PARENT SESSION
Poster Session 28: Avian Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Reconstituted families and suburban lifestyles: Brood-rearing by giant Canada Geese in southern Quebec.
Doiron, Madeleine*,1, Giroux, Jean-François1, 1 Université du Québec à Montréal, Montreal, Quebec, Canada
ABSTRACT- Giant Canada Geese (Branta canadensis maxima) began to breed in southern Quebec in 1992. This population is increasing rapidly and could eventually become overabundant, bringing about problems for humans. The main objectives of this study were to determine the effects of habitat, hatch date and year on gosling growth and to evaluate the potential of brood-rearing habitat as a limiting factor for the growth of this population. During the summer 2004, we monitored adult females equipped with radio-transmitters or conventional alpha-numeric collars to determine habitat used by broods. In 2003 and 2004, we marked goslings at hatch and recaptured them a few weeks before fledging so they could be measured and weighted. Our observations showed that broods formed several large family groups (up to 190 individuals). The majority of females abandoned their young early in the summer, and 73% of recaptured goslings were reared by adults other than their biological parents. Broods used both anthropogenic habitats (i.e. lawns, agricultural fields) and natural habitats (i.e. islands, marshes). Once a brood-rearing site was chosen, there was little movement among sites or habitat types. Goslings reared predominantly on lawns had higher structural size and body mass than goslings reared largely in natural habitats. There were no annual (2003 vs. 2004) or seasonal (early- vs. late-hatched) variations in body mass or structural size of goslings, and male goslings had larger structural size and mass than female goslings in both years. These results suggest that geese benefit from the presence of anthropogenic habitats such as fertilized lawns which are abundant in suburban areas, though we lack data on food quality and availability to confirm this hypothesis. Shortages of suitable brood-rearing habitat will probably not limit the growth of this newly-established population in the near future.
Key words: Canada goose, brood rearing, growth rates, brood amalgamation