A recent study examined the daytime and nighttime activity patterns of two populations of tree-dwelling lemurs -- the first living in a rain forest, where tree canopy cover is consistent year-round, and the second living in a deciduous forest, where many trees lose their leaves during the winter months  Both groups of lemurs were found to be more nocturnal during winter months than they were the rest of the year
However, the winter increase in nocturnal activity was significantly more pronounced for the population living in the deciduous forest than it was for the population living in the rain forest
The primary predators for both lemur populations are high-flying birds that rely on their eyesight to hunt prey during daylight.