by John Shackford
Do you ever wonder what some of our migrant birds do during the breeding season, before they head out for Oklahoma and points south? I do, but usually I do not take the time to look it up. The Orange-crowned Warbler (Vermivora celata) is one such bird. It is one of our most common warbler migrants, and yet I know almost nothing about it during the breeding season.
The nesting range of the Orange-crowned Warbler is a broad band across most of Alaska and Canada, then along the Rocky Mountains almost as far south as Mexico. It usually nests on the ground, but one nest reported in Bent (Life Histories of North American Wood Warblers, 1953) was “in a bush 18 inches from the ground.” Nests usually have 5 eggs but sometimes 4 or 6. The eggs are white and speckled, most heavily around the larger circumference end of the egg. The nests are fairly substantial for a warbler, perhaps at least partly to effectively hold heat in the nest during incubation in cold northern latitudes.
According to Bent (1953) “(t)he main migration route is through the Mississippi Valley, northwestward in the spring and southeastward in fall. It is very rare in spring in the northern Atlantic States…but there are many fall records for this region.” So during migration, this is primarily a warbler of the central flyway, our flyway; most warblers migrate in largest numbers through the eastern U.S.
I have heard it postulated that during the last ice age, some 10,000 years ago, migratory birds that originated long ago in the tropics of central and South America spread their breeding range northward in North America as the ice retreated into Canada. It is hard to know the exact pattern of how and when a bird expands northward, but for whatever reason the Orange-crowned Warbler has a strong connection to the central U.S., including Oklahoma.
The Orange-crowned Warbler is hardy enough to sometimes show up on our Christmas Bird Counts. According to Bent (1953), “it probably eats a fair proportion of berries and other fruits, especially when it spends the winter somewhat farther north than insects are to be found in abundance.” Bent also says it will come to feeders to eat suet, peanut butter, and doughnuts. So save your stale doughnuts!
Identification of the Orange-crowned Warbler, with its fairly drab grayish-greens and –yellows, is a little tricky, but putting several small points together, it can be done. According to the National Geographic Society’s Field Guide to the Birds of North it has “yellow undertail coverts and faint, blurred streaks on sides of breast [which] separate it from the similar Tennessee Warbler.” The Migratory Bird Center, on the web, says the feature that gives the Orange-crowned Warbler its “name—the orange crown—is barely perceptible unless one sees a male puffing up his crown in an aggressive display, or blows on the crown feathers while banding a male.”
Correction for last month’s Bird of the Month, the Piping Plover. I at least gave the impression, and was thinking, that the butterfly courtship flights of the Piping Plover are mostly vertical, but then I remembered, after posting the article, that some flights at least were horizontal to the ground. A.C. Bent (Life Histories of North American Shorebirds, 1927) says that the butterfly flights are “large circles or figure 8” that are low over the beach, thus horizontal to the ground. I guess I had seen too many Mountain Plover butterfly flights, which ARE mostly vertical. Please don’t anyone hesitate to correct me when I stray!