Black-and-white Warblers are among the tide of migrating birds who flow southward through eastern North America in fall. Warblers don’t eat birdseed. They need insects. They have to go where their food is active in winter. Someplace warm, like coastal Texas or Central America.
Already in early September, the leaves in my yard are starting to thin out, so it’s easy to spot birds now. Makes up for the fact that warblers aren’t singing as they did in spring.
Down the trunk
Black-and-white Warblers habitually hunt for insects in the bark. While many other warblers search through tree leaves, this warbler spends a lot of time probing into crevices on the bark. You can often see it walking straight down the trunk head first.
Because of its unusual posture, many birders have noticed a similarity between the Black-and-white Warbler and the White-breasted Nuthatch. The two species are not close relatives, but they share a feeding strategy. That may be why both have an extra-long back talon (toe) that lets them hang on to the trunk as they walk down it.
Nuthatches, though, are not limited to eating insects and other small animal life. Because they also eat seeds, they can live all year long in Iowa and other cold places. Black-and-white Warblers never stick around for freezing weather. Where I live, they are strictly a phenomenon of fall and spring.
Sexing the warbler
It’s easy to tell apart female and male Black-throated Warblers. Females have sparse, indistinct streaks on their sides and a pale cheek. Males have bold black streaks and a strong black patch on the cheek.
Black-and-white Warblers breed in the north, east, and southeastern US. I wish they nested where I live, but they generally skip nesting in Iowa. So I have to watch them in passage, as they migrate through.
Where it lives
This map by the Cornell Lab of Ornithology shows the winter range in blue, the breeding range in orange, and yellow for the areas where the species is seen in migration. (Click the map for bigger image, or visit the Cornell Lab's Black-and-white Warbler page.)
They are a delight of the fading year. Knowing that Black-and-white Warblers will soon be gone makes it poignant for me. I’m missing them already.