Abstracts of Published Breeding Bird Survey Summaries: 1990-1991
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NORTH AMERICAN BREEDING BIRD SURVEY ANNUAL SUMMARY 1990-1991
�
�Bruce G. Peterjohn
�U.S. Fish and Wildlife Service
�Office of Migratory Bird Management
�Laurel, Maryland 20708
�and
 John R. Sauer
�U.S. Fish and Wildlife Service
�Patuxent Wildlife Research Center
�Laurel, Maryland 20708

� Abstract.� 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, 1:1-15 (1993)

 

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