Second North American Sea Duck Conference - Patuxent Wildlife ...

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SECOND NORTH AMERICAN SEA DUCK CONFERENCE FACTORS AFFECTING, AND CONSEQUENCES OF, MALE ATTENDANCE AT A COMMON EIDER COLONY IN THE CANADIAN ARCTIC Kerrith McKay¹, H. Grant Gilchrist², and Tom D. Nudds³ ¹University of Guelph and Canadian Wildlife Service; kmckay@uoguelph.ca ²Canadian Wildlife Service, National Wildlife Research Centre, Carelton University ³Zoology Department, University of Guelph Typically, male sea ducks follow females to breeding grounds where they guard their mates against extra pair copulations (EPC), although they rarely follow females directly to nests. However, among common eiders (Somateria mollissima), there is considerable variation in male attendance of females at nests; both between and within colonies. Why does this variation exist, and what do male common eiders gain by attending colonies? Previously, we found that males rarely attend females onto colonies under conditions where there are resident mammalian predators and/or vegetation that confers an advantage to a predator (McKay et al. submitted a). On colonies where males do attend females, we predicted that nest attendance by males may increase their annual reproductive success by, 1) contributing directly to nest site selection and hatching success, 2) protecting their paternity by defending their female against extra-pair copulations, and/or 3) by attempting EPCs themselves while in close proximity to other females on the colony. At a large eider colony near Southampton Island in the Canadian Arctic, we found that males did not participate in nest site selection or nest defense, nor did the duration of their attendance affect the number of eggs that hatched successfully (McKay et al. submitted b). We also collected observational data from over 1000 nests, between 2000-2003, to determine whether the duration of male nest attendance varied within the colony in relation to nesting density, yearly variation, and the laying phenology of females. We found that the average length of male attendance differed significantly between years and declined as the breeding season progressed. Small differences were also detected between observation plots, suggesting that the duration of male attendance was longer in areas of high nesting densities where the potential of EPCs was greatest. We also observed eider pairs interacting on the colony to determine if unattended females were more likely involved in aggressive interactions with lone males than pairs. Preliminary results follow predictions, where unattended females suffered more aggressive interactions with prospecting (lone) males whether walking or incubating, and that these interactions were greatest in areas of high nesting densities. To examine the behavioral ecology of male colony attendance, we recognized the need to acquire molecular evidence of extra pair paternity between nests with and without male attendance. We examined this by experimentally removing attending males from a random selection of eider nests in 2002 and 2003, to determine if male removal lowered the probability of hatch, while simultaneously increasing extra-pair paternity. We predicted that paired (control) females would experience greater reproductive success than experimentally widowed females, and that the paternity of eggs (no. of fathers) would increase among widowed birds. Results of this genetic analysis are ongoing, and will be discussed. 98 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005
Katherine Mehl¹ and Mark Gloutney² Ducks Unlimited Canada SECOND NORTH AMERICAN SEA DUCK CONFERENCE EAST COAST EIDER INITIATIVE ¹Ducks Unlimited Canada, 9 Bruce Street, Mount Pearl, NL A1N 4T3; kr_mehl@ducks.ca ²Ducks Unlimited Canada, P.O. Box 430, Amherst, NS B4H 3Z5 Ducks Unlimited Canada’s Eider Initiative is a five-year research initiative. The ultimate goal of this research is to develop a population model useful in guiding common eider (Somateria mollissima dresseri) harvest regulations and management decisions. We chose Newfoundland and Labrador as the focal point for this research because common eider populations in this region have experienced relatively little growth following their protection by the Migratory Birds Conservation Act, relative to populations throughout other portions of their range. To understand constraints to population growth requires a strong understanding of species-specific life history traits. This information is critical for developing and implementing management strategies that promote sustainable and harvestable populations. To reach this goal, we are using capture-mark-recapture techniques to estimate: 1) adult female survival, 2) seniority (proportion of experienced breeders in the population), 3) recruitment (proportion of first time breeders in the population), 4) local population growth rates, 5) breeding propensity (proportion of females breeding during any one season), 6) duckling survival, 7) sub adult survival; 8) age at first breeding, and lastly, 9) this research will use satellite telemetry to identify the links between breeding and wintering areas. Research sites include remote islands within Table Bay, located about 30 km SE of Cartwright, Labrador and islands near the Northern Peninsula, Newfoundland. During 2004, we banded a total of 1498 common eider ducklings (n=1079 and 419 in Labrador and on the Northern Peninsula of Newfoundland, respectively) and 180 adult females (n = 115 and 65 in Labrador and on the Northern Peninsula of Newfoundland, respectively). During 2004-2005, we received a total of 55 hunter band recoveries. All band recoveries were from eiders banded as ducklings along the shore of the Northern Peninsula, Newfoundland (n = 11) and Table Bay (n = 44). Ducklings banded in NL were shot in NL (n = 33), NS (n = 11), PQ (n = 5), St. Pierre et Miquelon (n = 5), and Maine (n = 1). We received no band recoveries of common eiders banded as adults in the same year. This research project is ongoing. NOV. 7-11, 2005 ANNAPOLIS, MARYLAND, USA 99
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