Science

Learning About Woodcock

Wildlife scientists study woodcock throughout the species’ range – from the alder swamps of Down East Maine to the aspen forests of the Great Lakes states to the cane thickets of the Gulf Coast lowlands, and many places in between.
Image
Research continually improves our understanding of woodcock natural history, breeding biology, habitat use, and migration patterns. Scientists measure how populations – local, regional, and continental – respond to managers’ decisions on where and how to create young-forest habitat. They test the effectiveness of current methods of estimating the woodcock population in North America, including the annual Singing-ground Survey (SGS), held during the woodcock's spring breeding season.

While conducting the SGS, observers drive along back roads at dusk over randomly selected routes, periodically stopping to listen for and count the number of male woodcock giving their buzzing peent calls. The resulting data are compiled and evaluated by the U.S. Fish and Wildlife Service.

Scientists also examine thousands of woodcock wings that hunters annually send to the U.S. Fish and Wildlife Service. Wing analyses indicate the ratio of young birds to adult females, which provides managers with an idea of breeding success during the past year.

Combining SGS and wing-analysis data, biologists chart population trends and make recommendations on hunting-season length and bag limits in each of the two migratory bird flyways – the Atlantic and the Central – that woodcock use during their twice-a-year migrations.

Hands-On Science

Scientists band woodcock: attach numbered, lightweight aluminum bands to the birds’ legs. Later, if a banded bird is recovered (after a hunter harvests it, or a person finds it dead following an accident or a period of snowy weather),mist net researchers will add one more bit of information to our understanding of when and where woodcock travel during their north-south wanderings. (The current management regions for woodcock - the Eastern and Central - were largely delineated by examining band-recovery data.)

In spring, biologists erect mist nets on the territories of singing male woodcock and capture birds (both males and females) that fly into and become entangled in the webbing. After nesting takes place and chicks hatch, researchers may use pointing dogs to find broods – then band or attach radio-transmitters to the young birds and to their mother.

To catch woodcock in summer, fall, and winter, scientists venture onto nocturnal roost areas and nightlight birds: shine a bright light on them, which confuses or distracts them so they can be nabbed in a long-handled net. measuring bill length(Dark, rainy nights work best.) Biologists also use mist nets to capture birds as they fly to roosting areas.

Once a woodcock is brought to hand, a scientist can determine its sex and age by examining its wing feathers. The researcher measures and records the length of the bill (longer in females) and weighs the bird (females tend to be heavier), then attaches a leg band or perhaps a radio-transmitter.

Radio-Telemetry

A modern radio-transmitter weighs about 4 grams (a penny is 2.5 grams), which is less than 3 percent of a woodcock’s body weight. The radio is glued to the skin on the bird’s back with a dab of livestock cement and further anchored with a single-loop wire harness. This backpack-type attachment system does not seem to affect a woodcock’s behavior or flight ability or make it more vulnerable to predation.

The range of a typical radio is just under 1 kilometer, and the battery-powered device will continue to transmit for about 120 days. Using a receiving unit, a biologist can follow a radio-tagged woodcock and periodically determine its location. Location data provide insight into the types and structure of vegetation that woodcock use during different seasons and weather conditions, the percentage of hens that survive the nesting period, brood mortality, dates of migration, and more.
Image
Using radio-telemetry data, managers can chart how different forest-management treatments, such as clearcutting, strip-cutting, and overstory removal, affect woodcock numbers and movement patterns. They can evaluate whether non-commercial habitat-enhancement techniques – shear-cutting alder or cutting back the shrubs using chainsaws – increase local populations. They can determine how large forest patch cuts should be, to best help woodcock. And they can discover how quickly woodcock start using an area of newly created habitat.

Science improves the cost-effectiveness of habitat management undertaken to boost woodcock numbers – management efforts that also help other wild species that share young forest with woodcock.

Key Questions

Are non-native invasive shrubs as effective as native shrubs at providing nesting cover? How far do males travel between springtime display territories and feeding habitats? How close to breeding areas should nesting and brood-rearing cover be located? Where do woodcock go during bad weather? What kinds of habitats do woodcock use during migration? These are just a few of the questions that well-designed research projects are helping to answer.

The following reports are a sampling of current research underway across the American woodcock's range. Some of the projects are conducted on demonstration areas in the different regional habitat initiatives set up to help implement the Woodcock Conservation Plan. Other projects are supported by federal and state agencies and university wildlife and biology departments.

Current Research

Eastern Management Region

Patuxent Wildlife Research Center. Scientists with the Orono, Maine, field station of the U.S. Geological Survey's Patuxent Wildlife Research Center have for more than 30 years explored woodcock ecology and population dynamics; spring, summer, and fall survival rates and habitat use; habitat change along Singing-ground Survey routes; and effects of hunting pressure on survival of woodcock in Maine, New Hampshire, Vermont, and Pennsylvania. Current research focuses on woodcock survival during the fall migration and the use of young-forest habitat that has been improved or created through different land-management practices. (Both of these research emphases depend heavily on radio-telemetry.) Contact Dan McAuley, Station Leader and Research Wildlife Biologist, U.S. Geological Survey, Northeast Research Group, 207-581-3357, dmcauley@usgs.gov. Funding: U.S. Geological Survey, U.S. Fish and Wildlife Service, National Fish and Wildlife Foundation, Wildlife Management Institute.

Lyme Adirondack Demonstration Area. On lands of Lyme Timber Company in Adirondack Park, upstate New York, biologists conduct surveys of singing male woodcock during the spring breeding period. Results show a striking increase in the number of displaying males in areas where new habitat has been created. In 2008, on 21 different routes, an average of 2.95 males were heard singing per route. In 2009, on 19 routes, an average of 3.89 males were heard singing per route. In 2010, on 18 routes, an average of 8.06 males were heard singing per route. Biologists also radio-track woodcock to see how they use the habitat areas on Lyme Adirondack lands. Eleven woodcock followed in 2009 used 22 different habitat types for day and night activities. The most frequently used habitat was stands of alders, and the second most frequently used habitat was forest stands that had been heavily cut in the recent past and typically included a dense regrowth of trees 0.5 to 6 inches in trunk diameter. Contact WMI contract biologist Brian Schofield, 518-524-5238, BSchofield@uplandforestry.com. Funding: Lyme Timber Company, New York State Department of Environmental Conservation (NYDEC), U.S. Fish and Wildlife Service, U.S. Geological Survey, Northeast Association of Fish and Wildlife Agencies, National Fish and Wildlife Foundation, Wildlife Management Institute.

Great Swamp Wildlife Management Area. Biologists with the Rhode Island Division of Fish and Wildlife and the University of Rhode Island are monitoring radio-equipped woodcock at Great Swamp WMA and two other nearby management areas. In 2008 and 2009, the researchers put radio-transmitters on 19 woodcock, 17 of which were males captured on singing grounds in spring. From dusk through dawn, the males occupied singing grounds on upland areas; as day came on, most of them flew as far as 1 mile to feeding habitats in river floodplains. Feeding habitats included pole-stage and mature forest with a thick shrub understory and high densities of earthworms. Average daytime home ranges in feeding areas were 35 acres per bird in the 2008 season and 22.3 acres per bird in the 2009 season. Over three seasons, the scientists have monitored a total of 54 woodcock. The researchers also run singing-ground survey routes and note an increase in the numbers of singing males in areas where managers have been restoring old-field and shrub-thicket habitats and using logging to create young forest. Contact Brian Tefft, Rhode Island Division of Fish and Wildlife, 401-789-0281, brian.tefft@dem.ri.gov. Other investigators include University of Rhode Island professor Scott McWilliams and Roger Masse, Ph.D. candidate in the university’s Department of Natural Resources Science. Funding: Rhode Island Division of Fish and Wildlife, Rhode Island Agricultural Experiment Station U.S. Department of Agriculture, University of Rhode Island, Wildlife Management Institute.

“Habitat Use and Survival of American Woodcock in Connecticut.” Over a three-year period, wildlife biologists monitored 98 radio-tagged woodcock in high-quality and low-quality habitats. High-quality areas included lands that had been actively managed for woodcock on a private fishing club and the Stewart B. McKinney National Wildlife Refuge; low-quality areas contained suitable woodcock habitat, but the habitat had been broken up into smaller areas by residential housing development. The survival rate for birds in low-quality habitat was 25.9 percent; in high-quality habitat it was 57.6 percent. Bite marks on radio-telemetry harnesses indicated that most predation was by mammals, probably short-tailed weasels. Core areas in high-quality habitats were characterized by having fewer tree and shrub stems larger than 3 inches in diameter; were farther from the edges of the habitat; and had a greater basal diameter area (or standing tree volume), factors that appeared to make the high-quality habitats less attractive to small mammalian predators. Contact Min Huang, Migratory Gamebird Program Leader, Connecticut Department of Environmental Protection, 860-642-6528, Min.Huang@ct.gov. Funding: Connecticut Department of Environmental Protection, Connecticut Woodcock Council, Pittman-Robertson Fund (State Wildlife Grants), Hammonassett Fishing Club, and Connecticut Endangered Species/Wildlife Income Tax Check-Off Fund.

“Agricultural Wintering Habitat as a Limiting Factor for Woodcock in the Southeast: Thirty Years of Agroecosystem Change.” Wildlife scientists are studying woodcock numbers and earthworm densities in crop fields and soils in eastern North Carolina. The project follows research conducted by North Carolina State University faculty and students in the 1970s and early 1980s. Since then, changes in farming practices – including reducing tillage and narrowing the row spacing of crops – have altered woodcock nighttime foraging habitats and likely have affected the earthworm prey base. The current study, which began in 2008, includes woodcock surveys and earthworm sampling in multiple crop types. Researchers are also tracking radio-tagged woodcock and monitoring their movements and use of different habitats. Conclusions: Woodcock use no-till soybean fields planted after corn and undisked corn fields with mowed stalks more than other crop types because of cover provided by the ridge-and-furrow topography. Earthworm densities are higher in no-till fields compared to other crop types due to reduced soil disturbance. Relocations of telemetered birds indicate that frequency of woodcock field use is low: most day and night relocations were in bottomland forest. Emily Blackman, Christopher Deperno, Nils Peterson, and Christopher Moorman (North Carolina State University, Department of Forestry and Environmental Resources, Fisheries and Wildlife Sciences). Contact Christopher Moorman, 919-515-5578, chris_moorman@ncsu.edu. Funding: U.S. Fish and Wildlife Service (Webless Migratory Game Bird Research Program), North Carolina State University.

“Relationship Between Invasive Shrubs and American Woodcock (Scolopax minor) Nest Success and Habitat Selection.” At Swatara Gap State Park, in southeastern Pennsylvania, biologists set out to determine whether invasive woody vegetation affected woodcock nest site selection and nest success. Areas of the park were once actively farmed; today many formerly cultivated fields have reverted to shrublands dominated by multiflora rose, tatarian honeysuckle, and autumn olive. In 2009 and 2010, biologists used radio telemetry and pointing dogs to locate 13 nesting woodcock. Results of the study indicated that nest success and nesting habitat selection both decreased with an increase in the percentage of invasive shrubs, particularly multiflora rose and tatarian honeysuckle, within the sampled plots. Biologists speculate that the early leaf-out and dense growth structure of the invasive shrubs may make it more difficult for nesting woodcock to detect and escape approaching predators. The researchers suggest that young-forest habitat management efforts to benefit woodcock should include attempts to control and remove non-native invasive shrubs. Eric Miller and Mark Jordan (Green Mountain College, Poultney, Vermont). Contact Eric Miller, Public Lands Habitat Section, Pennsylvania Game Commission, 717-787-9613 x 3612, homiller@state.pa.us. Funding: Wildlife for Everyone Endowment, Woodcock Limited of Pennsylvania.

Central Management Region

“Factors Affecting Detection of American Woodcock on Singing-Ground Surveys.” In 2010 wildlife scientists in Minnesota completed a third year of gathering data to evaluate the probability of detecting woodcock during the annual Singing-Ground Survey (SGS). The project examines factors such as how wind may affect observers’ ability to hear woodcock, and will try to determine the effective distance that can be surveyed from individual SGS stopping points. Stephanie Bergh (Minnesota Cooperative Fish and Wildlife Research Unit and Natural Resources Science and Management Graduate Program, University of Minnesota) and David Andersen (U.S. Geological Survey, Minnesota Cooperative Fish and Wildlife Research Unit). Contact David Andersen, 612-626-1222, dea@umn.edu. Funding: U.S. Fish and Wildlife Service (Webless Migratory Game Bird Research Program), U.S. Geological Survey, University of Minnesota.

“American Woodcock Singing-Ground Surveys in the Western Great Lakes Region: Assessment of Trends in Woodcock Counts, Forest Cover Types Along Survey Routes, and Landscape Cover Type Composition.” Data obtained from observers following Singing-Ground Survey (SGS) routes in Minnesota and Wisconsin indicate that the woodcock population has fallen for more than five decades. Interpreting such trends is difficult because of a lack of information regarding the relationship between the number of singing male woodcock and the habitat, or land-cover composition, along SGS routes. This research included analyzing high-resolution land-cover data using mathematical models. Conclusions: Woodcock counts along SGS routes reflect the amount and composition of land cover along the routes, especially the amount and juxtaposition of young forest and open space. Changes in forest land cover best explain counts of singing male woodcock between 1992 and 2005. Relative to the overall landscape, developed land was over-represented among cover types along SGS routes, and wetlands and water land-cover types were under-represented. David Andersen (U.S. Geological Survey, Minnesota Cooperative Fish and Wildlife Research Unit), Matthew Nelson (Minnesota Cooperative Fish and Wildlife Research Unit and Natural Resources Science and Management Graduate Program, University of Minnesota), and James Kelley (U.S. Fish and Wildlife Service, Division of Migratory Bird Management). Contact David Andersen, 612-626-1222, dea@umn.edu. Funding: U.S. Fish and Wildlife Service (Webless Migratory Game Bird Research Program), U.S. Geological Survey, Minnesota Department of Natural Resources, Wisconsin Department of Natural Resources, Woodcock Minnesota, University of Minnesota.

Tamarac National Wildlife Refuge. A pilot study at Tamarac National Wildlife Refuge in northern Minnesota focuses on brood survival. During the spring breeding seasons in 2009 and 2010, biologists used pointing dogs to find newly hatched woodcock and attached miniature radio-transmitters to 23 chicks. Preliminary results indicate that broods hatched earlier in the season experienced heavier mortality from predation and the effects of spring snowstorms, while later broods showed better survival rates. The biologists will continue to study nest site selection, habitat use, and brood dispersal. Contact refuge manager Wayne Brininger, 218-847-2641, Wayne_Brininger@fws.gov. Funding: Woodcock Minnesota, U.S. Fish and Wildlife Service.

“American Woodcock (Scolopax minor) Migration Chronology and Clearcut Use within Arkansas.” This study on the wintering range examines woodcock use of three forest types: new clearcuts, newly planted pine plantations, and young pine plantations, on lands owned by Potlatch Timber Corporation in central Arkansas. Data from one field season have been collected. During 2011 scientists will capture birds through night-lighting, weigh them and assess their fat stores (potential indicators of health), and age, sex, and band them. The scientists will study wintering ecology and monitor times of migration by sampling clearcuts weekly in February and March until the woodcock have departed for the northern breeding range. Although male woodcock sing and display in Arkansas, woodcock have not been found nesting there; the researchers will also look for nests on the study sites. Alexandra Locher and Andrea Long (School of Forest Resources, University of Arkansas – Monticello). Contact Alexandra Locher, 870-460-1748, felix@uamont.edu. Funding: USFWS Division of Migratory Birds, Arkansas Forest Resources Center at the University of Arkansas-Monticello.

“Assessment of Open Habitat Types Used at Night by American Woodcock on Fall Migration.” Researchers are working to document woodcock use of nocturnal open habitats on the Arkansas Delta, an important stopover area for fall-migrating birds. Woodcock occupy and forage in a variety of field habitats at night, including crop fields (harvested and unharvested), old fields, and waterfowl impoundments (which timberdoodles will use until managers flood those areas for waterfowl). The study will look at relative uses of open habitat types, age and/or sex differences in open-habitat usage, and migration chronology. At night, biologists will slowly cruise through fields in all-terrain vehicles and will use spotlights and long-handled nets to capture up to 25 woodcock per field type. The research will last through at least two field seasons. David Krementz (U.S. Geological Survey, Arkansas Cooperative Fish and Wildlife Research Unit, University of Arkansas), Richard Crossett (U.S. Fish and Wildlife Service, Central Arkansas Refuge Complex – Cache River National Wildlife Refuge). Contact David Krementz, 479-575-7560, krementz@uark.edu. Funding: U.S. Fish and Wildlife Service, U.S. Geological Survey Arkansas Cooperative Fish and Wildlife Research Unit.