| Abstract: | Landscape-scale examination of parasitism patterns of Brown-headed Cowbirds (Molothrus ater) revealed heterogeneous parasitism rates across the mosaic of a forest and associated oldfield communities. In a two-year study in Dutchess County, New York, we found a significantly higher parasitism rate in the forest-interior community (n = 301 nests; 17 species) than on the species in the adjacent and nearby old-field and edge (n = 328 nests; 15 species; 32.3% versus 6.5%; p lt 0.0001). Cowbirds invaded a mature 1300-ha forest stand even when their traditional host species were available in adjacent old-field and edge habitats. The forest and old field study areas were located in a 38,000-ha township with 55% forest cover and contained numerous agriculture, dairy, and horse farms that provided favorable habitat for cowbirds, within-forest examination of parasitism patterns revealed four aspects of cowbird parasitism that contrasted with patterns described in other regions; (1) parasitism was concentrated significantly more often on ground and low-nesting (nests ltoreq 1 m) forest species than on medium- and high nesting species (nests gt 1 m; 35. 01 % versus 2993%; p = 0.0393); (2) parasitism was not significantly greater on Neotropical migrant species than on short-distance migrants and residents; (3) the parasitism rate was not higher in nests close to edges; and (4) the parasitism level was low on certain forest species (such as Wood Thrush) that have experienced high parasitism levels in the Midwest. From a management perspective these data suggest that cowbirds exhibit regional differences in host and habitat use; the target host community of a particular cowbird population is unpredictable at the landscape scale; and a landscape scale should be used in designing cowbird studies to accurately assess local population dynamics. |
| Genre: | Article |
| ProdID: | 5222626 |
| Citation Author: | Hahn, D.C.; Hatfield, J.S. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation End Page: | 1424 |
| Citation Issue: | 6 |
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| Citation Language: | English |
| Citation Larger Work Title: | Conservation Biology |
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| Citation Number Of Pages: | 10 |
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| Citation Phsyical Description: | 1415-1424 |
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| Citation Public Comments: | 4752_Hahn.pdf |
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| Citation Search Results Text: | Parasitism at the landscape scale: Cowbirds prefer forests; 1995; Article; Journal; Conservation Biology; Hahn, D.C.; Hatfield, J.S. |
| Citation Start Page: | 1415 |
| Citation Volume: | 9 |
| Citation Year: | 1995 |
| Type: | citation/reference |
| Text: | Parasitism at the landscape scale: Cowbirds prefer forests; 1995; Article; Journal; Conservation Biology; Hahn, D.C.; Hatfield, J.S. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DOCUMENT): | http://www.jstor.org/stable/2387187 |
| Date Other: | Wed, 16 Jun 2010 12:17 -0500 |
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