Data Owner

Patuxent Wildlife Research Center (PWRC)

Data Access: Level 4

Contact Patuxent Wildlife Research Center, USGS, for permission to use data.

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Abstract

The North American Breeding Bird Survey (BBS), which is coordinated by the Biological Resources Division and Canadian Wildlife Service, is a primary source of population trend and distribution information for most species of North American birds. The BBS was initiated during 1966 by Chan Robbins and his associates at the Patuxent Wildlife Research Center to monitor the populations of all breeding bird species across the continental U.S., Canada, and Alaska. Approximately 2200 skilled observers participate in the survey each year. The BBS has accumulated 30 years of data on the abundance, distribution, and trends for more than 400 species of birds. These data are widely used by researchers, various federal and state agencies, non-governmental organizations, and the general public. Analyses of BBS data by PWRC statisticians have been instrumental in the development of innovative approaches for analyzing trends of wildlife populations.

Purpose

In the 1960's, chlorinated hydrocarbon pesticides and similar poisons were widely used to control insect populations. Pesticide spraying not only killed insects but also killed birds, raising serious concerns over its effects on bird population trends. Unfortunately, no long-term regional or continental population data were available for most bird species, making it difficult for birders to demonstrate declines in bird populations.

The Bird Breeding Survey has proven to be a valuable source of information on bird population trends. Robbins et al. (1986) provided the first continental relative abundance maps for various songbirds based on BBS data. When viewed at continental or regional scales, these maps provide a reasonably good indication of the relative abundance of species that are well sampled by the BBS.

In addition, the BBS is a good source of information on temporal patterns in trends. Populations of permanent resident and short-distance migrant (birds wintering primarily in the U.S. and Canada) species may be adversely affected by episodes of unseasonal weather. The extent of any declines in a particular bird population is known after the data is analyzed.

The BBS is also a good source of geographic patterns in trends. Few species have consistent trends across their entire ranges, so geographic patterns in trends are of considerable interest to anyone concerned with the status of the continent's birds. With the use of a Geographic Information System, route-specific trends are smoothed to produce geographic patterns that are not based on political boundaries or physiographic strata. These analyses allow identification of regions of increase and decline. Once these regions have been pinpointed, researchers can undertake studies that will allow them to identify the factors responsible for the population trends.

Contact

Bruce Peterjohn: bruce_peterjohn@usgs.gov

Keith Pardieck: keith_pardieck@usgs.gov