It roosts in caves well beyond the twilight zone (MacKinnon et al. 2003). Few colonies are known to biologists even in areas with extensive underground cavities (MacKinnon et al. 2003, Kofoky et al. 2007) suggesting that they have specific roosting requirements (Andrianaivoarivelo et al. 2011a). It is also recorded from a number of locations that are without known roosts or caves (Andriafidison et al. 2006, Rakotoarivelo and Randrianandriananina 2007, Rakotonandrasana and Goodman 2007) and it may therefore roost in other sites such as tree holes.

Although it is widely distributed it appears to be associated with forests (MacKinnon et al. 2003), is able to fly within relatively intact forest (Kofoky et al. 2007) and has been trapped inside Eucalyptus plantations (Randrianandriananina et al. 2006), in agricultural settings (Andrianaivoarivelo et al. 2011b, Randrianandriananina et al. 2006, Kofoky et al. 2007, Rakotoarivelo and Randrianandriananina 2007, Ralisata 2014) and in villages (Andriafidison et al. 2006).

There have been several dietary studies. It feed on the fruit of endemic forest trees (Razafindrakoto 2006). Nectar appears to be an important dietary constituent and bats have been observed feeding on banana and kapok flowers (Andrianaivoarivelo et al. 2011b, Andriafidison et al. 2006). In the Maromizha forest in eastern Madagascar, Andrianaivoarivelo et al. (2011b) found relatively few seeds (several Ficus species, Dypsi ssp and Rubus mollucanus) in the faeces and inferred that R. madagascariensis fed also on nectar, flowers, leaves and fruit with seeds too large to swallow. Flight cage experiments by Andrianaivoarivelo et al., (2102b) revealed that it preferred native or introduced fruit of no commercial value (F. polita, Syzigium jambos and S. malaccense) to commercial species (Litchi chinensis and Diospyros kaki). In similar experiments, bats were offered F. sakalavarum and Ziziphus jujube. Juveniles fed extensively on the former while adults preferred unripe Ziziphus, whose seeds are too large to swallow. It was concluded that R. madagascariensis is an effective disperser of F. sakalavarum particularly for isolated trees or those in forest fragments where other frugivores are rare (Andrianaivoarivelo et al. 2012a).

Rousettus madagascariensis feeds especially on autochthonous or introduced plant species which grow inside or outside the natural forest ecosystems (Andrianaivoarivelo et al. 2012a, Andrianaivoarivelo et al. 2011b, Andriafidison et al. 2006). It appears to have no predators when foraging, but the barn owl (Tyto alba) is a predator at roost sites (Goodman and Griffiths 2006). Its feeding behavior seems to be well adapted to the anthropogenic changes of the environment and it contributes to the dispersion of forest seeds (Andrianaivoarivelo et al. 2011b).

The morphometric variations of this species are associated with sexual dimorphism and with geographical and altitudinal locations. The body mass also varies with food availability which in turns depends on season. However there was contrast between the morphometric and genetic diversities. Populations sampled at low altitude and in the North have a longer forearm and lower body mass than those at higher altitude, in the South and East of Madagascar. However, molecular genetic studies of samples from throughout Madagascar showed that there was no genetic variations between populations and the species has a panmictic structure (Andrianaivoarivelo 2012, Goodman et al. 2010). The lactation period coincides with the rainy season and weaning is completed by the end of the rain period. The growth of young bats takes place during the dry season and somatic growth is completed within a year (Andrianaivoarivelo 2012).

This species is endemic to Madagascar and the adjacent islands Nosy Be, Nosy Komba and Sainte Marie. It is generally widespread but rare or absent from the central highlands and the arid south-west (MacKinnon et al. 2003, Goodman et al. 2005).

As a game species under Malagasy law (Durbin 2007), R. madagascariensis is only protected when it occurs in nature reserves. In a survey of western Madagascar it was found in six protected areas: Parcs National d’Ankarana, Ankarafantsika, Namoroka, Tsingy de Bemaraha, Isalo and Réserve Spéciale d’Analamerana (Goodman et al. 2005). Roosts within existing protected areas should receive close attention from park staff to discourage hunting. Other roosts need to be conserved and this might be best achieved through their inclusion within new protected areas and with the cooperation of local communities.