Search USGS⌕ Search

Geology topics

J.R. Sauer

Publications and source records attributed to J.R. Sauer.

At least 127 records · Page 7Linked to original sources
USGS1993

Monitoring goals and programs of the United States Fish and Wildlife Service

The United States Fish and Wildlife Service coordinates several surveys that collect information on the population status of migratory birds in North America. The North American Breeding Bird Survey is the primary source of population information on nongame birds during the breeding season, and waterfowl surveys are conducted during breeding and wintering seasons. The surveys are international in scope, based upon research into sampling methods for birds, and used in management of migratory birds. The Service also maintains the Bird Banding Laboratory in cooperation with the Canadan Wildlife Service, and supports demographic monitoring of bird populations.

Book chapter↗
USGS1993

Population trends and management opportunities for neotropical migrants

The Breeding Bird Survey shows that certain Neotropical migrant songbird populations have been declining over the past 26 years. Among them are forest birds that require extensive forest on the breeding grounds and also forested habitats on tropical wintering grounds. Other species have shown significant declines only since the early 1980's. Birds with broader habitat tolerance, such as those that winter commonly in agricultural and early-successional habitats as well as primary forest, show fewer consistent declines. Several grassland species have also been declining for more than two decades. Populations of many other Neotropical migrants have been stable or increasing over these periods. Examples of 26-year population trends are given. A dozen recommendations are given for managing nesting habitat for Neotropical migrants.

Book chapter↗
USGS1993

North American Breeding Bird Survey annual summary 1990-1991

The North American Breeding Bird Survey (BBS) was used to estimate continental and regional changes in bird populations during 1989-1990 and 1990-1991, placing these short-term changes within the context of population trends since 1966. For the entire survey area, 51.7% of the species exhibited increases in population size during 1989-1990, reversing the decreasing tendency exhibited by the majority of species during 1988-1989. A similar percentage (51.4%) of species with increasing populations was noted during 1990-1991. These percentages were also analyzed for 12 guilds of North American birds and 3 broad geographical regions. Many regional patterns exist in these population changes, reflecting the variability inherent in short-term population fluctuations. Two-year (1989-1990 and 1990-1991) changes and long-term (1966-1990) continental trends are provided for 255 species.

Bird Populations↗
USGS1992

Black duck population units as determined by patterns of band recovery

To estimate regional survival and band recovery rates for waterfowl populations, banding sites must be grouped for data analysis. We group American black duck banding sites using cluster analysis of pairwise comparisons of the distributions of band recoveries. We propose 6 population units, substantially fewer than the 27 black duck reference areas currently used. Flyways do not seem to reflect the population affInities of black ducks.

Book chapter↗
USGS1992

A stochastic population model of mid-continental mallards

We developed a simulation model that integrates infonnation on factors affecting the population dynamics of mallards in the mid-continental region of the United States. In the model we vary age, body mass, and reproductive and molt status of simulated females. Females use several types of nesting and foraging habitat in 15 geographic areas. Deterministic and stochastic events cause mortality or attribute changes on a daily basis, depending on current attributes, habitat, area, calendar date, wetland conditions, temperature, and various mortality agents. Because the model encompasses the entire year, it can be used to examine cross-seasonal effects. A simulated increase in nest success from 0.14 to 0.17 changed the annual rate of population growth from -6% to -1 %. A simulated 75% reduction in lead poisoning changed the rate from -6% to -3%.

Book chapter↗
USGS1992

Geographic patterns in population trends of neotropical migrants in North America

We use the route-regression method to estimate the population trends of 100 species of Neotropical migrants using data from the North American Breeding Bird Survey (BBS). We examine long-term (1966-1988) and recent (1978-1988) trends. In the long-term, more species of Neotropical migrants were increasing than were decreasing in the eastern and western parts of the continent, but recent trends indicate that more species decreased than increased in their population index in the east. Recent population declines in the eastern part of the continent were primarily associated with bird species that breed in forested habitat. No association was detected between changes in forest acreages by state and population trends of Neotropical migrants in the United States and Canada.

Book chapter↗
USGS1992

Winter habitat occurrence patterns of temperate migrant birds in Belize

We used mist nets and point counts to sample bird populations in 61 sites in Belize during January-March of 1987-1991. Sites were classified as forest, second growth, woody agricultural crops (citrus, mango, cacao, and cashew), or non-woody agricultural crops (rice and sugar cane). We evaluated patterns of occurrence of wintering temperate migrant bird species in these habitats. Mist net captures of 22 of 31 migrant species differed significantly among habitats. Of these, 13 species were captured more frequently in the agricultural habitats. American Redstart (Setophaga ruticilla), Black-and-white Warbler (Mniotilta varia), and Magnolia Warbler (Dendroica magnolia) were among the species captured most frequently in woody agricultural habitats; captures of Common Yellowthroat (Geothlypis trichas), Indigo Bunting (Passerina cyanea), and Northern (lcterus galbula) and Orchard orioles (I. spur/anus) were highest in the non-woody agricultural sites. We relate these occurrence patterns to trends in breeding populations in North America. While count data provide a wide picture of winter habitat distribution of migrants, more intensive work is necessary to assess temporal and geographic variation of migrant bird use of agricultural habitats.

El Pitirre (Society of Caribbean Ornithology)↗
USGS1991

Breeding Bird Survey and bird banding data: Applications to raptor research and management

The Breeding Bird Survey (BBS) and Bird Banding Laboratory (BBL) are sources of information for raptor biologists. The BBS has been conducted each year since 1966 in the United States and Canada; historical bird banding records extend back to the early 20th century. BBS data can be used to document population trends and breeding distributions of many bird species. Banding data are generally collected for specific and local studies of bird populations or behavior. Past use of these data has been limited by their volume and relative inaccessibility. In this paper, we present an overview of BBS and BBL raptor data and their uses, limitations and availability.

Book chapter↗
USGS1990

Wood duck population trends from the North American Breeding Bird Survey

The North American Breeding Bird Survey (BBS) has been conducted yearly since 1966, and can be used to describe relative population density and trends of birds in North America north of Mexico. Wood ducks (Air sponsa) are difficult to survey using conventional waterfowl monitoring techniques, but a large portion of their range is surveyed by the BBS. Wood ducks are detected at low densities on many BBS routes, and population trends can be estimated for most regions. Populations have been increasing throughout North America since 1966, but statistically significant increases generally occurred only in the early (1966-78) part of the period. Roadside survey methodology used in the BBS has limitations that make it inefficient as a survey technique for wood ducks, and we recommend using modified methodologies that specifically survey wood duck habitat.

Book chapter↗
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↗
USGS1990

Northern bobwhite, gray partridge, and ring-necked pheasant population trends (1966-1988) from the North American Breeding Bird Survey

We use North American Breeding Bird Survey data to estimate population trends for 1966-1988 for northern bobwhite (Colinus virginianus), ring-necked pheasant (Phasianus colchicus), and gray partridge (Perdix perdix). Bobwhite populations have undergone widespread declines, pheasant have undergone major declines in eastern North America with mixed trends elsewhere, gray partridge have undergone primarily population increases. We present suggestions for further uses of these data.

Book chapter↗
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↗
USGS1990

Recent population trends of the eastern bluebird

North American Breeding Bird Survey data for the period 1966-1987 indicate that Eastern Bluebird (Sialia sialis) populations declined during the 1970s, primarily in association with either severe winters or severe spring storms. In recent years, bluebird populations have increased to levels similar to those observed during the first year (1966) of the survey. Survey results suggest that climate has an important role in affecting short-term population declines in bluebirds.

The Wilson Bulletin↗