The two fly side by side into the wind and the female closes on the male, reaches over and takes the prey from him.
The White-tailed Kite hunts over open ground where winds aid it in hovering and soaring. A typical hovering height is about 90 feet (28 meters). The bird dangles its legs during hovering. Upon spotting prey the bird may drop to about 9 feet (3 meters) and briefly hover again before striking. The kite generally strikes feet first, but sometimes seizes the prey in its beak first. The wings are upheld during the strike. The kite will also perch hunt, which is more energy efficient but generally less successful than hovering. Hunting strategies may vary locally depending upon prey species and density, cover type and perch availability. The kite hunts most frequently in the early morning and in the late afternoon-evening. Hunting success appears to be quite high in American studies, a plausible explanation why White-tailed Kites spend the mid day perching and preening. Even when burdened with feeding females at the nests, males hunted only 12 to 15 percent of their time in one California study. A kite needs to eat roughly three voles a day, or the equivalent in other prey.
It is likely that at least some breeding pairs maintain their pair bond beyond the breeding season. However, most kites usually leave their territories after breeding, hunt alone and roost at night communally. Kites gather at a roost between sunset and dark, and after some aerial activity disappear into the foliage of the grove. Kites depart early in the morning. Roosting sites are often changed one or two times a winter. Numbers build during late fall and decline after mid-January. Territories apparently contain the foraging grounds as well and are defended against other kites. In one study, territory size varied from 7.3 to 21 acres (17.8 to 51 hectares). Two to three pairs of kites may nest fairly close together in areas of high prey density.
The White-tailed Kite commonly soars above, and swoops down, upon buteo hawks, causing them to move on. Apparently, kites do not attack Turkey Vultures but will go after other birds of prey. In California, the American Crow has been seen scavenging and robbing White-tailed Kites of their food. In Arizona, a wide variety of songbirds including Northern Mockingbird, Loggerhead Shrike, Ash-throated Flycatcher, Northern (Bullock's) Oriole, House Sparrow, Cassin's Kingbird, and Western Kingbird will nest in the same grove as a pair of kites. However, the kingbirds will harass and chase the kites persistently.
White-tailed Kites begin to form pairs in January while still roosting communally. The male establishes a territory and performs the "wings-up" display when a female is near. He holds his wings up in a V, and rapidly vibrates as he gives a continuous chittering vocalization. He may fetch a mouse to the perched female. The two birds may fly together, the male dangling the mouse to the female below who snatches it from him. Two birds perched or foraging next to each other means that pair formation is complete. The pair may also High-Soar over their territory. Copulation occurs at the male's perch with both birds calling continuously.
The life span of the White-tailed Kite is poorly known. Based on less than 100 returns from banded birds, it is known that this species lives at least five years and 11 months in the wild. Reasons for mortality are also poorly known, although in the early parts of the twentieth century shooting was responsible for much of the mortality, especially around communal roosts. The species almost disappeared from California where overgrazing virtually eliminated rodent populations which the kite depended upon. Under such circumstances, starvation must have caused the deaths of many birds.
ADAPTATIONS
The White-tailed Kite has shown a remarkable ability to adapt to changes in its habitat as long as a prey base of diurnally active rodents is available.
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Hunts rodents over open ground
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