White-tailed kiteElanus leucurus, was described in 1818 by the French ornithologist Louis Jean Pierre Vieillot under the binomial name Milvus leucurus with the type locality as Paraguay. It is now one of four species in the genus Elanus which was introduced in 1809 by the French zoologist Jules-César Savigny. The word Elanus is from Ancient Greek elanos for a "kite". The specific epithet leucurus is from the Ancient Greek leukouros for "white-tailed": leukos is "white" and oura is "tail".
The coloration of the white-tailed kite is gull-like, but its shape and flight is falcon-like, with a rounded tail. Mainly white underneath, it has black wingtips and shoulders and orange-red eyes.
The white-tailed kite was rendered almost extinct in California in the 1930s and 1940s due to shooting and egg-collecting, but they are now common again. Their distribution is patchy, however. They can be found in the Central Valley and southern coastal areas, open land around Goleta including the Ellwood Mesa Open Space, marshes in Humboldt County, and also around the San Francisco Bay.
They are readily seen patrolling or hovering 80 feet off the ground over lowland scrub or grassland. Outside the breeding season, they roost communally in groups of up to 100. Wikipedia