Factors affecting population dynamics of Eurasian woodcocks wintering in France: assessing the efficiency of a hunting-free reserve
Résumé
The Eurasian woodcock Scolopax rusticola is a migratory bird of major importance for hunting, which is susceptible to habitat loss and the stochastic effects of severe winter weather. Conservation issues mostly concerned regulation of hunting, but the efficiency of hunting-free reserves has never been investigated. We studied causes of mortality and survival probabilities of 98 radio-tagged woodcocks in a reserve with no hunting and in an adjoining hunting area in Brittany (France). Predation, mostly by mammalian predators on fields at night, was similar among adults and yearlings, while hunting mortality was more important in yearlings. Overall winter survival probabilities were 0.86 ± SE 0.07 in adults and 0.63 ± SE 0.07 in yearlings. Survival probabilities of both age classes increased as birds spent more time in the reserve. Equality of predation in both reserve and hunting areas suggests an additive mortality due to hunting over the winter. Population matrix models predicted that such low survival probabilities cannot sustain long term viable populations. These results call for caution in the harvesting of woodcock populations wintering in western France and could be a forewarning of a decline. The regulation of hunting by setting bag limits or reducing the length of shooting seasons, or the creation of reserves might be appropriate tools for the sustainable management of woodcock populations.