Light pollution and habitat fragmentation in the grey mouse lemur.

Light pollution, by changing organisms' behavior, affects locomotion, migration and can ultimately fragment the habitat. To investigate the effects of light pollution on habitat fragmentation, we conducted an experimental study on a nocturnal and photosensitive primate, the grey mouse lemur (Microcebus murinus). Twelve males were housed individually in an apparatus with two cages connected by two corridors, opaque and transparent. During 4 nights, the transparent corridor was illuminated by specific light intensities: 0 lx, 0.3 lx, 20 lx and 51.5 lx corresponding respectively to total darkness, full moon, minimal intensity recommended by the European standard EN-13201 on public lighting, and to light pollution recorded in an urban area. Each night, general activity, use of corridors and cage occupancy were recorded using an infrared camera. For the first time in a nocturnal primate, results demonstrate that light pollution changes the preference of use of corridors, modifies the locomotor pattern and limits the ability of animals to efficiently exploit their environment according to a light intensity-dependent relationship. However, results indicate that a dark corridor allows partial compensation partly preserving general activities. This study highlights the necessity to consider light pollution during the implementation of conservation plans and the relevance of nocturnal frames.