Wednesday, July 9, 2008

The Shade Tree Bird

Northern orioles are common summer birds throughout much of the U.S. Not forest birds, they prefer wood margins and open woodlands with large shade trees and are thus common in older residential areas. Indeed, they once favored the stately American elms that lined our boulevards before elm blight all but eliminated those magnificent trees.

Formerly called Baltimore orioles in the Eastern U.S. and Midwest, this race is now known to interbreed with Bullock's oriole of the West and they have been classified as one species, the northern oriole. Colorful and melodious, these summer residents are known for the pendulous, sack-like nests that they weave from various plant materials; a single brood of 4-6 young are generally raised each summer and family groups may be seen at favored berry shrubs. Adults are otherwise usually found alone or in pairs, scouring trees for caterpillars and beetles.

As one might expect, the Bullock's race, a resident of drier landscapes, is best found in stands of cottonwood that line the rivers and large creeks of the Western U.S. Like their eastern counterpart, they feed on insects and fruit and are frequent visitors to chokecherry shrubs and mulberry trees. Northern orioles generally arrive in the U.S. by early May and depart for Central and South America in mid-late September.