Résumé
The grey partridge Perdix perdix used to be a common and widespread species throughout the temperate zone of western Eurasia, but its populations have markedly declined in most parts of its native range since the 1950s. The Pyrenean subspecies P. p. hispaniensis is threatened by alteration of its habitat, and despite ecological and hunting interest in this subspecies, the impact of harvest on population sustainability remains largely unknown. We assessed mortality of Pyrenean grey partridge and its influence on the population growth rate during 1992-2001 in the French Pyrenees. Cause-specific mortality rates were estimated using multistate capture-recapture models based on fates of 67 radio-equipped birds. Annual recruitment was estimated as the ratio of juvenile birds to adult birds in harvested samples. Mammalian predators and raptors were each responsible for a 5% monthly mortality rate. At the peak of hunting activity (i.e. October), hunting was responsible for a 30% mortality rate in some years. Modeled population growth rates appeared stable without hunting but negative with hunting. The estimated difference in population growth rates under the two regimes was 0.46. Our estimates of population growth suggest that the population was decreasing during our study, whereas it appeared stable based on ground counts. We discuss this discrepancy and proposed management actions.