 Slow lorises range across tropical and subtropical regions and are found in primary and secondary rainforests , as well as bamboo groves and mangrove forests . They prefer forests with high , dense canopies , although some species have also been found in disturbed habitats , such as cacao plantations and mixed @-@ crop home gardens . Due largely to their nocturnal behavior and the subsequent difficulties in accurately quantifying abundance , data about the population size or distribution patterns of slow lorises is limited . In general , encounter rates are low ; a combined analysis of several field studies involving transect surveys conducted in South and Southeast Asia determined encounter rates ranging from as high as 0 @.@ 74 lorises per kilometer for N. coucang to as low as 0 @.@ 05 lorises per kilometer for N. pygmaeus . 
