| Abstract: | Band-recovery data, harvest surveys, and spring and winter population surveys were used to estimate population parameters of ring-necked ducks (Aythya collaris). Mean annual survival rates of adult males (0.63 to 0.69) were higher (P < 0.05) than those of either adult females (0.48 to 0.58) or juveniles (0.31 to 0.41). Survival rates of winter-banded adult males were highest in the Mississippi Flyway (0.69), whereas those of females were highest in the Atlantic Flyway (0.58). Recovery rates varied little geographically, were similar for adult males and females, and were higher (P < 0.01) for juveniles. Survival rates of winter-banded adult males in the Mississippi Flyway were negatively correlated with annual harvest rate indices (r = -0.78, P < 0.01) and breeding population indices r = -0.68, P< 0.05). These results are contradictory, because the 1st correlation suggests an additive relationship between hunting and non-hunting mortality, whereas the 2nd suggests compensatory (density-dependent) mortality. Fall age-ratios of ring-necked ducks for 1961-80 were not significantly different between the Mississippi (1.29 young/adult) and the Atlantic (1.18 young/adult) Flyways. Estimated survival rates were used in conjunction with these age-ratios to project finite rates of increase at stable age distributions of approximately 1.0 for the Mississippi and the Atlantic Flyways. Mixing between the 2 Flyway populations and temporal variability in survival rates and age-ratios suggest a population with long-term stationarity but subject to large short-term fluctuations in growth rate. Breeding population surveys for 1960-80 corroborate these results, with breeding populations ranging from 200,000 to 800,000 ( = 500,000) but exhibiting no overall trends |
| Genre: | Article |
| ProdID: | 5224198 |
| Citation Author: | Conroy, M.J. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation Language: | English |
| Citation Larger Work Title: | Transactions of the Northeast Section of the Wildlife Society |
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| Citation Phsyical Description: | 108 (abstract) |
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| Citation Search Results Text: | Population dynamics of ring-necked ducks in the Atlantic and Mississippi flyways; 1982; Article; Journal; Transactions of the Northeast Section of the Wildlife Society; Conroy, M.J. |
| Citation Start Page: | 108 (abs) |
| Citation Volume: | 39 |
| Citation Year: | 1982 |
| Type: | citation/reference |
| Text: | Population dynamics of ring-necked ducks in the Atlantic and Mississippi flyways; 1982; Article; Journal; Transactions of the Northeast Section of the Wildlife Society; Conroy, M.J. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 16 Jun 2010 12:19 -0500 |
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