Behavior and ecology of three sympatric bamboo lemur species (genus Hapalemur) in Ranomafana National Park, Madagascar

Ecological theory posits that sympatric species should differ in resource use to facilitate coexistence. To investigate resource partitioning among closely related sympatric species, I conducted the first long-term (September 1996–December 1999) study of Hapalemur g. griseus (0.9 kg), H. aureus (1.5 kg), and H. simus (2.5 kg) in Ranomafana National Park, Madagascar.; H. g. griseus lives in small but flexible social groups with ≤2 breeding females. Its home ranges average 15 ha. H. aureus forms family groups of ≤4 individuals and occupies home ranges of 26 ha. H. simus is polygynous and its home range size is 62 ha. Bamboos and grasses represent over 88% of all three lemurs' diets. H. g. griseus has the most flexible diet and consumes more non-bamboo foliage and fruit than H. aureus or H. simus. H. simus relies almost exclusively on bamboo, particularly Cathariostachys madagascariensis, eating shoots in the summer and culm pith in the winter. All three Hapalemur species consume cyanogenic shoots. Moreover, H. simus selects significantly larger shoots than the two congeners.; To understand the lemurs' digestive strategy, I examined their digesta transit time (TT). Contrary to body size expectations, H. g. griseus has the longest TT and H. simus has the shortest TT.; While H. g. griseus and H. aureus are diurnal and use their entire home ranges weekly, H. simus is cathemeral and shows intense use of core areas. Also, H. simus is significantly more terrestrial than the two sister taxa.; H. g. griseus and H. simus mate in May–June and H. aureus mates in July–August; the gestation lengths are 137, 149, and 138 days, respectively. Females of all three species produce singletons; they are the primary caretakers. H. aureus females nest their infants in dense foliage during the first 10 to 14 days. Like H. g. griseus, H. aureus parks and orally transports its infants but H. simus does not.; Findings of this study show that body size is a major constraint and affects the behavior and ecology of the three sympatric Hapalemur species. Finally, differences in the lemurs' life history further differentiate their ecological niches.