Edge Effects on the Behaviour and Ecology of Propithecus coquereli in Northwest Madagascar

The energy frugality hypothesis states that in response to Madagascar’s unpredictable habitat, lemurs should adopt strategies of energy optimization. I have applied this hypothesis to lemur behavioural ecology in response to forest edges. I compared two groups of Propithecus coquereli living less than 1-km from a forest edge with two groups living greater than 1-km from the edge in Ampijoroa forest station, Ankarafantsika National Park, NW Madagascar. Edge effects in Ampijoroa penetrated up to 625-m into the forest. Propithecus coquereli were edge avoiders, with 94.54% of sightings of Propithecus coquereli found outside of the area of edge influence. There was no difference between group ranges for density of food trees, however tree diameter at breast height (dbh) and tree height did differ between groups. These habitat differences did not neatly divide edge versus interior groups, but appeared to be more nuanced. I found no differences between groups for activity budgets, food quality, or spatial patterns of plant species/ parts consumed. However, groups nearer to the edge had home ranges that were more than double in size to interior groups. Groups in the interior had higher group-specific densities and more frequent intergroup encounters which may have led groups to adopt smaller ranges to avoid expending energy in intergroup encounters. More evidence of human impact was found in the edge, therefore groups near the edge might also range further to avoid humans. Groups showed differences in the spatial pattern of behaviours, activity by age-sex category, substrate size and vertical location used while traveling, and dietary overlap. However, these differences may not be reflective of distance to the forest edge - all groups avoided the edge - but instead may reflect subtle differences in habitat structure between the four groups.Ph