Reproductive Ecology of Emperor Geese: Annual and Individual Variation in Nesting

I studied the nesting ecology of adult female Emperor Geese (Chen canagicus) from 1982-1986 on the Yukon-Kuskokwim Delta (YKD), Alaska. I evaluated variation among and within years in date of migration, nest initiation date, clutch size, nesting success, and nesting frequency of 90 individually marked females. Geese arrived on their nesting areas at the same relative date of the season each year and initiated nests five days after their arrival on the study area. Individuals initiated nests at the same relative time of the season each year. There was no significant repeatability for clutch size, nor did mean clutch sizes vary among years. This may be related to geese having ready access to foods during spring migration and a relative short distance (600 km) between migration staging areas and nesting grounds. When data were pooled, clutch sizes declined as the season progressed; however, this decline was not significant within individuals among years. The proportion of adult females that nested annually varied from 38.5-52.0%; the probability of nesting was independent of clutch size or nesting success the previous season. This low nesting frequency may reflect high annual mortality resulting in a high proportion of newly paired birds each year (thus less likely to nest). Emperor Geese remain at food-rich, spring staging areas until nest sites are available, initiate nests early, lay large clutches, and frequently forgo nesting.