Forests rise, woodcocks fall?
Daniel Dessecker has a cutting-edge proposal for nature lovers in the eastern United States. Stop hugging all those trees, he urges, and start chopping some down.
A biologist seemingly smitten with the smell of sawdust, Dessecker believes that when people fell some timber, they could be coming to the aid of a troubled group of birds--chief among them a rotund little creature named the American woodcock. Other researchers, however, urge people to think twice before brandishing their chain saws in defense of these birds.
"If small in size and done in an ecologically sensitive manner, clear-cuts can be beneficial to certain species, such as woodcocks," says Douglas Inkley, a senior scientist with the National Wildlife Federation. "But clear-cutting in large blocks or without due consideration for erosion, wildlife and stream quality, is uncalled for anywhere."
Woodcocks, which inhabit young forests across much of eastern North America, are not endangered. But biologists are worried by a steady decline in woodcock numbers. Surveys conducted in prime woodcock breeding range in the East--from Virginia to the Canadian Maritime provinces--indicate the bird's population has shrunk 52 percent since 1968. In the central United States, woodcocks have declined 39 percent.
Woodcocks are a popular game bird, and about a million are taken by hunters every year. But most woodcock watchers say that habitat loss, not hunting, is the bird's big problem. And while some of that habitat loss is of the conventional woods-into-shopping-mall kind, the bird has also been hurt by a more subtle destruction. You might say woodcocks are suffering from too much of a good thing.
"When you look at the decline throughout the East, it's obvious what's going on," says Dessecker, a wildlife biologist with the Coraopolis, Pennsylvania-based Ruffed Grouse Society, a sportsmen's group devoted to improving grouse and woodcock habitat. "Our forests in the East are maturing at very dramatic rates," says Dessecker. "But not every species of wildlife lives in mature forest. Some species require young forest."
A bird of singular design, the woodcock has large pop eyes set far back on its head--so far back that it sees better to the rear than to the front. The bird needs to keep watch for trouble from behind because it spends so much time poking its bill into mud in front of it for worms.
Some experts joke that a woodcock is merely a rearranged earthworm, so lusty is the bird's appetite for wriggling invertebrates. To help it catch worms, a woodcock comes equipped with an extra-long, flexible bill. While probing in soil, the bird keeps its bill closed until it finds a worm. Then the woodcock raises just the upper portion of the tip of its bill underground to ease it around the worm's body. Snapping its bill shut again, the woodcock tweezes its prize into daylight.
Woodcocks crave infant, scrubby forest. The little birds require dense cover of the kind provided by stands of young saplings as a shield against hungry hawks and owls. Furthermore, male woodcocks need clearings in the woods as stages for their twilight courtship flight--the spectacular "sky dance" celebrated by naturalist Aldo Leopold in his classic book, A Sand County Almanac.
Unfortunately for woodcocks, parts of the East are increasingly carpeted by maturing forest. Farmers long ago abandoned infertile New England soils for richer land in the Midwest. Their pastures have become shrublands and the shrublands have become woodlands. In the Northeast, an important woodcock breeding region, many cutover forests have grown back. The regenerated forests generally range in age from 20 to 90 years--well short of anything you could call old-growth. But often they are too old for woodcocks.
Woodcock woods are the sort that sprout in the first years after a forest fire or, in the absence of fire, after timbering operations such as clear-cuts. That sapling habitat is ephemeral. And manufacturing it is controversial. "Obviously, trying to convince the public that clear-cutting is a good idea is not in vogue right now," allows Dessecker.
But opposing clear-cutting is hardly irrational. After all, when activists ignited a 1996 campaign to ban clear-cutting in northern Maine (earning 30 percent of votes cast in a state referendum on the issue) they were reacting to decades of what they called indiscriminate timber harvesting conducted without regard for wildlife needs. In the last 15 years, Maine timber barons have cut an area roughly the size of Delaware.
Cutting down chunks of forest may help woodcocks, but it may also hurt trout and salmon, among other species. "When you clear-cut on steep slopes and fragile soil, you get erosion problems, and erosion is bad for trout," says Steve Moyer, government affairs director for Trout Unlimited, a fisheries-conservation organization. "It silts in streams and covers over spawning habitat, and smothers aquatic life that sustains trout fisheries."
For wildlife, clear-cuts may be the ultimate good-news/bad-news scenario. Consider research by John Hagan, director of conservation forestry at Massachusetts' Manomet Center for Conservation Sciences. Studying the effects of "industrial forestry" on bird populations in Maine, he has surveyed everything from virgin timber to freshly made clear-cuts.
"We were kind of surprised at the number of species that were using, in fact had their highest abundance in, clear-cuts or the scrubby growth that comes in 5 to 10 years after a clearcut," says Hagan. The birds included species of concern to conservationists, such as chestnut-sided warbler, Nashville warbler and Lincoln's sparrow.
That was the good news, says the scientist. Clear-cuts "weren't biological deserts; in fact, they were important to a lot of species," notes Hagan. "The bad news is that when you make a clear-cut it comes at the expense of mature forest, and there's another set of birds that use mature forest, and obviously they're not going to live in a clear-cut."
For biologists who manage woodcocks, clear-cuts can be a useful substitute for natural habitat disturbance. "If I was ever to go to the tropics, I would certainly never say you should clearcut," says Greg Sepik, a wildlife biologist who has studied woodcocks for about two decades at Moosehorn National Wildlife Refuge in Maine. "But in the Northeast and Michigan [important woodcock breeding range], there's a natural disturbance pattern, which has historically always been fire. And we don't have that anymore. So we have to mimic it somehow."
Sepik and his colleagues mimic fire with forestry. At Moosehorn, they have roughly tripled the woodcock population over the last 15 years by logging 5- to 10-acre blocks of woodland to stimulate growth of early successional habitat. In a study done in the late 1980s, refuge biologists used a pointing dog to locate female woodcocks on their nests. Although much of the refuge has not been logged, most woodcocks were nesting within or near regenerating clear-cuts filled with dense growth of young aspen, red maple and gray birch.
The dense stem canopy in regenerating clear-cuts does more than shield birds and their nestlings from owl attack. Shade from the canopy retards the growth of grasses and other low plants, leaving bare soil in which woodcocks more easily probe for earthworms.
Woodcocks may actually be expanding their breeding range northward in Canada's boreal forest, where timber harvesting is increasing. "We have found from survey work that the birds are readily using new cutovers," says biologist Daniel Keppie of the University of New Brunswick. Keppie says male woodcocks colonize fresh "cutovers," which mimic natural forest openings, for their courtship displays.
Those spectacular displays contribute much to woodcock mystique. At dusk and dawn in spring, a courting male visits an open area referred to as a singing ground. (It can be a gap in the forest, an abandoned farm field, even a powerline right-of-way.) Standing on the ground, he begins wooing nearby females by uttering a series of buzzy notes--the peent sound --every few seconds, rotating his body as he does so. Next, the male flies upward, spiraling higher and higher into the twilight. As he rises, air rushing through his outer wing feathers makes a whistling, twittering sound. At the peak of his ascent, wrote Aldo Leopold, the bird begins tumbling down "like a crippled plane, giving voice in a soft liquid warble that a March bluebird might envy." Landing at his take-off spot, the male woodcock soon resumes peenting, and repeats his aerobatics a dozen or more times.
For woodcock counters, the male display provides one of the only ways to record ups and downs--mostly downs--in the population size of a small bird that spends much of its time behind a privacy screen of saplings and thickets. In the woodcock singing-ground survey conducted every spring since the 1960s by the U.S. Fish and Wildlife Service, volunteers in states with major breeding populations record the number of males heard singing after sunset. Using the survey numbers to estimate changes in woodcock abundance, scientists have charted an average decline of 2.5 percent per year among eastern birds and 1.6 percent per year among birds west of the Appalachian Mountains. Unfortunately, woodcocks are but one bird being squeezed by the shortage of young forest.
"We're losing a whole set of species," says Robert Askins, a zoologist at Connecticut College. Yellow-breasted chats have essentially disappeared from southern New England, where they were once common, says Askins. Golden-winged warblers are in similar trouble throughout the Northeast. Both are what he calls "shrubland" specialists, as are other declining birds such as the brown thrasher and field sparrow. Like the woodcock, all require something other than mature forest.
There's good evidence that there were large areas of such habitat long before Europeans colonized the Eastern Seaboard, Askins says. Fires started by Mother Nature or set by Native Americans raced through woodlands. Storms blew down trees. Beavers dammed streams and created ponds; when the beavers depleted their food supply and moved on to other areas of forest, the ponds gradually turned into beaver meadows.
Scientists such as Askins say it is not difficult to create such habitat. In areas already managed to produce timber, some clear-cutting can be used to generate young growth that certain birds need. In wilderness tracts where logging is forbidden, says Askins, beavers could be reintroduced to naturally open up the landscape. Maintaining a stable shrub layer along powerline rights-of-way, by selectively killing trees, provides habitat for shrubland birds such as field sparrows and chestnut-sided warblers.
The tricky business for land management agencies is satisfying a wide spectrum of forest users, including preservationists who cringe at the whine of a chain saw and bird hunters who want to unleash spaniels and pointers in young aspen.
"It almost gets down to which forest is more morally right?'," says John Bruggink, a wildlife biologist who tracks woodcock population trends for the U.S. Fish and Wildlife Service. His answer? "Well, we need some of all kinds of forests."
Washington, D.C., journalist Michael Lipske wrote about endangered flowering plants in the December/January issue.
"Our forests in the East are maturing at very dramatic rates. But not every species of wildlife lives in mature forest."
An NWF Priority
In the Northeast, NWF is pushing for stronger limits on large-scale clear-cuts, especially "liquidation" cuts. In these cuts, loggers strip all trees from large tracts and grind them into chips. This practice impairs a forest's ability to renew itself and increases erosion. NWF and its affiliate, the Vermont Natural Resources Council, recently helped pass a bill to curb liquidation cuts in Vermont. To stay informed on eastern forest issues, write: NWF, Northeast Natural Resource Center, 58 State St., Montpelier, Vermont
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|Title Annotation:||American woodcocks flourish in young forests|
|Date:||Oct 1, 1997|
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