Behaviour (activity budget, degree of terrestriality, intergroup sociality) and diet, and the impact of proximity to forest edge on both, were compared between two populations of ringtailed lemurs (Lemur catta) inhabiting rocky outcrop/anthropogenic savannah-surrounded forest fragments in south-central Madagascar. Both sites—a fragment in the Tsaranoro Valley local to Andringitra National Park, and a fragment at Anja Special Reserve, adjacent to National Route 7 in the Ambalavao area—are considered sacred forests (sites of human burial) by the local people living in these regions, and are therefore subject to traditional protective prohibitions (fady). Both sites attract tourists, but are managed differently, and the resources available to the L. catta differ between sites, affecting the behaviour of the lemur populations: L. catta at Tsaranoro spent more time feeding, and less time resting and engaging in social behaviour compared with those at Anja, where introduced fruiting trees were available and resource abundance appeared to be relatively higher. Also, L. catta at Tsaranoro were less edge-avoidant, with some groups travelling over 400 meters beyond outside the forest in order to utilize resources at the tourist establishment local to the site. L. catta at Anja were never observed more than nine meters outside the forest. Although the fragments are of similar size and were expected to differ little, many significant behavioural dissimilarities were observed, suggesting the importance of the refinement of rapid assessment techniques for judging the habitat suitability and conservational value of small forest fragments.