Greg F. Sepik | Geology Reports

USGS2005

Effects of hunting on survival of American woodcock in the Northeast

Numbers of American woodcock ( Scolopax minor ) males counted on the annual singing ground survey (SGS) have declined over the last 35 years at an average rate of 2.3% per year in the Eastern Region and 1.8% per year in the Central Region. Although hunting was not thought to be a cause of these declines, mortality caused by hunters can be controlled. Furthermore, there has been no research on effects of hunting mortality on woodcock populations at local and regional levels on the breeding grounds. We used radiotelemetry to determine survival rates and causes of mortality for 913 woodcock captured during fall 1997–2000 on 7 areas in Maine, New Hampshire, Pennsylvania, and Vermont, USA. Three of 7 sites were closed to hunting. For all sites and all years combined, 176 woodcock died, and 130 were censored, of which 39 were censored mortalities. Predation was the major ( n = 134, 76%) cause of mortality. Mammals accounted for 56% of the predation, raptors accounted for 25%, and 19% was attributed to unknown predators. On hunted sites, 36% of the total mortality ( n = 102) was caused by hunting, 63% by predation, and 1 bird starved. Kaplan-Meier survival curves did not differ between hunted and non-hunted sites among years ( P = 0.46). Overall, point estimates of survival did not differ ( P = 0.217) between hunted (SR = 0.636, SE = 0.04) and nonhunted sites (SR = 0.661, SE = 0.08). We modeled hazard rates from hunting and natural mortality events using program MARK. Akaike's Information Criterion supported using a model with common constant hazards from both hunting and natural causes for groups of sites. Groupings of sites for hazard rates from natural causes were not influenced by whether a site was hunted or not. Models detected no effects of woodcock age and sex ( P = 0.52) on survival. Proportional hazards models comparing hunted and nonhunted sites found no effects of age and sex ( P = 0.45), interactions of age, sex, capture weight, and bill length ( P ≥ 0.269). Our data suggest that current hunting regulations are not causing lower survival of woodcock.

Maine, New Hampshire, Pennsylvania, Vermont↗

USGS1996

Habitat characteristics of American woodcock nest sites on a managed area in Maine

We measured characteristics of habitat near 89 nests of American woodcock ( Scolopax minor ) and 100 randomly selected points on Moosehorn National Wildlife Refuge, Calais, Maine, an area managed for woodcock. At nest sites, basal area was lower ( P < 0.001), densities of deciduous saplings were greater ( P < 0.001), densities of coniferous saplings were lower ( P = 0.001), densities of shrub stems were greater ( P = 0.002), and height of trees was shorter ( P = 0.001) than at random sites. Nest sites were closer to openings ( P < 0.001) than were random sites. Nests were in 15 cover types. The aspen ( Populus spp.), tamarack ( Larix laricina ), and alder ( Alnus rugosa ) types were used as nest sites more often than expected in relation to habitat types available at random sites ( P < 0.001). Fifty-eight percent ( n = 89) of nests were in stands of aspen, 11% in alder or tamarack, and 10% in mature second-growth gray birch ( Betula populifolia ) and red maple ( Acer rubrum ). Forty-four percent (n = 89) of the nests were in clearcuts <10 years old. Habitat characteristics around sites of first nests were not different among years ( P > 0.05) or between sites of successful nests and nests destroyed by predators, although the large variances of the variables reduced our power to detect differences. Habitat around sites of renests differed from sites of first nests. Sites around first nests had lower basal area of dead trees ( P = 0.05) and higher stem densities of aspen ( P = 0.03) and cherry saplings ( P = 0.001), and viburnum ( P = 0.05), while renest sites had taller trees ( P = 0.02). The change from nest sites in areas dominated by alders and tree-size gray birch used in 1977-80 to sites dominated by sapling trees, especially aspen, used during 1987-90 suggests that woodcock in the expanding population at the refuge are selecting nest sites created by habitat management since 1979.

Maine↗