Look quick – warblers passing through, heading south.
Published September 16, 2023, in the McAllen Monitor
Story and photos by Anita Westervelt, Texas Master Naturalist
Be on the lookout for tiny black and white birds, zipping lickety-split through the trees. Fall migration is on.
Easy to spot, difficult to photograph, the black-and-white warbler, with its striking bold stripes, is always a thrill to see. It is one of my favorite photographic challenges. The bird doesn’t stay still for a photograph. It’s a bug eater. Whether scurrying around the bark of a tree, or on the wing, its quirky maneuvers and aeronautical antics are the result of the flight and plight of erratic insects.
As a photographer, I might have a perfect shot lined up, take it and end up with a nice clear photo of tree branches – minus the bird. Or I have a black and white blur as the warbler deftly exits the photo frame – off in pursuit of its mission.
Black-and-white warblers are boldly striped in black and white. They have a black crown with bright white stripes behind each eye, two white wing-bars and spotted undertail coverts. Coverts are sets of feathers covering other feathers; they are the feathers observed when a bird is perched.
As warblers go, the black-and-white warbler is medium-sized, around five inches long. It has relatively short and heavier legs compared to other warblers and an unusually long hind toe and claw for support. Both physical attributes help with its bark-foraging habits. Its bill is longer and more curved than most warblers, allowing it to probe deep into bark crevices, searching for insects.
Some birds move downward through a tree while hunting food, others tend to move up. Black-and-white warblers move in every direction, and they’re quick. They forage on dead limbs and bark as well as hover-glean from the foliage at branch tips. They creep up and down, sideways and upside down on the bark of trees and along the branches, finding food.
As insectivores, warblers can’t be enticed to feeders with seeds. Native trees and shrubs full of insects are what help bring these birds to your yard. Their diet mainly consists of caterpillars, beetles, click and leaf beetles, ants, flies, leafhoppers, woodborers, weevils, aphids, spiders and daddy longlegs.
Like other perching birds, black-and-white warblers use dense vegetation, bushes, hedges and trees to sleep. At dusk, they fly in, grab hold of an appropriately sized twig and conk out, according to author Nicholas Lund, in an Internet column, “Wild Things.” Passerines (perching birds) have flexor tendons in their legs that involuntarily clasp shut when a bird squats on a perch. The tendons won’t relax until a bird straightens its leg, so a bird physically can’t leave until it’s ready.
Black-and-white warblers are permanent residents in Canada’s Northwest Territories, eastward and down into the eastern United States. They are nocturnal migrators. In fall, their route takes them through a wide variety of wooded habitats as they travel through to Mexico, and parts of South America. In migration and during winter, they can be found in suburban and urban parks, residential gardens, wetlands and mangroves. They are likely to be winter residents in the Rio Grande Valley and along the Gulf Coast.