Tuesday, April 14, 2009


While on a recent foray in Shawnee State Forest, I came across a number of individuals of three of the early-bird arrivals in the warbler world. These three – Pine Warbler, Yellow-throated Warbler, and Black-and-white Warbler – are among the first to return to Ohio, often by March’s end. Life is tougher for largely insectivorous birds that return before leaf-out. Once the foliage materializes, far more caterpillars can be found, and little wriggly larvae make the warbler world go ‘round. But these three have evolved specializing feeding niches that frees them from the need for leafy trees.

Beautiful male Pine Warbler poses briefly in a Red Maple, Acer rubrum. They are hardy; nearly the entire population winters in the U.S., and some stick it out in Ohio. A more apt name couldn’t be found: Pine Warblers and pine trees go together like apples and pie.

A mature, gnarly Pitch Pine, Pinus rigida, juts skyward. This is where I first found the warbler, along with his mate. Old pines, mostly this species along with some Yellow Pine, Pinus echinata, crest the dry ridges in Shawnee, and this is where one looks for Pine Warblers. Along with the two species below, this warbler typically forages by creeping along branches and bark. In leafless early spring, more insect prey will be found among the bark crevices than elsewhere on the tree, so exploiting bark niches is smart business.

Yellow-throated Warbler, returned from its Caribbean wintering haunts, where they often frequent palms. Our breeding subspecies, Dendroica dominica subsp. albilora, is almost completely tied to Sycamore, Platanus occidentalis. In fact, it was formerly named “Sycamore Warbler”.

A towering Sycamore. These streamside trees are where one listens for the sweet lilting doubled notes of Yellow-throated Warblers drifting down from high in the canopy. As with the other two warblers in this post, this species requires older-growth timber.

Big trees support lots of lichens on their trunks, such as this Canoparmelia caroliniana, or shield lichen. This one is a great rarity in Ohio, but we’ve got lots of abundant species. Macrolichens serve as a tremendous refugia for insects, and the Yellow-throated Warbler makes a habit of poking through them as it creeps along the bark. Another good ploy in as yet leafless habitats.

Finally, the “Pied Creeper” as it was once known. Black-and-white Warblers, although not colorful in the Munsell chart style of many warblers, are nonetheless ornate in zebralike patterning. They, too, creep along bark, aided by an extended hind claw that better enables it to creep about like a nuthatch. Its genus name, Mniotilta, means “moss-plucker”.

Black-and-white Warblers work the trunks of mature deciduous trees, and require
older timber stands. The tree above is one of the largest American Chestnuts, Castanea dentata, known in Ohio. This formerly abundant component of eastern forests was decimated by disease and now persists rarely as stump sprouts or the odd big tree. Chestnuts would have supported many a Black-and-white Warbler, but now they use other trees such as oak and tulip.

These three species of warblers, along with early returning Louisiana Waterthrushes, beat the crush of other warblers, in part because their specialized feeding styles enable them to exploit niches where food can be found. Most of the other warblers come later, following the arboreal wave of flowering and leafout of forest trees as spring rolls northward, taking advantage of the bonanza of insects that emerge with the foliage.


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