Get ready for warblers: Pine Warblers are back on territory

 

A male Pine Warbler (Setophaga pinus) perches, quite appropriately, on a pinecone. This big White Pine (Pinus strobus) was part of his turf. I photographed this bird last Monday in Hocking County, Ohio, and the warbler was probably newly arrived and busy establishing his territory. While small numbers of Pine Warblers will overwinter in Ohio, I suspect this one wintered further south, as most do.

Pine Warblers are the first to arrive back on territory and commence singing and this one was in fine song. Of our breeding warblers - Yellow-rumped Warbler (Setophaga coronata), which commonly overwinters, is not a nester here), the Pine Warbler leads the spring parade. Before long, Louisiana Waterthrush (Parkesia motacilla) will appear very soon, then Black-and-white Warbler (Mniotilta varia), Black-throated Green Warbler (Setophaga virens), Northern Parula (Setophaga americana), and Yellow-throated Warbler (Setophaga dominica) will soon follow up. Not long after the warbler rush will be on.

I watched this Pine Warbler foraging for some time. Here, he rests among dense fascicles of pine needles. I saw him grab a few small caterpillars but was unable to photo-document them. Quite a few species of moth caterpillars specialize on feeding on pine, and a number mimic the needles to a remarkable degree. Thus, Pine Warblers employ a slow deliberate creeping style of foraging rather than the maniacal rushing about of many other warblers. Even for the sharp-eyed warbler, these pine needle caterpillars are probably pretty tough to spot and require more methodical searching.

Winter Pine Warbler

This Pine Warbler has spent the winter, thus far, at Green Lawn Cemetery on the south side of Columbus, Ohio. As fate would have it, I had a meeting only ten minutes from there yesterday, and stopped by afterwards to do some February warbler-watching in crisp mid-20's F temperatures.

Pine Warblers are second only to the Yellow-rumped Warbler in regards to winter hardiness. Virtually the entire population winters in the U.S., although the majority of birds retreat to the deep south in winter. The numbers of Pine Warblers in a Florida pine woods can be staggering. There, they often feed on seeds of native grasses, such as panic grasses in the genus Dicanthelium. So heavy is their browsing on grass seeds, from my observations, that I wonder if these warblers aren't fairly major agents of dispersal for grasses.

Columbus, Ohio, is near the northern limits of where one might have expectations of stumbling into a wintering Pine Warbler. They are not averse to capitalizing on feeders, and that's what this one was doing. It would take regular seeds, and also suet. While Pine Warblers do not apparently winter at this cemetery every year, they have in the past on a number of occasions.

In the hill country of southern/southeastern Ohio, Pine Warblers are more regular in winter. There, they frequent older stands of native Virginia Pine (Pinus virginiana) and Pitch Pine (P. rigida). As in Florida and elsewhere in the south, I have seen Ohio wintering birds working over panic grasses for seeds.

Cool as seeing the Pine Warbler was, I was primarily after a FAR scarcer winter warbler: a male Black-throated Blue Warbler. There are very few winter records in Ohio, but this fellow was found a week or so ago in Green Lawn Cemetery, and has been seen sporadically since. Try as I might, I could not locate it yesterday. Had I done so, I surely would have scoured around to try and drum up a Yellow-rumped Warbler, as surely some were about (this is our only commonly wintering warbler). That would have resulted in a three-warbler February day in Central Ohio - not something to be expected. I hear there is a Palm Warbler hanging out in Knox County, too, so at least four warbler species are in the Buckeye State.

Warbler-creepers

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.