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J.R. Sauer

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

137 records · Page 8Linked to original sources
USGS1990

North American Breeding Bird Survey Annual Summary, 1989

The North American Breeding Bird Survey (BBS) is run by approximately 2,000 skilled amateur ornithologists and is coordinated cooperatively by the U.S. Fish and Wildlife Service and the Canadian Wildlife Service. Since 1966, BBS cooperators have been collecting standardized information on North American bird populations. The BBS is a roadside survey, comprised of permanent routes that are surveyed yearly. Each route is 39.4 km (24.5 miles) long and consists of 50 stops spaced 0.8 km (0.5 mile) apart. All birds heard or seen during a 3-min observation period at each stop are recorded, and, for each species, the sum of the counts on individual stops is used as an index of species density on the route. Survey routes occur throughout the continental United States and most of Canada. Here, we present the population changes of the 251 bird species reported on the 50 or more BBS routes in the survey region during 1988 and 1989. Population trends for 1966-89 are presented for comparison. The direction and significance of population changes between the years for the 306 species occurring on 10 or more routes within States and Provinces are summarized in Appendix B. The pattern of population changes for selected species is graphically summarized on maps by physiographic stratum.

Biological Report↗
USGS1989

Model-based estimates of annual survival rate are preferable to observed maximum lifespan statistics for use in comparative life-history studies

Estimates of longevity are available for many animals, and are commonly used in comparative life-history analyses. We suggest that annual survival rate is a more appropriate life history parameter for most comparative life history analyses. Observed maximum lifespans estimate complicated functions of survival and sampling probabilities. Annual survival rate estimates derived from modern band-recovery statistical procedures are becoming available for a variety of organisms. We compiled annual survival rate estimates and observed maximum longevities derived from band recovery data for North American waterfowl. Observed maximum longevities were not correlated with the annual survival rate estimates and appear to be unstable over time. We recommend that observed maximum lifespans not be used in life history analyses.

Oikos↗
USGS1989

Buteos

Red-tailed, red-shouldered, and broad-winged hawks nest throughout the 11 northeastern states, and red-tailed, red-shouldered, and rough-legged hawks winter in this region. Historical and present ranges of these species are similar, although red-shouldered and broad-winged hawk ranges now have more vacant patches at a local and regional level. Only the red-shouldered hawk is of special concern or officially listed as threatened by some state agencies. Analysis of Breeding Bird Survey (BBS) data indicated positive trends in counts of red-tailed hawks along the more developed Northeast corridor. No trends were found in analyses of BBS data for red-shouldered hawks in either more- or less-developed regions of the Northeast. Based on the BBS, we found a decreasing trend in counts of broad-winged hawks along the more-developed Northeast corridor, and an increasing trend in less-developed regions of the Northeast. Our analyses of Christmas Bird Count data indicated no trend in counts of red-shouldered nor rough-legged hawks, but an increase in counts of red-tailed hawks from 1962 to 1983. Many individuals believe that species such as the red-shouldered hawk are declining in the Northeast, but no trends were detected in our analyses.

Book chapter↗
USGS1989

Monitoring bird populations with Breeding Bird Survey and atlas data

The principal means of monitoring avian species in North America since 1966 is the Breeding Bird Survey (BBS). Nearly 2000 random roadside rouleS of 50 3-minule stops each are run once each summer by experienced observers. Two-year and 10ng-lerm population trends have been calculated for 250 of the more common species. We show how Breeding Bird Atlas dala for lWO periods of time can also be used to calculale population nends, and we compare atlas neRds with those from the BBS. If coverage is inlensive and consistent belWeen time periods, atlas dala may be useful for monitoring species that are not adequalely sampled by the BBS.

Book chapter↗
USGS1989

Population declines in North American birds that migrate to the neotropics

Using data from the North American Breeding Bird Survey, we determined that most neotropical migrant bird species that breed in forests of the eastern United States and Canada have recently (1978-1987) declined in abundance after a period of stable or increasing populations. Most permanent residents and temperate-zone migrants did not show a general pattern of decrease during this period. Field data from Mexico were used to classify a subset of the neotropical migrants as using forest or scrub habitats during winter. Population declines during 1978-1987 were significantly greater among the forest-wintering species, while populations of scrub-wintering species increased. The same subset of neotropical migrants also showed overall declines in forest-breeding species, but no significant differences existed between species breeding in forest and scrub habitats. Neotropical migrant species that primarily use forested habitats in either wintering or breeding areas are declining, but a statistically significant association between habitat and population declines was detected only in the tropics.

Proceedings of the National Academy of Sciences↗
USGS1989

Program CONTRAST--A general program for the analysis of several survival or recovery rate estimates

This manual describes the use of program CONTRAST, which implements a generalized procedure for the comparison of several rate estimates. This method can be used to test both simple and composite hypotheses about rate estimates, and we discuss its application to multiple comparisons of survival rate estimates. Several examples of the use of program CONTRAST are presented. Program CONTRAST will run on IBM-cimpatible computers, and requires estimates of the rates to be tested, along with associated variance and covariance estimates.

Fish and Wildlife Technical Report↗
USGS1989

North American Breeding Bird Survey Annual Summary, 1988

Introduction: The North American Breeding Bird Survey (BBS) is run by approximately 2,000 skilled amateur ornithologists, and is coordinated cooperatively by the U.S. Fish and Wildlife Service and the Canadian Wildlife Service. Beginning in 1966, BBS cooperators have been collecting standardized information on North American bird populations. The BBS is a roadside survey, comprised of permanent routes that are surveyed yearly. Each route is 39.4 km (24.5 miles) long and consists of 50 stops spaced 0.8 km (0.5 mile) apart. All birds heard or seen during a 3-min observation period at each stop are recorded, and the sum of the individual stops for each species is used as an index of species density on the route. In this report, we present the population changes of the 222 bird species reported on > 50 BBS routes during 1987 and 1988. Population trends for 1966-87 are presented for comparison. Owing to space constraints, trends are not reported for States, Provinces, or physiographic regions. Instead, we present maps illustrating patterns of population change for selected species, and summarize State and physiographic strata patterns of population change as the proportion of species that increased in each region. Detailed State, Provincial, and physiographic strata changes arc available to interested readers.

Biological Report↗