Kathy and I have a profusion of pine warblers at our bird feeders. The cute little yellow tinged birds are descending by the droves in people’s yards. We often have 15 to 20 at a time.

They come to our yard along with the annual winter congregation of American goldfinches. With all these birds in our yard, we’re doing our part to bolster the country’s flagging economy by buying tons of birdseed. Okay, maybe not tons.

The unusual thing about all this is that pine warblers, unlike American goldfinches, are insect eaters rather than seed eaters. That’s why we don’t normally see a host of pine warblers at our birdfeeders.

So, why are all the pine warblers arriving to gobble up our birdseed?

One reason is that the recent freezing weather has made insects hard to come by. The second and more interesting reason is that the little warblers of the pines can adapt their diet to the exigencies of the moment---or season.

As is typical of all wood warblers, pine warblers are insectivores. They eat invertebrate creatures in the same sense that carnivorous mammals eat the flesh of other animals. But a lack of insects doesn’t drive pine warblers to starvation. They can quickly become vegetarians of sorts.

Their dietary adaptability is what enables them to remain on their breeding grounds during the winter at least as far north as the Carolinas. Most other warblers have to migrate to the warmer climes of South America---or Southeast Texas---for the winter to be assured of an adequate diet of insects.

Also, most other warblers return to their North American breeding grounds only in the spring and summer when the insect population becomes super-abundant.

But pine warblers can stay put all year in much of their breeding range as long as they can find small fruits like yaupon berries and soft seeds like grass seeds. The ones that breed in the inclemently cold regions of the northeast United States and Canada have to migrate to places like Texas and Mexico to be assured of an option of insects, fruits, or seeds.

We figure it’s the soft, hulled sunflower seeds in our feeders that are drawing the pine warblers. The birds have thin, pointed bills that aren’t much good for cracking shells on seeds, which is why the warblers prefer ready-to-eat seed.

The suet cakes we put out also attract pine warblers because nibbling on bits of suet is not unlike crunching on a beetle. Whatever we’re doing, we seem to be keeping them fat and happy during the dearth of insects.

However, we know the birds are merely down from the pines for a few weeks to take advantage of our largess. Come spring, they’ll abandon our feeders and head back up into the tall pines.

Up in the pine trees 20 or 30 feet high, the birds will glean insects off limbs and tufts of pine needles. They’ll pick beetles from beneath tree bark and plow pine cones for bugs if not pine nuts. Occasionally, the birds will sally into the air to catch moths and gnats on the wing.

The acrobatic and energetic foraging behavior of the pine warbler captured the fancy of John James Audubon. He named the bird the “pine creeping wood-warbler” in his Birds of America, and he wrote the following description: “…it gives chase to an insect on the wing; now, it is observed spying out those more diminutive species concealed among the blossoms and leaves of the pines; again, it leaves the topmost branches of a tree…alights sideways on another, which it ascends, changing its position…at every move.”

Pine warblers are more easily heard than seen high in the pines. Their song is a musical trill that Audubon described phonetically as a trr-rr-rr-rr. It’s a sound that reverberates loudly in the spring in any neighborhood or park lined with pine trees.

The scientific name, Dendroica pinus, aptly describes the bird as a tree-dwelling pine tree bird. Its breeding range extends from the pine forests of the south to the jack and pitch pine forests of the northeast and Great Lakes. Pine warblers make their homesteads in mature pine trees of forests and urban, suburban, and rural neighborhoods.

The female bird typically builds a nest 25 to 40 feet high in a pine tree, concealing it in a bundle of pine needles and pine cones near the end of a limb. She uses spider webs and silk from caterpillars to bind together pine needles, pine bark, grasses, and weeds into a deep, open cup. She then lines the nest with soft feathers.

In Houston, pine warblers may raise as many as three broods from spring through summer. Young birds hatch from the eggs in about 10 days and fledge after another 10 days.

Though the breeding season is just weeks away, the birds are more concerned at the moment about filling their bellies with backyard birdseed than about mating. That means as the birds come down from the towering pines to eye level, we can get the best looks at them we could ever hope for.

The male pine warbler is not the most beautiful warbler among warblers---the cerulean warbler would be a contestant for that title. Yet it is a remarkably handsome bird. It has an olive-green back, prominent white wing bars, a yellowish green face, a yellow throat and breast, and black streaks on its sides. Females are similar in appearance, only duller in color.

With Houston’s abundant pine trees and surrounding pine forests, the pine warbler could be the city’s mascot bird. Might offset the image of Houston as a city of only pigeons and grackles.

Ah, and what an appropriate mascot the pine warbler would be for Houston---a bird full of vigor, ever adaptable, and reminding us always of the beauty of our evergreen pine trees.

Gary Clark and Kathy Adams Clark - NPN 134
www.kathyadamsclark.com

Gary Clark's articles appear each week in the Wonders of Nature column in the Houston Chronicle. Kathy Adams Clark is a professional nature photographer who teaches photography courses and is a member of the Board of Directors of the North American Nature Photography Association. Visit their web site at www.kathyadamsclark.com.

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