Body size and age of recruitment in Snow Geese Anser c. caerulescens

'At what age to start breeding?' is a question fundamental to analysis of l ife histories. While there has been considerable interest in the theoretica l aspects of age of first breeding, comparatively little work has been done on the problems of estimating recruitment rates in wild populations. Most studies to date have relied on ad hoc methods that rely on one or more assu mptions which may be generally untenable. Recently, it has been suggested t hat mark-recapture analysis can provide a robust, statistically formal appr oach for the analysis of recruitment, by using 'reverse capture-histories' to estimate the probability of entering the population over a given interva l. We applied this approach to data from the arctic-breeding Lesser Snow, G oose Anser c. caerulescens, using data from a long-term study in subarctic Canada. We tested the hypothesis that recruitment rate in this species tons influenced by structural size. Since arctic-nesting geese rely heavily on endogenous nutrient reserves for reproduction, structurally smaller birds m ay be less able to recruit at a young age than larger birds. However, despi te significant long-term changes in body size, and significant annual varia tion in recruitment rate, we found no evidence of correspondence between th e two.