Geographic patterns in relative abundances and population trends of breeding and wintering loggerhead shrikes in North America
In North America, the Breeding Bird Survey and the Christmas Bird Count provide data that are collected at sites visited each year, and the site-specific data can be placed in a Geographic Information System and smoothed to produce contour maps of relative abundance and trend for the United States and southern Canada. We develop these contour maps for Loggerhead Shrike (Lanius ludovicianus) data from both surveys, and compare the patterns derived from each survey to evaluate the consistency of trends and relative abundances within physiographic strata. Patterns in relative abundance seem to be associated with strata, especially in the breeding season, but trends are often heterogeneous within strata. Because of limitations of the surveys and observed geographic patterns of shrike trends in the survey data, we suggest that there is no natural scale for the analysis of shrike-habitat associations.
Citation Information
Publication Year | 1995 |
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Title | Geographic patterns in relative abundances and population trends of breeding and wintering loggerhead shrikes in North America |
Authors | J.R. Sauer, Sandra Orsillo, B.G. Peterjohn |
Publication Type | Book Chapter |
Publication Subtype | Book Chapter |
Index ID | 5210723 |
Record Source | USGS Publications Warehouse |
USGS Organization | Patuxent Wildlife Research Center |