| 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. |
| Genre: | Article |
| ProdID: | 5222886 |
| Citation Author: | Peterjohn, B.G.; Sauer, J.R. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation End Page: | 67 |
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| Citation Language: | English |
| Citation Larger Work Title: | Bird Populations |
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| Citation Number Of Pages: | 16 |
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| Citation Phsyical Description: | 52-67 |
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| Citation Search Results Text: | North American Breeding Bird Survey annual summary 1990-1991; 1993; Article; Journal; Bird Populations; Peterjohn, B.G.; Sauer, J.R. |
| Citation Start Page: | 52 |
| Citation Volume: | 1 |
| Citation Year: | 1993 |
| Type: | citation/reference |
| Text: | North American Breeding Bird Survey annual summary 1990-1991; 1993; Article; Journal; Bird Populations; Peterjohn, B.G.; Sauer, J.R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 16 Jun 2010 12:18 -0500 |
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