Birth and death processes and the extent of dispersal directly affect population dynamics. Knowledge of ecological factors that influence these processes provides insight into natural selection and understanding about changes in population size. King eiders (Somateria spectabilis) breed across the arctic region of North America and winter in polar oceanic waters of the western and eastern regions of the continent. Here I studied a local population of King Eiders at Karrak Lake, Nunavut, where I used analysis of naturally-occurring stable isotopes (13C, 15N) from feathers, in conjunction with banding data, to investigate the extent of dispersal among winter areas and the influence of winter area on subsequent breeding. In addition, I used capture-mark-recapture methods to (1) investigate the relative contributions of survival and recruitment probabilities to local population dynamics, and (2) to test hypotheses about the influence of specific ecological factors on those probabilities or their components, e.g., nest success, duckling survival. Isotopic data suggested that female King Eiders were not strongly philopatric to wintering areas between years. Individuals that wintered in western seas initiated nests earlier and had slightly larger clutch sizes during early nest initiation relative to females that wintered in the east. Female condition during incubation did not vary by winter area. Female King Eiders of known breeding age were at least 3-years-old before their first breeding attempt. Age of first successful breeding attempt did not appear to be influenced by body size. However, after reaching breeding age, larger females apparently experienced greater breeding propensity. Adult survival rate (1996-2002) was estimated as 0.87 and recapture probabilities varied with time and ranged from 0.31 to 0.67. There is no evidence of survival advantages related to larger size. Population growth for this local study area was high, estimated at 20%/year with larger females contributing more to the population growth than smaller females. With continued population growth, density-dependent effects on components of recruitment appeared to emerge; the proportion of the female population that nested successfully declined with increasing population size. The probability of breeding successfully did not correlate with Mayfield estimates of nest success. To gain insight into King Eider brood ecology I, respectively, monitored 111 and 46 individually-marked ducklings from broods of 23 and 11 radio-marked King Eiders during 2000 and 2001. Total brood loss accounted for 84% of all duckling mortality with most brood loss (77%) less than 2 days after hatch. Estimated apparent survival rates of ducklings to 22 days of age were 0.10 for those that remained with radio-marked females, 0.16 for all ducklings, including those that had joined other broods, and 0.31 for broods. Ducklings brooded by larger females experienced higher survival than those brooded by smaller females, and ducklings that hatched earlier in the breeding season survived at higher rates. Overland brood movements of 1 km or more occurred in both years, and survival was greatest for ducklings that dispersed from Karrak Lake to smaller ponds than on Karrak Lake itself, the central nesting area. Estimates of duckling survival, combined with relative contributions to the population by adults, suggest that ecological factors such as body size can influence population growth. Furthermore, low duckling survival and delayed maturity, emphasize the need of high adult survival for population growth to occur. These data, in combination with evidence of dispersal among wintering areas have helped contribute to a broader understanding of North American King Eider demographics.

Birth and death processes and the extent of dispersal directly affect population dynamics. Knowledge of ecological factors that influence these processes provides insight into natural selection and understanding about changes in population size. King eiders (Somateria spectabilis) breed across the arctic region of North America and winter in polar oceanic waters of the western and eastern regions of the continent. Here I studied a local population of King Eiders at Karrak Lake, Nunavut, where I used analysis of naturally-occurring stable isotopes (13C, 15N) from feathers, in conjunction with banding data, to investigate the extent of dispersal among winter areas and the influence of winter area on subsequent breeding. In addition, I used capture-mark-recapture methods to (1) investigate the relative contributions of survival and recruitment probabilities to local population dynamics, and (2) to test hypotheses about the influence of specific ecological factors on those probabilities or their components, e.g., nest success, duckling survival. Isotopic data suggested that female King Eiders were not strongly philopatric to wintering areas between years. Individuals that wintered in western seas initiated nests earlier and had slightly larger clutch sizes during early nest initiation relative to females that wintered in the east. Female condition during incubation did not vary by winter area. Female King Eiders of known breeding age were at least 3-years-old before their first breeding attempt. Age of first successful breeding attempt did not appear to be influenced by body size. However, after reaching breeding age, larger females apparently experienced greater breeding propensity. Adult survival rate (1996-2002) was estimated as 0.87 and recapture probabilities varied with time and ranged from 0.31 to 0.67. There is no evidence of survival advantages related to larger size. Population growth for this local study area was high, estimated at 20%/year with larger females contributing more to the population growth than smaller females. With continued population growth, density-dependent effects on components of recruitment appeared to emerge; the proportion of the female population that nested successfully declined with increasing population size. The probability of breeding successfully did not correlate with Mayfield estimates of nest success. To gain insight into King Eider brood ecology I, respectively, monitored 111 and 46 individually-marked ducklings from broods of 23 and 11 radio-marked King Eiders during 2000 and 2001. Total brood loss accounted for 84% of all duckling mortality with most brood loss (77%) less than 2 days after hatch. Estimated apparent survival rates of ducklings to 22 days of age were 0.10 for those that remained with radio-marked females, 0.16 for all ducklings, including those that had joined other broods, and 0.31 for broods. Ducklings brooded by larger females experienced higher survival than those brooded by smaller females, and ducklings that hatched earlier in the breeding season survived at higher rates. Overland brood movements of 1 km or more occurred in both years, and survival was greatest for ducklings that dispersed from Karrak Lake to smaller ponds than on Karrak Lake itself, the central nesting area. Estimates of duckling survival, combined with relative contributions to the population by adults, suggest that ecological factors such as body size can influence population growth. Furthermore, low duckling survival and delayed maturity, emphasize the need of high adult survival for population growth to occur. These data, in combination with evidence of dispersal among wintering areas have helped contribute to a broader understanding of North American King Eider demographics.

Avian cholera, caused by infection with Pasteurella multocida, is an important infectious disease of wild birds in North America Since it was first confirmed in 2005, annual outbreaks of avian cholera have had a dramatic effect on common eiders on East Bay Island, Nunavut, one of the largest breeding colonies of northern common eiders (Somateria mollissima borealis) in the eastern Arctic. I investigated potential avian and environmental reservoirs of P. multocida on East Bay Island and other locations in the eastern Canadian Arctic by collecting cloacal and oral swabs from live or harvested, apparently healthy, common eiders, lesser snow geese, Ross’s geese, king eiders, herring gulls, and snow buntings. Water and sediment from ponds on East Bay Island were sampled before and during outbreaks. Avian and environmental samples were tested using a real-time polymerase chain reaction (PCR) assay to detect P. multocida. PCR positive birds were found in every species except for snow buntings, and PCR positive common eiders were found in most locations, supporting the hypothesis that apparently healthy wild birds can act as a reservoir for avian cholera. In all years, P. multocida DNA was detected in ponds both before and after the avian cholera outbreak began each year, suggesting that the environment also plays a role in outbreak dynamics. Contrary to our expectations, model results revealed that ponds were generally more likely to be positive earlier in the season, before the outbreaks began. Whereas average air temperature at the beginning of the breeding season was not an important predictor for detecting P. multocida in ponds, eiders were more likely to be PCR positive under cooler conditions, pointing to an important link between disease and weather. Potential origins of P. multocida causing avian cholera in Arctic eider colonies were investigated by comparing eastern Arctic isolates of P. multocida to isolates from wild birds across Canada, and the central flyway in the United States. Using repetitive extragenic palindromic-PCR (REP-PCR) and multi-locus sequence typing (MLST), we detected a low degree of genetic diversity among isolates, and P. multocida genotypes were correlated with somatic serotype. Isolates from East Bay Island were distinct from P. multocida from eider colonies in the St. Lawrence Estuary, Quebec, however, East Bay Island isolates were indistinguishable from isolates collected from a 2007 pelagic avian cholera outbreak on the east coast of Canada. Isolates from East Bay Island and Nunavik shared sequence types, indicating possible transmission of isolates among eider colonies in the eastern Arctic. Previously, feather corticosterone in eiders was found to be significantly associated with environmental temperature during the moulting period. In my study, path analysis revealed that environmental conditions experienced during the moulting period had direct impacts on arrival date and pre-breeding body condition of common eiders during the subsequent breeding period on East Bay Island, with indirect impacts on both reproductive success and survival. Higher temperatures experienced during the fall moulting period appear to impose significant costs to eiders, with subsequent carry-over effects on both survival and reproduction many months later during avian cholera outbreaks. This thesis describes several important features of the host, agent and environmental dynamics of avian cholera in North America with a particular focus on the disease in the eastern Canadian Arctic. Continued exploration of infectious wildlife disease dynamics is needed to better predict, detect, manage, and mitigate disease emergence that can threaten human and animal health and species conservation.