The last week of April and the first three weeks of May are of special interest to veteran birders. During this period, warblers are streaming northward through North America; while most are heading for Canadian forests, some will settle down to breed and summer in woodlands or wetlands of the Lower 48.
Small, colorful insectivores, most warblers are active feeders, flitting among the branches of trees or shrubbery. As a result, they are often difficult to observe and identify, posing a challenge for both novice and veteran birders alike; their diversity, represented by some 55 species in North America, only adds to the confusion. Some are relatively easy to identify; black-and-white warblers forage along limbs and tree trunks in the manner of nuthatches, yellow-breasted chats often sing (or lecture) from an exposed perch, and ovenbirds and waterthrushes feed on the ground and along streams (respectively). Among the more common summer residents are yellow warblers, American redstarts, common yellowthroats, yellow-breasted chats, prairie warblers and prothonotary warblers; the latter, which nest in tree cavities, are best found in stands of bottomland timber.
As they migrate northward, warblers often congregate at areas just south or north of major bodies of water; there they may be found in large, mixed flocks and are more readily observed. Cape May, New Jersey, on the northern side of Delaware Bay, and Magee Marsh, on the south shore of Lake Erie, are two such areas; at either of these sites, a birder might observe a dozen or more warbler species on a morning or late day visit in early to mid May.
