STRATEGIES INDIVIDUELLES D'HIVERNAGE CHEZ LA BECASSE DES BOIS Sco/opcrx rusticola

摘要

In order to survive throughout the winter, birds have to solve an adaptive trade-off between the need to feed and predator avoidance. In the case of Woodcock, this tradeoff is articulated around habitat selection. The risk of predation is higher in meadows used at night than in forests, but food biomass earthworms is ten times more abundant in meadows than in forests. Radio tracking highlighted two overwintering strategies. A third of Woodcocks remained in a unique site throughout the winter, whilethe rest visited several sites, alternatively or successively. The choice of strategy seems to depend on the foraging efficiency of each individual and their ability to escape predators. The use of meadows at night, which varies among individuals, provides another explanation to the starvation / predation trade-off. Most Woodcocks were active during the day in forest and at night in meadows, but some of them were completely diurnal and stayed in the forest at night. The decision to use meadows at night seemed to be taken every evening, depending on foraging success of during the day in the forest. Following a successful feeding day, in a good patch of food, the individual would not take therisk to fly to meadows. As the patch started to get depleted, the individual need could not be satisfied and it was forced to fly to meadows at night where there is always enough food and/or change its diurnal site. Therefore, the trade-off between feeding and predation risk depends on the efficiency of the individual at finding a good foraging patch in the forest and to exploit it optimally during the day.Mots eles: Becasse des bois, Hivernage, Predation, Habitat, Conservation.