Monitoring the abundance of mouflon in South France

Abstract

Monitoring change in the population size of mouflon (Ovis gmelini musimon × Ovis sp.) in rugged areas is an important yet difficult task for wildlife ecologists. To assess population change of mouflon inhabiting the Caroux-Espinouse massif, France, we compared a pedestrian and helicopter survey, using counts of animals as indices of abundance. Environmental factors such as date of survey and temperature affected the detection of mouflons from the ground and the air. Both indices were sensitive to observed changes in population size. A decrease in the pedestrian index was recorded in 1994, the year following an epizootic of keratoconjunctivitis, which markedly reduced the survival rate of mouflon. Variations in pedestrian index accounted for variations in harvests when excluding epizootic events. Both surveys detected a decrease in population size, which accounted for the recent increase of harvest. Helicopter and pedestrian surveys are reliable tools to monitor annually mouflons in mountainous areas. Simulations indicated that helicopter surveys should be preferred by managers because they provide the best trade-off between cost and precision.