For most of the males (and the less demonstrative females), this region is just a way station on their migration from the southern Atlantic coast and Deep South. While a few woodcocks remain here for the summer to nest, most will continue north in the coming weeks, returning to their traditional breeding grounds in Maine and eastern Canada.
The woodcock is an object of concern for conservationists, who have observed a long-term decline in the species as its favorite habitat has been gobbled by development, or simply grown up into mature forests the woodcock cannot use.
But in spring, it is the male's courtship flight that attracts the most attention.
"When people see this display - these gawky birds and the sounds they make - their jaws drop open. These birds don't look like they can do what they do," said Chris Bennett, environmental educator for the Wetlands Institute in Stone Harbor, N.J.
Through most of the year, woodcocks specialize in staying out of sight. Both sexes are plump, about the size of a man's fist, and are colored almost identically - a concealing mix of brown, black and gray that blends perfectly with the background of dead leaves.
Even when danger approaches, a woodcock plays it cool, sitting tight against the ground and trusting its camouflage. A human must almost step on it before it flushes, leaping into the air with a startling twitter created by air whistling through its wing feathers, which are stiff and narrow.
Only in spring does the male woodcock make an intentional spectacle of
himself. Each evening, usually starting in early March in the Philadelphia area, they gather in small groups on traditional courtship grounds, often wet meadows near thick cover where the grass isn't too tall or overgrown.
As dusk settles, each male picks a spot, puffs himself up and makes an explosive "peent!" that sounds more like a frog or a machine than a bird. The peents continue every five or 10 seconds for a minute or so, until the male launches himself into flight - a whirring, bumblebee shape just visible against the fading red of the western horizon. The modified wing feathers make a madcap whistle as he climbs.
"It's comical, carefree - Pan with twittering pipes," said Pete Dunne, director of natural history information for the Cape May Bird Observatory.
What comes next always shocks humans who, seeing the display for the first time, assume the strain must have been too much for the poor bird. The male suddenly falters, tumbling erratically like a falling leaf; the twitter of the wings is replaced by lovely, liquid gurgle that comes from the bird's throat.
Just a few yards above the ground - and certain death - the woodcock pulls up, makes a soft landing and starts the whole amazing performance again. Each sky dance lasts only a minute or two.
Meanwhile, other males, sometimes a dozen or more, are doing the same thing within earshot, and they'll continue until full dark. They will perform again to a lesser extent at dawn, and may continue straight through the night if the moon is bright.
The male's display probably evolved from necessity, according to Greg Sipek, a biologist with the U.S. Fish and Wildlife Service who studies woodcocks at Moosehorn National Wildlife Refuge in eastern Maine, one of the species' major breeding areas.
"The woodcock is a shorebird that has forsaken the shore for the forest," Sipek said. "It's a cryptically colored bird in a cryptically colored world of leaves and trees, so (the male) has to let the ladies see and hear where he is."
The world's other species of woodcocks - one in Eurasia and four in the East Indies - perform a much simpler display known as "roding," in which the male simply flies over the forest at dusk, singing. Only the American woodcock, Sipek said, has taken courtship to such a highly ritualized level.
The trigger for the display seems to be a combination of hormones and light levels, Sipek said. Rising hormone levels (which may themselves be tied to the increasing amount of daylight in springtime) bring the males into breeding condition, while the dim light of dusk and dawn signals the woodcock to start
This doesn't explain, however, why the birds display in the concealing murk of twilight.
"One theory is that there are fewer predators then, although I've seen goshawks pick woodcock out of the air at that time of day," Sipek said. In fact, the dominant males, which do most of the displaying and mating, are actively courting death. In Sipek's study area, about half are killed by predators before the breeding season is finished.
The males must contend not only with predators, but with each other. There is a definite hierarchy on the display grounds, with dominant individuals forcing lower-ranked woodcocks to the periphery through a combination of vocal and physical challenges, Sipek said. Should the dominant male be killed, one of the subordinates is poised to take his place.
The females gather on the display grounds, watch from the brush and pick a male for mating. How they choose remains a mystery, although females usually pick dominant males displaying near good nesting cover, he said. Ironically, the quality of the courtship flight may not be important. Sipek's colleagues studied one dominant male that never flew at all. He didn't have to - females were lining up to mate with him.
Copulation ends the pair's association, for male woodcocks play no role in chick-rearing. The female lays her four eggs within a hundred yards of the singing ground, usually picking a sheltered spot on the ground amid dead leaves. Her plumage provides excellent camouflage while she incubates the clutch, but even when she flies off to feed, the blotched and speckled eggs fade to invisibility against the leaves.
Even though the woodcock breeds in every state east of the Great Plains, its core nesting range extends from the Great Lakes east to Maine and north into eastern Canada. South of that swath, nesting woodcocks occur in much smaller numbers, but over a surprisingly wide area.
For example, volunteers conducting the five-year Atlas of Breeding Birds in Pennsylvania project, a mile-by-mile census that ended in 1989, found at least a few woodcocks nesting in every county of the state, including the fringes of major metropolitan areas such as Philadelphia and Pittsburgh.
In too many areas, though, especially in southeastern Pennsylvania and Delaware, woodcock habitat has vanished under waves of human development, and the birds themselves are becoming scarcer every year.
A handful return each spring to the protected thickets of Silver Lake Nature Center in Bristol, where naturalist-director Robert Mercer looks forward to their evening performances.
"Most years we only have three or four males here, sometimes just one. I wouldn't really be surprised if we're just a stop-off for migratory birds, mostly, with just one or two resident pairs, or maybe none at all anymore," he said. It is difficult to tell which are migrants and which remain to nest.
While woodcocks winter as far north as Bucks County and southern New Jersey, most migrate much farther south in autumn, to the Carolinas, Georgia and the Gulf coast. Their return in the spring usually coincides with the thawing of the ground, which permits the woodcocks to hunt with their favorite prey, earthworms.
In the past 25 years, the sky dance of the woodcock has become increasingly rare wherever this bird is found. Less and less of the proper habitat - a mix of damp thickets of alder and dogwood, overgrown fields and open areas for springtime displays - is available for them.
"Particularly in southeastern Pennsylvania, we're losing a lot of the old, abandoned farms to commercial and housing development, and what's not being impacted by development is simply growing up into timber that the woodcock can't use," said John P. Dunn, a wildlife biologist who studies woodcocks for the Pennsylvania Game Commission.
Ironically, European settlement was probably a boon at first to the woodcock, according to John Bruggink, a federal wildlife biologist in Laurel, Md.
The virgin forest that covered much of the East would have been unsuitable for woodcocks. But as the old-growth forests were cut and replaced with a mix of small farms and thickets, woodcocks thrived. In the 19th and early 20th centuries, many of those old farms reverted to brush - perfect woodcock habitat.
Each spring, biologists in Canada and the United States fan out across the woodcock's nesting range, counting the number of singing males along preselected survey routes. The census results indicate a dwindling population even though biologists cannot provide a firm estimate on the number of these secretive birds.
"We only have spring survey data starting with 1968, but the long-term trends since then have been declining continuously at 1.3 percent a year, more so in the eastern region than the central," Bruggink said. And while there's no hard data prior to the late 1960s, it was clear that woodcocks had been declining for quite some time before that, he said.
Data from Pennsylvania echo the national trend. Based on spring surveys, woodcock numbers have dropped 26 percent in the last 16 years, Dunn said.
Although most states, Pennsylvania included, have cut back sharply on the fall hunting season for woodcocks, "many studies have shown that hunting mortality isn't the problem - habitat is the problem," Dunn said. "If you have the right habitat, you'll have the birds."
However, woodcocks are faring better in some areas. The Cape May peninsula is one of the woodcock's major wintering areas along the mid-Atlantic coast, and the birds are abundant there in winter. Some also stick around to breed.
"Woodcock are stable (in southern New Jersey)," said Pete Dunne. "I don't think we've lost as much woodcock habitat as they have in more northerly areas. We even have them nesting right in town, in front of the fire company."
IF YOU GO
* Silver Lake Nature Center in Bucks County and the Wetlands Institute in Stone Harbor, N.J., are both conducting "woodcock walks" this weekend to witness the display flight of the male woodcock.
Silver Lake's excursion is set for Friday, starting at 5 p.m. Advance registration is required; call the center at 215-785-1177. The Wetlands Institute's walk begins at 5 p.m. Saturday; call 609-368-1211 to sign up. Both centers charge a fee for their walks.