Jan/Feb 2016For Wildlife Watchers: Palm Warblerby Rob Simbeck
Palm warblers can be found in brushy thickets, weedy fields, forest edges, fence rows, savannas and dune habitat.
More than once, my mother said, "I'd like to be a bird. You can fly wherever you want and you don't have to buy gas."
She was in good company. A long line of humans, from Icarus to Ronnie Van Zant, have envied birds their flight and freedom. Perception, though, is not always reality. Avian movements are circumscribed by food-gathering, mating, reproduction and the seasons. Still, the fact that they are largely conducted via flight has a primal appeal for an earthbound species such as our own.
Theirs is also a fiercely competitive world, and given predation, parasites, bad weather and the encroachment of humans, who bring dogs, cats, pesticides and development into the picture, it is a much less enviable existence. Forced to choose a time and place to be a bird, I would take fall and winter at the southern end of a migratory route. Granted, migration is no picnic, but it seems winter is as kicked back as it gets for a bird. On their breeding ranges, birds have the drain of establishing and defending a territory, laying eggs, and nurturing and defending young, with the aforementioned difficulties thrown in. The winter range certainly appears to be a better deal, with food-gathering and predator avoidance the primary tasks. Even the outfit is casual - for birds, fall and winter plumage is the equivalent of human beachwear.
For those of us who watch, envy and/or write about birds, the winter range holds lots of mysteries. One is the palm warbler, which returns each spring to a breeding range that is well out of reach of most of us.
"Little is known about the breeding biology of palm warblers," says Amy Tegeler, bird conservation Coordinator with the S.C. Department of Natural Resources, because "they nest in remote and difficult-to-access locations in the boreal forests of Canada and the northern United States."
Theirs is a world of bogs and moss-covered swamps amid pine, spruce and tamarack. Such is their remoteness that some of their natural history involves educated guesswork on the part of biologists. They arrive on their breeding grounds well before most other warblers - in New England by mid-April and northern Canada by the end of the month. About five inches long, with short tails and tiny, pointed bills, they are the size of chickadees and weigh just a third of an ounce. There are two subspecies. The eastern, or yellow, palm warbler inhabits the eastern third of the breeding range. It has a striking rufus cap, yellow eye stripe, brown-olive to gray upper parts and a bright yellow underside with breast and flank streaking. The western, or brown, palm warbler has less yellow and less colorful streaking. As with many species, the females are much drabber.
Pair formation begins soon after they arrive, with the male singing to mark territory (he will also chase intruding males) and then to attract a female with a song that has been described as "a continuous, flat-toned trill consisting of several buzzy syllables."
The female builds a cup-shaped nest, three or four inches across, on or near the ground, often in sphagnum moss amid dense cover. She weaves it with sticks, weed stalks and grasses and lines it with fine grass and sometimes feathers, then lays four to five creamy white, brown-blotched eggs.
The male feeds her during the twelve to thirteen days she incubates them and both feed the young once they hatch - their diet consists primarily of insects gleaned from the ground or low foliage. The young grow quickly, leaving the nest just eight to twelve days after hatching and can fly in another day or two, although they stay with the adults for another week after fledging.
In South Carolina, westerns will outnumber the yellows, which tend to winter farther west, to as far as Texas (a small band of the westerns also winters on the Pacific Coast). "It's a little more challenging to tell them apart in winter," says Tegeler. "Both subspecies are more drab and the chestnut cap is often lacking. The yellow on the yellow subspecies' throat, breast, belly and undertail is less pronounced than in breeding plumage. The western palm warblers have a whitish or slightly yellow breast and belly with a contrasting yellow undertail."
During winter and migration, she adds, "Palm warblers can be found in early successional habitats such as brushy thickets, weedy fields, forest edges, fence rows, savannas and dune habitat." They'll often be found on or near the ground, poking through weedy pockets looking for berries as well as insects. They may be in flocks with yellow-rumped warblers, kinglets and sparrows.
The westerns reach South Carolina in early September, just ahead of the yellows, part of a migration that takes some palm warblers as far south as Central America. Their arrival can be dramatic.
"I remember a fall day birding in Huntington Beach State Park," recalls DNR wildlife technician Lex Glover, "and while walking along the dunes, I saw a few hundred palm warblers migrating south. They appeared to have flown across the inlet and were heading for the closest wax myrtle bushes and trees."
"They can be found at most major birding spots in the state," he adds, "in proper habitat, including Huntington Beach State Park, the ACE Basin, Savannah NWR and Santee NWR."
Palm warblers are among seven warbler species resident here in fall and winter, with the orange-crowned, pine, palm, black and white, and yellow-rumped fairly common and the yellow-throated and prairie less common. A major help in identifying the palm warbler - both subspecies - is that it bobs its tail almost constantly. Palm warblers are, says Tegeler, "fairly common and conspicuous during winter and during migration." The spring and summer warbler-watcher has a much brighter canvas, with twenty warbler species recorded here. As many of those species return from Central or South America, though, the palm warbler is again headed north.
On summer and winter grounds, they are susceptible to the kinds of maladies and dangers discussed above. Garter snakes, weasels and gray jays all act as predators, as do merlins and sharp-shinned and Cooper's hawks. And, like many other birds, palm warblers sometimes fly into TV towers, windmills and other structures. They are susceptible to ticks, mites and louse flies as well.
Still, their numbers seem stable, at least on their winter grounds, where it's possible to study them more closely. Their remoteness while breeding is no doubt a help when it comes to their numbers, as are the plentiful pastures, weedy fields and beaches here in South Carolina. That's good news for wildlife watchers; laid-back winter plumage notwithstanding, these are birds worth paying attention to.
Palm Warbler - Setophaga palmarum
Description: Five inches long, olive brown to grayish above, yellow to whitish underparts, yellow under tail, brown breast and flank streaking.
Range and Habitat: Breeds far northeastern U.S. and across Canada. Winters Atlantic and Gulf coasts, to Central America.
Mating: Nests on or near the ground. Lays up to five creamy-white, brown-blotched eggs.
Viewing Tips: Most major birding spots in the state, in proper habitat, including Huntington Beach State Park, the ACE Basin, Savannah National Wildlife Refuge or the Santee National Wildlife Refuge.