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At least 55 records · Page 3Linked to original sources
USGS1988

Agricultural chemicals and the quality of prairie-pothole wetlands for adult and juvenile waterfowl - What are the concerns?

A review of the literature and results of ongoing studies indicates that the potential for agricultural chemicals, particularly aerially-applied insecticides, to enter prairie potholes and reduce the quality of these wetlands for waterfowl is great, and that a coordinated effort by farmers, wildlife managers, and regulatory agencies is needed to minimize these impacts

Biological Report↗
USGS1993

Habitat use and survival rates of wintering American woodcocks in coastal South Carolina and Georgia

Habitat use and survival rates of radio-marked American woodcocks (Scolopax minor) were studied during the winter in coastal South Carolina (1988-89) and Georgia (1989-90). Soon after they arrived, woodcocks were captured in mist nets or in modified shorebird traps or by nightlighting. Each bird was weighed, aged, sexed, and fitted with a 4-g radio transmitter and monitored daily until it died or could not be located or until its radio failed. During the day, the woodcocks in South Carolina frequented seasonally flooded stands of gum-oak-willow (Liquidambar-Quercus-Salix) > 75% of the time and <15-year-old pine (Pinus spp.) plantations during the remaining time. The predominantly used understory vegetation was switch cane (Arundinaria gigantica). In Georgia, woodcocks used bottomland hardwoods, young pine plantations (<15-years-old), mature pine-hardwood stands, and clear-cuttings that had regenerated naturally. Wax myrtle (Myrica cerifera) dominated the used understory species at these sites. The woodcocks in South Carolina rarely made daily moves between daytime and nighttime cover, whereas the birds in Georgia made regular flights. At both sites, the daily survival rates of females were low, especially in the absence of losses from hunting. Daily survival rates of females ranged from 0.992 in adults to 0.994 in young. Daily survival rates of males ranged from 1.0 in adults to 0.996 in young. We determined no significant differences in the daily survival rates of woodcocks by age or sex in either South Carolina or Georgia. Probable predators of radio-marked woodcocks included bobcats (Lynx rufus), gray foxes (Urocyon cinereoargenteus), and barred owls (Strix varia).

Biological Report↗
USGS1990

Estimation of annual indices from roadside surveys

Most of the surveys presently used to estimate population trends on a large geographic scale depend upon repeated visits to a number of randomly selected routes or monitoring points. As these surveys cannot be analyzed by modeling annual mean densities among routes within a region, no natural annual index of population density exists for the region. We discuss two possible methodologies for estimating annual indices of abundance. In the context of the route-regression methodology, in which trends are estimated for each route and regional population trends are estimated as weighted averages of route trends, it is possible to find average residual distances between the predicted trends on each route and the actual data points. Adding these average residuals to the regional predicted values provides a measure of average distance from the actual data points to the predicted trends. A linear model approach can also be used to estimate annual indices, in which a regional slope parameter can be fit to the data in combination with annual effects. Bootstrapping can be used to provide some measure of the variability of these annual effects. These methods provide similar results in an example using Breeding Bird Survey data for scissor-tailed flycatcher (Tyrannlls forficatus) trends in Arkansas and Oklahoma.

Biological Report↗
USGS1993

Critical review of the current knowledge of the biology of the American woodcock and its management on the breeding grounds

We critiqued previous work on the biology and management of the American woodcock (Scolopax minor) on the breeding grounds. We determined that little is known about habitat variables and weather extremes that may limit the population. Most investigators who attempted to define habitat requirements of the woodcock used inadequate sample sizes, limited the duration of their studies, did not account for effects of weather, or failed to adequately measure habitat variables. Furthermore, the effects of hunting on local or regional populations has never been adequately studied. We concluded that obtaining data to understand the biology of the woodcock and the effects of hunting is essential before managers can reverse the long-term decline of woodcock numbers.

Biological Report↗
USGS1993

Techniques for research into woodcocks: experiences and recommendations

We describe methods for the study of the American woodcock (Scolopax minor) at the Moosehorn National Wildlife Refuge. Described are techniques for the capture of particular age-sex cohorts during different times of the year, the aging and sexing, the evaluation of habitat components, and the estimation of population size. We describe successful and tried but rejected techniques with radio-telemetry for the study of survival and habitat use.

Biological Report↗
USGS1993

Behavior of radio-marked breeding American woodcocks

During spring 1986-89, we equipped 175 male and 89 female American woodcocks (Scolopax minor) with radio transmitters. Radio-marking had little effect on behavior; within 1 day of marking, 37 of 64 (58%) displaying males were dominant and within 7 days, 138 of 157 (88%) were dominant. All females marked before nesting proceeded to nest, and marked females with broods remained with broods after release. Dominance of males declined from 73% in April to 69% in May and to 26% in June as breeding activity waned. In all years, after-second-year (ASY) males were dominant more often than second-year (SY) males (67.5% vs. 58.9%). ;Most males displayed at more than one (range = 2-12) site. Distances that males moved between the primary singing ground and subsequent singing grounds averaged 775 m in all years and ranged from 618 m (1986) to 966 m (1988). Females visited males at singing grounds throughout the breeding cycle; some females visited more than one site. During prenesting, females remained in daytime covers during the crepuscular period (55%), flew to different feeding covers (22%), visited singing grounds (14%), or flew from daytime covers to unknown locations (9%). During nesting, females left nests during the crepuscular period (72%) and moved to singing grounds (5%), to feeding areas (59%), and to undetermined locations (7%). Females with broods remained with their broods during the crepuscular period (62%), flew to feeding areas (30%), visited singing grounds (1%), or flew to undetermined locations (6%). The woodcock mating system is similar to a resource-based polygyny. Males compete for singing grounds near high-quality nesting areas. The fitness of males is expressed by dominance at more than one singing ground. Woodcocks are not monogamous; females may visit more than three different males during a single courtship period but do not visit males regularly. Most females leave nests during the crepuscular period to feed in a different cover.

Biological Report↗
USGS1990

Topics in route-regression analysis

The route-regression method has been used in recent years to analyze data from roadside surveys. With this method, a population trend is estimated for each route in a region, then regional trends are estimated as a weighted mean of the individual route trends. This method can accurately incorporate data that is unbalanced by changes in years surveyed and observer differences. We suggest that route-regression methodology is most efficient in the estimation of long-term (>5 year) trends, and tends to provide conservative results for low-density species.

Biological Report↗