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Estimating Population Growth and Recruitment Rates Across the Range of American Common Eiders |
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| Authors: | Jean-François Giroux Martin Patenaude-Monette Scott G Gilliland G Randy Milton Glen J Parsons Mark L Gloutney Katherine R Mehl R Bradford Allen Daniel G McAuley Eric T Reed Nic R McLellan |
| Institution: | 1. Département des sciences biologiques, Université du Québec à Montréal, 141 Président Kennedy, P.O. Box 8888, Station Centre-ville, Montreal, QC, H3C 3P8 Canada;2. Canadian Wildlife Service, Environment and Climate Change Canada, 17 Waterfowl Lane, P.O. Box 6227, Sackville, NB, E4L 1G6 Canada;3. Department of Lands and Forests, 136 Exhibition Street, Kentville, NS, B4N 4E5 Canada
Current affiliation: Institute for Land, Water, and Society, Charles Sturt University, Albury, NSW 2640, Australia;4. Department of Biology, Acadia University, Wolfville, NS, B4P2R6, Canada;5. Department of Lands and Forests, 136 Exhibition Street, Kentville, NS, B4N 4E5 Canada;6. Ducks Unlimited Canada, 350 Sparks Street Suite 706, Ottawa, ON, K1R 7S8 Canada;7. Ducks Unlimited Canada, 562 Water Street, St. John's, NL, A13 2A2 Canada Present affiliation: Fish, Wildlife, and Lands Branch, Saskatchewan Ministry of Environment, 112 Research Drive, Saskatoon, SK, S7K 2H6, Canada;8. Maine Department of Inland Fisheries and Wildlife, 650 State Street, Bangor, ME, 04401 USA;9. USGS Patuxent Wildlife Research Center, 69 Grove Street Extension, Orono, ME, 04473 USA;10. Canadian Wildlife Service, Environment and Climate Change Canada, 5019- 52nd Street, Yellowknife, NWT, X1A 2P7 Canada;11. Ducks Unlimited Canada, 64 Hwy 6, P. O. Box 430, Amherst, NS, B4H 3Z5 Canada |
| Abstract: | Sound management of bird populations rests upon an adequate understanding of their population dynamics. Our study evaluated recruitment and population growth rates of 14 American common eider (Somateria mollissima dresseri) colonies from Labrador, Nova Scotia, Quebec, Canada, and Maine, USA, during various periods between 1970 and 2019. We used Pradel mark-recapture models to estimate colony-specific growth rates and the relative contributions of survival and recruitment on growth. We also validated this approach using annual nest counts (~8,000 pairs) conducted between 2003 and 2019 during down harvest operations in 3 colonies located in the Saint Lawrence estuary in Quebec. There was generally a good agreement between estimates derived using the 2 approaches. We considered that capture-recapture data were suitable to estimate population trends of common eiders in other colonies, especially for colonies where accurate nest monitoring is impaired by dense vegetation. The breeding abundance declined at major colonies in Maine and Nova Scotia and increased or was stable in Quebec and Labrador. Female survival contributed the most to population growth, but variation in recruitment among colonies was more important than variation in survival to explain population growth. Management measures should thus strive to maximize local recruitment in colonies with declining populations. The assumption that apparent survival probabilities were homogeneous throughout an individual capture history was violated at several colonies in Quebec and Labrador. Using recaptures and band recoveries, we showed that the lower apparent survival for newly marked individuals compared to females that had been recaptured at least once was caused by a difference in site fidelity rather than true survival. But <1% of recaptured females dispersed to another colony for breeding, indicating that the lower site fidelity could be related to heterogeneity in capture probability among individuals. © 2021 The Wildlife Society. |
| Keywords: | Atlantic Flyway capture marking recapture common eider MARK Pradel models recruitment survival Somateria mollissima dresseri |