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The addition of eggs to a nest by a conspecific is known for approximately 250 bird species. Understanding the evolution of conspecific brood parasitism (CBP) requires assessment of fitness consequences to the egg recipient (host). We addressed host traits and the effects of CBP on future reproduction (i.e., annual survival) and hatching success of hosts by following the nesting of 206 red-breasted mergansers (Mergus serrator) for a colony in which an average of 41% of nests was parasitized annually. Each host was tracked for ≥2 seasons and up to seven seasons. The proportion of a host’s nesting attempts that was parasitized averaged 43% and varied considerably across individuals (range 0%–100%). Probability of parasitism, however, was not repeatable across a host’s nests. Rather, rates of CBP throughout a host’s lifetime increased with earlier dates of nest initiation. CBP had no effect on annual survival of a host. Hatching success throughout a host’s lifetime declined with a greater number of foreign eggs added to the individual’s nests. This study revealed that there may be measurable costs of CBP to lifetime reproductive success in red-breasted mergansers, although our observations suggest that costs to hosts are limited to the most heavily parasitized clutches.

Annual banding programs have allowed the estimation of key demographic parameters for many populations of harvested wildlife, yet they often provide little insight into vital rate variation among seasonally occupied habitats or among regions with differing hunting regulations. For lesser snow geese (Chen caerulescens caerulescens) in the midcontinent of North America, rapid growth in abundance and the consequent implementation of special conservation measures present a scenario where seasonal mortality estimates would be highly valuable. We evaluated variation in hunting mortality of adult and young geese among 3 seasons (autumn, winter, and spring) based on annual banding data from breeding colonies north and south of 60°N latitude, and seasonal hunting recoveries from the United States and Canada. Using band‐recovery models and data covering 1999 through 2015, we first estimated annual survival for geese of both age classes and breeding locations, and then subsequently used seasonal hunting recoveries to derive estimates of seasonal hunting mortality and annual non‐hunting mortality. Simulation models validated the accuracy of this approach. Hunting mortality in winter generally exceeded that during spring and autumn, but our estimates suggested that hunting mortality represented a small fraction of annual mortality for adult and young birds. Consistent with recent studies, our estimates pointed to a greater harvest effect for the smaller subarctic population breeding near southern Hudson Bay, Canada, than for the large arctic population breeding farther north. Although mean kill rates were higher for young than adult geese, natural mortality for young was high and temporally variable, implying that some hunting mortality experienced by young geese during their first year could be compensated by natural causes of death. Natural (non‐hunting) mortality and annual survival showed greater temporal variation than seasonal kill rates in adults and young geese, highlighting the importance of non‐harvest factors (e.g., climate, habitat, population density) to the dynamics of these populations. These novel estimates of seasonal kill rates and non‐hunting mortality contribute further support to the notion that internal dynamics of the lesser snow goose midcontinent population, including natural mortality and recruitment, currently influence population trajectory more than ongoing interventions through harvest management. © 2017 The Wildlife Society. In the context of ongoing management of overabundant lesser snow geese, we used band‐recovery data from 1999–2015 to estimate annual survival and derive estimates of seasonal hunting mortality and annual non‐hunting mortality. Non‐hunting mortality and annual survival were more variable than seasonal kill rates for adults and young geese, highlighting the importance of non‐harvest factors (e.g., climate, habitat, population density) to the dynamics of these populations.

AbstractChanges in harvest rate over the past 3 decades have been shown to be closely related to population growth of greater snow geese (GSG; Chen caerulescens atlantica). We used band-recovery and harvest survey data from 1970 to 2001 to study temporal variations in geographic harvest distribution and composition of GSG in Québec, Canada and the Atlantic Flyway states (AF) in the United States. We sought to determine whether (1) geographic variation in harvest was associated with temporal trends in total harvest rates observed during this period; (2) spatiotemporal distributions of harvest varied with age and sex; and (3) harvest distribution and composition differed between the spring conservation harvest initiated in 1999 and the regular fall hunt in Québec. We detected over time a gradual spreading in the geographic distribution of the fall harvest from the upper St. Lawrence estuary toward southwestern Québec. During winter, a sudden northward shift in the distribution of the United States harvest in the mid-1980s was associated with a high concentration of geese in mid-Atlantic Flyway states (Maryland, Delaware, and New Jersey), possibly due to short-stopping during migration. We argue that this led to a reduction of hunting pressure on GSG and may have contributed to the sudden decline in harvest rate that occurred at that time and ultimately to the ensuing population increase. We observed a decreasing proportion of juveniles in the kill throughout the hunting season within fall staging grounds in Québec and between Québec and the United States. We also found a much higher proportion of adults in the spring harvest than in the fall that is consistent with the conservation goal of increasing the adult harvest. We recommend that management actions focus on increasing harvest in mid-Atlantic Flyway states if further control of population growth is desired.