Comparing migration ecology among geographically distinct populations of Canada Geese (Branta canadensis) and Cackling Geese (Branta hutchinsii).
Migration timing is important to the reproductive success of birds, as mismatches with peak food abundance can lead to reduced fitness and population declines. Birds breeding at northern latitudes may be more susceptible to the effects of climate change, as narrower seasonality farther north can result in timing mismatches for birds that may rely more on endogenous cues to migrate. Few studies have used direct-tracking methods on waterfowl to compare differences in migration ecology across a latitudinal gradient. Spatiotemporal tracking data can also be useful for conservation and management of waterfowl. Giant Canada Geese (Branta canadensis maxima) are increasing in numbers, to the point where they are declared overabundant. Special hunting seasons may be opened to increase harvest of this subspecies, but care must be taken to avoid non-target goose populations. My first objective was to use direct-tracking data to examine differences in migration timing and rate between three goose populations: giant Canada Geese, Southern Hudson Bay Canada Geese (B. c. interior), and Cackling Geese breeding across a broad latitudinal range (49-65 degrees). My second objective was to apply my findings in relation to conserving and managing overabundant Canada Geese, and whether spring migration in overabundant Giant Canada Geese and less abundant Cackling Geese overlap with the proposed spring hunting season (March 1 to March 31). I found that southern-breeding geese migrated earlier and with more variation in spring compared to more northern-breeding geese, and in fall the northern-breeding geese migrated earlier compared to more southern-breeding geese. I also found that all three goose populations were in Manitoba during the fall hunting season, and about 9% of Giant Canada Geese were in Manitoba during the proposed spring hunting season. Increasing our knowledge of migration ecology in waterfowl can be useful in conservation of species that may be susceptible to the effects of climate change, or managing species that are increasing in numbers in which timing data can aid decisions to open special hunting seasons to increase harvest rates.
Biology, Bird migration, Canada Goose, Cackling Goose, Waterfowl management, Phenology