Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Trends”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,387 records · Page 77Linked to original sources
USGS1974

Monitoring bird population trends

The Breeding Bird Survey monitors annually the breeding populations of nearly 500 bird species by means of 2,000 random roadside counts of fifty 3-minute stops each. Results are computer-analyzed by State and Province, physiographic and geographic regions, and for the entire continent. Short- and long-term population changes are detected and maps showing distribution and relative abundance are prepared. A computerized bibliography of breeding bird censuses currently in preparation will permit retrieval of bird density data by bird species, plant community, and geographic location. These two programs will greatly facilitate management for nongame species.

Book chapter↗
USGS1983

Monitoring bird population trends in North America

Se ofrece un nuevo metodo para computar las oscilaciones demograficas de las aves a lo largo de los anos. Con los datos suministrados por el proyecto 'Aves nidificantes en Norteamerica' , se indican en la Tabla 1 las pautas de cambio numerico de una serie seleccionada de aves holarticas.

Book chapter↗
USGS1995

Population trends of the loggerhead shrike from the North American Breeding Bird Survey

North American Breeding Bird Survey data indicated a general decline in Loggerhead Shrike (Lanius ludovicianus) populations during 1966-1993. At the continental level, shrikes declined at an average rate of 2.9% per year. Average rates of regional declines varied from 2.5-3.4% annually. These declines were prevalent in most states, provinces, and physiographic strata. Only the Edwards Plateau, High Plains, and Great Plains Roughlands strata, and Colorado, Louisiana, Montana, and South Dakota apparently have stable breeding populations. Severe winter weather during 1976-1979 may have contributed to this decline in the eastern half of the continent, combining with other factors during the winter and breeding seasons that have been implicated in the rangewide decline of this species.

Book chapter↗