Survival and Recruitment among Non-Migratory Canada Geese (Branta canadensis): Influence of Gosling Sex, Hatching Date, Mass at Fledging, and Family Type

Abstract

Among some Arctic-nesting geese, mass at fledging impacts first-year survival and recruitment into the breeding population, but this might not be true for temperate-nesting geese. For 25 years, we examined what variables impacted survival and recruitment of 731 Canada Geese (Branta canadensis) fledglings raised in Connecticut, USA by tracking individually marked birds throughout their lives. At fledging, the number of females (391) were similar to males (340), but by the end of the first year of life, females (247) outnumbered males (187). This can be explained due to the apparent survival rates for juvenile females (0.63) being higher than for males (0.55). Dispersal rate from natal areas were similar for males and females during the first year of life and cannot account for why females outnumbered males after one year of life. Apparent survival rates of female fledglings to the end of the second year was 0.48. For the 247 females still alive at the end of their first year of life, 190 were still alive at the end of their second year of life, yielding a 0.77 apparent survival rates during their second year of life. Sex was the only variable that explained the survival of fledglings until the end of their first year of life. The probability of females surviving the second year of life was not influenced by hatching date, fledging age, fledging mass, or family type. Heavier females at fledging were more likely to be recruited into the breeding population than lighter ones. Our results indicate that while an inability to acquire sufficient mass as a gosling does not affect survival, it impacts the ability to be recruited.