Arctic Climate, Spring Nutrition, and Recruitment in Midcontinent Lesser Snow Geese

Abstract

I examined fall age ratios of midcontinent lesser snow geese (Chen caerulescens) shot by hunters in the Central and Mississippi flyways (1962-1999), and spring nutrient reserves in southern Manitoba, Canada (Apr-May, 1983-1984, 1988-1993). Age ratios were inversely related (95%[β S ] = -0.170 ± 0.068) to severity of arctic weather as indexed by average snow depth during May and June, and mean June temperatures. After accounting for this effect, age ratios declined 0.017 ± 0.009 immatures/adults/year during 1962-1999. Body size, indexed by principal components analysis of 10 morphological measures, declined -0.082 ± 0.057 per year during 1983-1993. Body mass, fat, protein, and mineral reserves showed considerable annual variation, but only mass (9.8 ± 1.6 g/day) and body fat increased during spring staging in Manitoba; rate of increase in body fat ranged from 6.0 ± 2.9 g/day during 1990 to 17.5 ± 3.8 g/day during 1993. Using model-averaged estimates from a set of candidate models, fall age ratios (controlling for differences between flyways and annual severity of arctic spring weather) were related to body mass (0.0011 ± 0.0008 immature/adult/g), and fat during early staging during April (0.00092 ± 0.00072 immatures/adult/g), but the relationship with body fat during late staging in May was not as strong (0.00020 ± 0.00022 immatures/adult/g); age ratios were unrelated to variation in protein or mineral reserves. Linkages between recruitment in the Arctic and nutritional state on the prairies the previous spring suggest that management on spring staging areas could influence dynamics of the midcontinent population of lesser snow geese, and perhaps of other Arctic-nesting goose populations.