Regulation of incubation behavior in Black Brant

Abstract

We assessed the influence of climatic, environmental, and biological factors on nest attentiveness of female Black Brant (Branta bernicla nigricans). Within females, nest attentiveness varied significantly with time of day, rainfall, ambient temperature, incubation day, and (incubation day)2. We examined variation among females in individual investment in reproduction by comparing the amounts of nutrients invested in the clutch with those invested in incubation. We compared nest attentiveness with the amount of nutrient reserves available to test the hypothesis that a trade-off exists between nutrient investment in eggs and investment in incubation. Among females, nest attentiveness was lower in 1992 (mean = 82%) than in 1993 (mean = 87%) and increased with clutch volume and mass. Our results show that environmental conditions influence incubation behavior in Black Brant. We detected a trade-off between investment in eggs and nest attentiveness, but the results are also consistent with the hypothesis that females vary in individual quality and this variation influences egg production as well as incubation.