LIFE HISTORY STUDIES OF THE LESSER SNOW GOOSE (ANSER CAERULESCENS CAERULESCENS). IV. THE SELECTIVE VALUE OF PLUMAGE POLYMORPHISM: NET VIABILITY,THE TIMING OF MATURATION,AND BREEDING PROPENSITY

Cooch (1961, 1963) suggested that changes in the genotypic composition of snow goose colonies comprising the Hudson Bay-Foxe Basin population could be attributed to selection favoring the blue phenotype. In the preceding paper (Cooke et al., 1985), we examined potential differences in net fecundity between the two phenotypes at La Pérouse Bay in northern Manitoba. No substantial differences in any component of fecundity were detected. In the present paper, we examined potential differences in pre-reproductive and adult viability, age of maturation, and breeding propensity. Again, no differences associated with the plumage polymorphism were detected in any of these life history characteristics. Thus, despite a thorough analysis of the complete life cycle, we were unable to uncover any evidence supporting a selection hypothesis for the persistence and dynamics of this conspicuous polymorphism. An alternate hypothesis based primarily on gene flow and assortative mating appears more plausible.