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For the past 25 years estimation of mortality rates for waterfowl has been based almost entirely on the composite dynamic life table. We examined the specific assumptions for this method and derived a valid goodness of fit test. We performed this test on 45 data sets representing a cross section of banded sampled for various waterfowl species, geographic areas, banding periods, and age/sex classes. We found that: (1) the composite dynamic method was rejected (P <0.001) in 37 of the 45 data sets (in fact, 29 were rejected at P <0.00001) and (2) recovery and harvest rates are year-specific (a critical violation of the necessary assumptions). We conclude that the restrictive assumptions required for the composite dynamic...
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Abstract has not been submitted
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Ungulates are key components in ecosystems and economically important for sport and subsistence harvest. Yet the relative importance of the effects of weather conditions, forage productivity, and carnivores on ungulates are not well understood. We examined changes in elk (Cervus canadensis) recruitment (indexed as age ratios) across 7 states and 3 ecotypes in the northwestern United States during 1989–2010, while considering the effects of predator richness, forage productivity, and precipitation. We found a broad‐scale, long‐term decrease in elk recruitment of 0.48 juveniles/100 adult females/year. Weather conditions (indexed as summer and winter precipitation) showed small, but measurable, influences on recruitment....
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We estimated nest success of mallard (Anas platyrhynchos), gadwall (A. strepera), blue-winged teal (A. discors), northern shoveler (A. clypeata), and northern pintail (A. acuta) for 5 regions in North Dakota, South Dakota, and Minnesota, for 1-3 periods between 1966 and 1984, and for 8 habitat classes. We obtained composite estimates of nest success for regions and periods by weighting each habitat proportional to the number of nest initiations. The distribution of nest initiations was derived from estimates of breeding populations, preferences of species for nesting habitats, and availability of habitats. Nest success rates ranged from < 5 to 36% among regions, periods, and species. Rates were lowest in western...
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The mourning dove (Zenaidura macroura) call-count survey is a nationwide audio-census of breeding mourning doves. Recent analyses of the call-count routes have utilized a stratification based upon physiographic regions of the United States. An analysis of 5 years of call-count data, based upon stratification using potential natural vegetation, has demonstrated that this uew stratification results in strata with greater homogeneity than the physiographic strata, provides lower error variance, and hence generates greatet precision in the analysis without an increase in call-count routes. Error variance was reduced approximately 30 percent for the contiguous United States. This indicates that future analysis based...
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I analyzed data from the 1984 and 1986 Federal Waterfowl Hunter Questionnaire Survey (WHQS) to estimate the rate of return of name and address contact cards, to evaluate the efficiency of the Survey's stratification scheme, and to investigate potential sources of bias due to nonresponse at the contact card and questionnaire stages of the Survey. Median response at the contact card stage was 0.200 in 1984 and 0.208 in 1986, but was lower than 0.100 for many sample post offices. Large portions of the intended sample contributed little to the final estimates in the Survey. Differences in response characteristics between post office size strata were detected, but size strata were confounded with contact card return...
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Adult females in a cottontail (Sylvilagus floridanus) population produced seven or eight litters during the 1961 breeding season. A synchrony of the conception dates was maintained throughout the breeding season. Data about ovulation rate, prenatal mortality, and litter size for each litter are presented. The first litter was smallest, averaging about three young, and the remaining litters ranged between five and six young. The last four litters may be slightly smaller than the second and third litters of the season. The total annual production of young by an adult female would be approximately 35.
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Observations were made concerning the diseases and parasites of a group of woodcocks (Philohela minor) caught in Massachusetts in the summer of 1960 and kept in captivity in Maryland, and of another group caught and kept in Louisiana in the winter of 1960-61. Bumblefoot, a granulomatous swelling of the foot caused by Micrococcus sp., is reported for woodcocks for the first time. Six of 31 woodcocks were infected with a renal coccidium of an undetermined species. Tetrameres sp. was found in 4 of 31 birds examined. Sarcocystis was found in one bird. Aerosaculitis was found in several.
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Age and sex ratio statistics are often a key component of the evaluation and management of wildlife populations. These statistics are determined from counts of animals that are commonly plagued by errors associated with either survey design or visibility bias. We present age and sex ratio estimators that incorporate both these sources of error and include the typical situation that animals are sampled in groups. Aerial surveys of elk (Cervus elaphus) in northcentral Idaho illustrate that differential visibility of age or sex classes can produce biased ratio estimates. Visibility models may be used to provide corrected estimates of ratios and their variability that incorporates errors due to sampling, visibility...
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Methiocarb [4-(methylthio)-3,-5-xylyl N-methylcarbamate] was tested as a seed treatment for repelling blackbirds and crows (Corvus sp.) from sprouting corn in South Carolina. The test was conducted on eight fields within a 0.25-square-mile area. Marked repellency occurred; sprout damage averaged 44 percent in the control fields and 0.3 percent in the fields treated with methiocarb.
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Duckling survival in wood duck (Aix sponsa) and mallard (Anas platyrhynchos) broods was estimated from data obtained from 71 radio-marked brood hens on a study area in north-central Minnesota. Radio-marked hens produced 30 broods during the study, and 41 hens already leading broods were captured and radio-marked. Production estimates based on brood size counts were inflated by about 38 percent for wood ducks and 30 percent for mallards if total-brood losses were not taken into account. Mortality during the first 2 weeks of life was most severe, accounting for 86 percent of total recorded mortality in wood ducks and 70 percent in mallards. Rearing success was about 41 percent for wood ducks and 44 percent for mallards....
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Ospreys (Pandion haliaetus) have been the focus of conservation efforts since their dramatic population decline attributed to dichlorodiphenyltrichloroethane and related chemicals in the 1960s. Several recent studies of ospreys nesting in the United States have indicated improved reproduction. However, the density of breeding ospreys varies greatly among locations, with some areas seemingly habitable but not occupied. Because of concerns about pollution in the highly industrialized portions of the Delaware River and Bay, USA, we evaluated contaminant exposure and productivity in ospreys nesting on the Delaware River and Bay in 2002. We characterized habitat in the coastal zone of Delaware, USA, and the area around...
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Introduced brushtail possums (Trichosurus vulpecula) are a widespread pest of conservation and agriculture in New Zealand, and considerable effort has been expended controlling populations to low densities. A national protocol for monitoring the abundance of possums, termed trap catch index (TCI), was adopted in 1996. The TCI requires that lines of leghold traps set at 20-m spacing are randomly located in a management area. The traps are set for 3 fine nights and checked daily, and possums are killed and traps reset. The TCI is the mean percentage of trap nights that possums were caught, corrected for sprung traps and nontarget captures, with trap line as the sampling unit. We studied I forest and I farmland area...
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We seeded experimental plots with number 4 lead pellets and sampled these plots for 10 years to assess the settlement rate of pellets in tundra wetland types commonly used by foraging waterfowl. After 10 years, about 10% of pellets remained within 6 cm of the surface, but >50% remained within 10 cm. We predict that spent lead pellets will eventually become unavailable to waterfowl; however, it will likely require >25 years for all pellets to exceed depths at which waterfowl species may forage.
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The distribution of polar bears (Ursus maritimus) is circumpolar in the NOrthern Hemisphere, but known locations of maternal dens are concentrated in relatively few, widely scattered locations. Denning is either uncommon or unknown within gaps. To understand effects of industrial development and propose increases in hunting, the temporal and spatial distribution of denning in the Beaufort Sea must be known. We caputred and radiocollared polar bears between 1981 and 1991 and determined tht denning in the Beaufort Sea region was sufficient to account for the estimated population there. Of 90 dend, 48 were on drifting pack ice, 38 on land, and 4 on land-fast ice. The portions of dens on land was higher (P= 0.029) in...