Incubating birds must balance the time and the energy invested in incubation with the energy acquisition for their survival. Many factors such as weather and predation inXuence this trade-oV. In Arctic geese, only females incubate, and they leave the nest regularly to feed while males invest in keeping their nests and mates safe. This study conducted on Big Bird Island (Taïmyr Peninsula) during the summer of 2004 examined the incubation behavior of dark-bellied brent geese Branta bernicla bernicla to assess the eVect of date, period of day and weather conditions on the incubation and feeding behaviors of females and males. Females were at their nests only for 65% of the total time observed. This very low value, compared to other goose species, could be the result of the combined eVects of good weather conditions, low predation pressure and opportunities to feed close to the nest. We found diVerential adjustments of male and female behaviors. Females appeared to focus on the trade-oV between feeding and incubating, in relation to weather conditions, and on their own energy balance. Males appeared to respond primarily by the absence of the female from their nest.