Impacts of mosquitoes and black flies on defensive behaviour and microhabitat use of the North American porcupine (Erethizon dorsatum) in southern Quebec

Biting flies are known to influence the behaviour and microhabitat use of certain mammals. However, most studies were realized in open habitats. Our objective was to determine if mosquitoes (Culicidae) and black flies (Simuliidae) affect the behaviour and habitat use of a mammal typical of the boreal forest, the North American porcupine (Erethizon dorsatum (L., 1758)). The project was divided into three parts: (1) abundance of biting flies and their (2) direct effects (bites) and (3) indirect effects (repelling movements and microhabitat use) on porcupines. The abundance of insects was measured with CO2-baited traps. Ten male porcupines were followed by telemetry. Mosquitoes were more abundant on the ground than in the tree canopy and the opposite was observed for black flies. The biting flies were less abundant inside dens than outside. The quantity of bites on porcupines was correlated with the abundance of black flies. We observed frequent repelling movements that were associated with the presence of insects. Some microhabitats offered excellent protection against biting insects, but porcupines did not use these refuges to a greater extent at the peak of insect abundance. We conclude that, although biting flies had measurable impacts on the wounding rate and behaviour of porcupines, this did not translate into important shifts in habitat use.