| Abstract: | Data from the North American Breeding Bird Survey were used to estimate continental and regional changes in bird populations for the 2-year periods of 1993-1994 and 1994-1995. These 2-year changes were placed in the context of population trends estimated over the 1966-1995 interval. The 2-year changes were more positive during the 1993-1994 period, when 54.2% of all species exhibited positive continental trend estimates. This percentage was reduced to 47.7% during 1994-1995, as compared with 50.5% of all species having positive continental trend estimates over then entire survey period. In general, the percentage of increasing species in the Central and Western BBS regions was highest during 1993-1994, with a very marked decline in the Western BBS Region during 1994-1995. The percentage was highest in the Eastern BBS Region during 1994-1995. The continental and regional percentages of species with positive trend estimates were also analyzed for 12 groups of North American birds having shared life-history traits. Over the entire survey period, grassland birds remain the species group with the smallest percentage of increasing species. Trends during these 2-year intervals do not indicate any consistent improvement in the overall declines experienced by grassland birds since the mid-1960s. |
| Genre: | Article |
| ProdID: | 5223201 |
| Citation Author: | Peterjohn, B.G.; Sauer, J.R.; Link, W.A. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation End Page: | 66 |
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| Citation Language: | English |
| Citation Larger Work Title: | Bird Populations |
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| Citation Number Of Pages: | 19 |
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| Citation Phsyical Description: | 48-66 |
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| Citation Public Comments: | The date on this issue of Bird Populations is 1995-1996 |
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| Citation Search Results Text: | The 1994 and 1995 summary of the North American Breeding Bird Survey; 1996; Article; Journal; Bird Populations; Peterjohn, B.G.; Sauer, J.R.; Link, W.A. |
| Citation Start Page: | 48 |
| Citation Volume: | 3 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | The 1994 and 1995 summary of the North American Breeding Bird Survey; 1996; Article; Journal; Bird Populations; Peterjohn, B.G.; Sauer, J.R.; Link, W.A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 16 Jun 2010 12:18 -0500 |
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