As neotropical migrants, they are ephemeral, giving us a limited time to revel in their glory. Some just pass through on their way to breeding territory farther north. Others stay for the summer to breed the next generation before returning to the tropics for winter.
The gorgeous yellow-throated warbler kicks off the seasonal fun, and is often the first warbler to arrive in the Chesapeake watershed. On March 9, a yellow-throat was spotted in Washington, DC. Like many others, Pat and I sprang at the chance to see this real harbinger of spring. (Little did we know that social distancing guidelines would be issued days later.)
East Potomac Park sits on a small peninsula south of the Jefferson Memorial. The park has a public golf course, an indoor tennis bubble and an Irish rugby club. On that early March morning, it also had a yellow-throated warbler (Setophaga dominica). With the help of other birders, we found the warbler high in the tall trees bordering the golf course parking lot off Ohio Drive.
Many birds have confounding names, but not this one. The bird sports a brilliant yellow throat and upper breast offset by its white undersides. Generally black, gray and white, the flaming yellow jumps off the bird like a beacon.
The flanks are heavily streaked with black. The face is also black, with a broad white eyebrow and white patch behind the ears.
On top, it’s a smoky gray. The wings have a pair of white bars. Most of the bird’s features are bold, but the small yellow spots in front of the eyes are tough to see; so are the white circles under the eyes.
The sexes are similar, although females and immature birds are usually a bit paler. These tiny warblers are only a little more than 5 inches long. They weigh a mere one-third of an ounce.
Yellow-throats love life in a tree’s canopy. There, they breed and feed, and males perch to sing. They rarely come down lower; be prepared to crane your neck if you hope to see one. Fortunately, in spring and through June, the males sing incessantly from dawn to dusk, making it easier to find them.
A key reason for yellow-throats to arrive first is they don’t have far to go. The eastern U.S. birds generally winter in south Florida and the Caribbean. The birds west of the Appalachian Mountains mostly winter in Mexico and parts of Central America.
There are small resident populations in south Alabama, south Georgia, north Florida and coastal South Carolina.
The breeding range is limited to the eastern United States, from New Jersey across to the Great Lakes and down through Louisiana. Typically, yellow-throats arrive in the Chesapeake region in early to mid-March. The stately loblolly pines of the Delmarva are a favorite habitat.
In the Mississippi basin, the birds are more likely to be found in sycamore bottomlands. Although some live in high elevations (above 3,000 feet) in their winter habitat, these warblers tend to avoid the peaks of the Appalachia ridge during summer.
Females start nest construction soon after they arrive at their breeding site. In southern states, these birds use Spanish moss for nesting. On the Delmarva, they use clumps of pine needles. Nests are placed among the top limbs of trees.
Only females have a brood patch. They incubate their four-egg clutches 12–13 days. Both parents feed the nestlings, which take wing on day 10.
Many yellow-throats in the South will have a second clutch in midsummer.
The species is thought to be monogamous, at least seasonally. Overall, the population is stable.
The unusually long bills of yellow-throated warblers are designed to probe deep in the crevices of bark in search of food. Those long bills are also ideal for reaching the recesses of pinecones. Arthropods, especially the larvae of moths and butterflies, constitute a dietary mainstay. Yellow-throats also eat all manner of flies and scale insects. These warblers typically forage on the top side of branches or tree trunks but can sometimes be seen hawking insects.
Interestingly, bill length varies across the bird’s breeding territory. Birds in the East, especially on the Eastern Shore, have the longest bills. In a smooth transition, bills shrink in length the farther west one goes. Ornithologists speculate that the
big pinecones of the loblolly and other firs have gradually led to birds with longer bills.
That single yellow-throat in DC is now being joined by the rest of the warblers. This year, most will be largely out of my view, as we continue our physical distancing. The lone yellow-throated warbler will have to represent all of its cousins.
Rather than mourn the loss of prime birding time, I find that my memory of that delightful, handsome bird serves as a beacon of hope.
Largely unseen, the great migration of birds to their breeding habitat is already sweeping the nation. New generations will be born.
We will get through this tough time. And next year, I’ll be excited as ever to catch the delightful treat of wood warblers brightening our days.