| Abstract: | Population trends for North American species are calculated for 1966-‘91 and 1982-‘91 using Nonh American Breeding Bird Survey data. Species are grouped into 3 systems of guild classifications representing migration status, breeding habitat and nesting substrate. Trends for these groups are summarized by time period, bioregion and physiographic region. At the continental level, declines approximately equalled increases. There are slightly more declines during the last 10 years. Prairie populations declined more than expected, while western populations increased. Scrub and grassland nesting species declined significantly in several bioregions while woodland species increased. Most guilds did not depart significantly from a ratio of 50:50 increases to decreases or have opposing trends in different bioregions. Guild group changes are usually clustered geographically. Guild and other analyses that search for patterns among population trend estimates offer an excellent means of identifying critical conservation issues. |
| Genre: | Book chapter |
| ProdID: | 5210708 |
| Citation Author: | Droege, S.; Sauer, J.R. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation Editor: | Hagemeijer, E.J.M.; Verstrael, T.J. (editors) |
| Citation End Page: | 306 |
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| Citation Language: | English |
| Citation Larger Work Title: | Bird Numbers 1992: Distribution, monitoring and ecological aspects |
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| Citation Phsyical Description: | viii, 728 |
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| Citation Public Comments: | Proceedings of the 12th International Conference of the International Bird Census Committee (IBCC) and the European Ornithological Atlas Committee (EOAC) held September 14-18, 1992, Noordwijkerhout, Netherlands. SOVON stands for Samenwerkende Organisaties Vogelondersoek Nederland. oclc: 34201893 PDF on file: 4542_Droege.pdf |
| Citation Publisher: | Statistics Netherlands and SOVON |
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| Citation Search Results Text: | Are more North American species decreasing than increasing?; 1994; Book chapter; Bird Numbers 1992: Distribution, monitoring and ecological aspects; Droege, S.; Sauer, J.R. |
| Citation Start Page: | 297 |
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| Citation Year: | 1994 |
| Type: | citation/reference |
| Text: | Are more North American species decreasing than increasing?; 1994; Book chapter; Bird Numbers 1992: Distribution, monitoring and ecological aspects; Droege, S.; Sauer, J.R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Tue, 9 Jun 2009 09:23 -0500 |
| Publisher: | Statistics Netherlands and SOVON |
