| Abstract: | Low annual survival of hatching-year (HY) females is a critical management concern for canvasbacks (Aythya valisineria), and may contribute substantially to reduced reproductive potential and the male-biased sex ratio of the species. To evaluate the contribution of mortality on a traditional wintering area to low annual survival, we estimated survival rates of HY female canvasbacks during 3 winters (1987-89) on Chesapeake Bay. We implanted radio transmitters in 204 HY and 44 after-hatching-year (AHY; 1989 only) female canvasbacks and tracked them from mid-December to early March. Ten-week survival rates did not differ (P > 0.05) among years for HY females; estimates ranged from 0.833 to 0.930 and averaged 0.887. Of 17 mortalities recorded for HY females during the 3-year study, 14 of 15 dated deaths occurred during the duck hunting season (first 3 weeks of the study), even though the hunting season on canvasbacks was closed. As a result, survival rates were lower during hunting versus posthunting periods (P 5 0.05 for 2 of 3 yr). Illegal hunting was the single largest source of mortality for HY females. Shot ducks accounted for a loss of 4% and suspected crippling losses (ducks scavenged by shoreline predators) may have increased hunting-associated losses to as high as 7%. In 1989, no deaths were observed for AHY females, and their survival was higher (P = 0.02) than HY females. High winter survival for HY females indicates that substantial mortality occurs at some other time of the annual cycle. |
| Genre: | Article |
| ProdID: | 5222828 |
| Citation Author: | Haramis, G. M.; Jorde, D. G.; Bunck, C. M. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation End Page: | 771 |
| Citation Issue: | 4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Wildlife Management |
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| Citation Number Of Pages: | 9 |
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| Citation Phsyical Description: | 763-771 |
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| Citation Search Results Text: | Survival of hatching-year female canvasbacks wintering on Chesapeake Bay; 1993; Article; Journal; Journal of Wildlife Management; Haramis, G. M.; Jorde, D. G.; Bunck, C. M. |
| Citation Start Page: | 763 |
| Citation Volume: | 57 |
| Citation Year: | 1993 |
| Type: | citation/reference |
| Text: | Survival of hatching-year female canvasbacks wintering on Chesapeake Bay; 1993; Article; Journal; Journal of Wildlife Management; Haramis, G. M.; Jorde, D. G.; Bunck, C. M. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DOCUMENT): | http://www.jstor.org/stable/3809077 |
| Date Other: | Wed, 16 Jun 2010 12:18 -0500 |
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