From the April 2010 Conservationist
Every Call Counts
Biologists use singing-ground survey to monitor woodcock populations
By Mike Murphy
Meet the American woodcock, Scolopax minor.
As a wildlife biologist, my job sometimes entails counting critters. But many species of wildlife are elusive and difficult to monitor, which can pose a problem. Sometimes, a species' behavior makes it much easier to find, which allows researchers an opportunity to gather important biological information. For instance, some species of game birds, like the woodcock, become much more noticeable during the breeding season when courtship rituals bring them out of hiding. Loud distinct calls or showy displays-such as a male ring-necked pheasant's crow, a male wild turkey's gobble, and a male woodcock's call and aerial show-give the animals away, making it much easier for biologists to count them.
Migratory birds, woodcock spend their winters in the southern U.S. and head north in early spring, following the receding snow. They arrive on the breeding grounds in mid-March, at a time when winter can be brutal and unforgiving. (They feed by probing the ground with their long bills to catch earthworms and other invertebrates, so as soon as "seeps" open in areas of melted snow, woodcock are quick to follow.) After the long journey, males quickly establish "singing grounds" in abandoned fields or other open areas where they have space to perform their fascinating courtship ritual to attract females.
At dusk, a sitting male woodcock will utter a series of nasal sounds called "peents" which sound more like the buzz of a large insect than a bird. It then takes flight upwards in a spiral hundreds of feet high, circling and singing high above the ground in a chirping flight song before descending, continuing to sing as he falls like a leaf to the ground. This acrobatic aerial display is sometimes referred to as a "sky dance." Few birds in our area rival the woodcock's fervor.
The Singing-ground survey area is shown
in dark gray; the breeding range in the
By counting the number of displaying or peenting male woodcock in an area, ornithologists found they could monitor the bird's population over time. Thus, the North American Woodcock Singing-ground Survey was born in 1968. The survey ranges from Virginia to Quebec, and is coordinated by the U.S. Fish and Wildlife Service in cooperation with the Canadian Wildlife Service and state and provincial wildlife agencies. Survey routes were established along lightly traveled roads to: minimize disturbance from vehicle traffic; provide a safe survey route for observers; and provide a quiet place to listen for peenting woodcock. New York has 100 survey routes scattered across the state.
The survey is timed to coincide with the peak of display behavior, and runs from April 20-May 10 in southern New York, and April 25-May 15 further north. For consistency, the same observer runs the same 3.6-mile route from year to year. Depending on the amount of cloud cover, the survey begins either 15 minutes (in cloudy conditions) or 22 minutes (when clear) after sunset, which is the time male woodcock call most. Run only once during the breeding season, surveys are not attempted in strong wind, in heavy precipitation, or if the temperature drops below 40 degrees Fahrenheit, as the birds are less likely to be calling or to be heard. Observers record the number of peenting males heard during a two-minute interval at each of the ten stops along their routes. Surveys must be completed in 38 minutes, and to avoid hearing the same bird twice, stops are spaced 0.4-miles apart.
Once surveyors complete their routes, data is sent to the U.S. Fish and Wildlife Service's Division of Migratory Bird Management in Laurel, Maryland. There, federal biologists analyze the data and prepare an annual report, American Woodcock, Population Status (found at www.fws.gov/migratorybirds/). Biologists use this data to create management plans for the long-term health of the woodcock population, including determining bag limits and season lengths for hunting. Over the 40+ years that the survey has been conducted, data collected indicates that New York's woodcock population has declined 42% since 1968. Despite this drop, however, woodcock are still reasonably common in early successional habitats and during the peak of fall migration.
Biologists agree that the primary reason for the woodcock's decline is the loss of their preferred early stage forest habitat. New York's forests have become mature, which is more suitable for deer, bear and turkey. Consequently, we have more deer, bear and turkey than we've had at any time in modern history, but the flip side is that we have fewer woodcock, golden-winged warblers, brown thrashers and eastern towhees, as well as other kinds of wildlife that favor early succession habitat.
Compounding this problem is that clear-cutting patches of forest land, a technique known to improve habitat for woodcock and other early succession species, is not widely accepted by the public. In fact, clear-cutting is sometimes viewed as detrimental to the environment. Yet, if done properly, clear-cutting can provide benefits for many kinds of wildlife. Today's wildlife managers face the challenge of balancing diverse public demands for wildlife and the habitat requirements of woodcock and other early succession wildlife, with those of species requiring mature forests or even large open expanses of grasslands.
In the case of woodcock, clear-cuts can be as little as ½ an acre for singing grounds and five acres or more for nesting and brood-rearing cover. Clear-cutting swaths from elevated upland areas through moist bottomlands is ideal for producing a variety of habitats. Landowners interested in seeing more woodcock and wildlife diversity should consider clear-cutting small patches as a land management option in the future.
Those who have seen a woodcock will tell you what an interesting and unusual bird it is. Its long bill, round body, large eyes, erratic flight, preference for earthworms, and intriguing courtship behavior make it unique in the bird world. Biologists and birdwatchers alike delight in hearing singing males in the spring. And while they're in pursuit of woodcock, sometimes they'll see thousands of geese headed north, hear the unmistakable call of a whip-poor-will in a far-off wood, or the nearly deafening sleigh-bell-like chorus of spring peepers in a nearby wetland.
Visit an abandoned farm field at dusk in April or May and you, too, can enjoy the sights and sounds of nature. The "little lover of bogs and swamps" is certain to entertain!
Biologist and hunting enthusiast Mike Murphy directs DEC's gamebird program from his office at the Richard E. Reynolds Game Farm in Ithaca, and is the New York State coordinator of the federal woodcock Singing-ground Survey.
To learn more about woodcock, refer to the Wildlife Management Institute's Woodcock Conservation Plan
If you'd like to manage your land for woodcock, check out A Landowner's Guide to Woodcock Management in the Northeast
For further reading, see "The American Woodcock" in the October 2006 of Conservationist.
Photo: Dave Larnerd