Across their restricted range, White-tailed Kites prefer open country. They hunt grasslands, savanna, roadsides, and agricultural areas, and are surprisingly more regular in suburban settings than most raptors. They often form large winter roosts (dozens of birds) near optimal foraging areas. Unlike other kites, the White-tailed Kite does not hawk insects in the air; instead it feeds mainly on small mammals. In general behavior, White-tailed Kite recalls a large, white Kestrel, regularly perching on wires, hovering frequently, and pouncing on prey from low to moderate height. White-tailed Kites are generally aggressive toward other raptors, frequently tussling with raptors that wander into their breeding territory. White-tailed Kites are quite vocal on the breeding grounds and during aggressive encounters. The main call is a rising, 2-noted “seee-yrrk” also a grating, short, grrrrrr often interspersed with descending, whistled hew notes recalling Osprey; also a husky, grating krr-éerrr.
There are two subspecies of White-tailed Kite but only one, E. l. majusculus, occurs throughout its North American range. The smaller nominate E. l. leucurus occurs in South America. These forms are not likely separable in the field. White-tailed Kite was formerly considered con-specific with the Black-shouldered Kite (E. caeruleus) of Africa.
About the size of a Northern Harrier.
Have long, narrow, pointed wings.
Perched, they appear slim, delicate, and somewhat small-headed.
Flies with a dihedral, usually strong when soaring, modified when gliding.
Employ languid, harrier-like wing beats but faintly stiffer and deeper.
Hover-hunt with wings above the shoulders, and body angled at 45 degrees, usually with dangling legs. Does not ‘kite’.
They stoop with wings in a strong ‘V-shape’.
White-tailed Kites are distinctly white overall with strongly contrasting black ‘shoulders’ and dark carpal spots on underwings.
Two age classes: adult and 1st-year (juvenile).
Adults are clean white below, with plain grayish upperparts and black shoulders; male averages paler above than female, with a whiter head, but differences are marginal.
1st-fall birds have boldly scaled brownish-white upperwing coverts and backs, and a rusty wash on the breast that is gone by winter.
1st-spring birds are like adults, but with pale-fringed primary coverts, and dusky, thin sub-terminal tail band.
All White-tailed Kites have orange to orange-red eyes.
Movements poorly understood and probably not true migration, but rather extensive post-breeding dispersal events.
Wandering birds can be seen away from typical habitat at almost any time.
Most movement occurs during fall and winter, when non-breeders gather in large communal roosts, sometimes numbering 50+ birds.
Presumed California breeders arrive in Oregon and on the California Channel Islands in fall, and depart over the winter.
(Map from Cornell Lab of Ornithology's All About Birds. For dynamic distribution maps, visit the eBird website.)