Beth MacCALLUM, Chiarastella FEDER, Barry GODSALVE, Marion I. PAIBOMESAI, and Allison PATTERSON
CWBM 5 (2): 32-45.
Correspondence: Beth MacCallum, Bighorn Wildlife Technologies Ltd., 176 Moberly Drive, Hinton, AB, T7V 1Z1, Canada. Email: email@example.com
Prefledging waterfowl are vulnerable to an array of mortality agents and are often spatially restricted. Factors affecting habitat use by brood-rearing harlequin duck (Histrionicus histrionicus) females at the home range scale were investigated in the east slope of Alberta’s Rocky Mountains. Generalized linear models were used to assess the effect of environmental parameters on harlequin duck brood presence (n = 38) and brood absence (n = 38). A set of models were built a priori and subsequently ranked by Akaike Information Criterion (AICc). Models relating to foraging conditions indicated the probability of an area being used for brood-rearing increased with total invertebrate biomass.
Models relating to predator avoidance indicated the probability of brood use was high when percentage of channel overhang was close to 0, and declined with increasing overhang, shrub coverage in the 1st m, bank relief and more exposed bank. When models were combined, results suggested that predator avoidance had more support than foraging conditions. Comparisons between brood-rearing areas and spring foraging areas indicated that brood use areas had lower bank relief, less exposed bank, and higher invertebrate biomass than areas used for foraging in spring.
Comparisons of brood-rearing areas to nesting areas indicated that brood-rearing areas had less channel overhang and less shrub cover in the 1st m than nesting areas. We conclude that harlequin duck females select habitat for brood-rearing based on the ability to detect predators and the presence of habitat features that allow ducklings to avoid predators. At the home range scale, invertebrate biomass was important but not as important as predator avoidance features.
Key Words: Alberta, Brood-rearing, Habitat, Harlequin Duck, Histrionicus histrionicus.