Reproductive Habits in the Snow Goose: The Influence of Female Age

Abstract

Parental age influences reproductive performance in several avian species. Clutch size increases and nesting becomes earlier after the first year of breeding in certain species (e.g., Great Tit (Parus major), Kluijver 1951; Blacklegged Kittiwake (Ra Canada Goose (Bruntu cunudensis muxha), Brakhage 1965). Other species show no effect of female age and, in a few instances, clutch size declines with age (see Klomp 1970). The correlation of parental age with hatching and fledging success shows similar variability among species. In many colonial nesting species, young birds establish territories in peripheral or marginal habitats (e.g. Coulson 1971) either because of their inferior competitive ability in acquisition of central nest sites (Coach 1958, WynneEdwards 1962) or because adults, nesting earlier, establish central territories by precedence ( Coulson 1971). The Lesser Snow Goose ( Anser cuerulescens caerulescens; Delacour 1954) has been under study at a small nesting colony (3,000 pairs) at La P&rouse Bay, Manitoba (58”24’ N 94”24’ W) since 1968. Many of the birds of this colony are individually identifiable through coded plastic leg bands. In this paper, we examine the age of females as a factor affecting the spatial distribution of nests in the colony, reproductive success and the timing of nesting. Annual differences in the proportion of young birds that nest are also examined. Male geese that hatch at La P&rouse Bay seldom return to the colony after reaching reproductive maturity (Cooke et al. 1975). We have, therefore, been unable to establish a population of banded males of known age and to examine the influence of male age on reproduction.