I examine the niche partitioning between native ring-tailed lemurs, Lemur catta, and
an introduced hybrid brown lemur population of Eulemur rufus x E. collaris in Malaza
gallery forest of Berenty reserve, in comparison with the natural sympatric population
of ring-tailed lemurs and red collared brown lemurs, Eulemur collaris, in
Ambatotsirongorongo forest and with allopatric ring-tailed lemurs at Bealoka forest,
in order to determine the impact of the introduced brown lemur population at Berenty
reserve on the behaviour and distribution of native ring-tailed lemurs. Behavioural
observations were conducted from September 2008 to December 2009; lemur
population survey was conducted from 2005 to 2009. Behavioural sampling methods
include scan group sampling, focal animal sampling and ad libitum of social
behaviour and feeding behaviour. Two groups of each lemur species were followed
in Malaza Berenty forest, one group of ring-tailed lemurs in Bealoka forest and one
group of each lemur species was followed in Ambatotsirongorongo forest. Vegetation
study was conducted in Bealoka and Berenty forests, whereas preliminary data on
vegetation structure was already available for Ambatotsirongorongo. At Berenty
reserve, the dynamic of the native ring-tailed lemur population was conditioned by
food availability and habitat quality. The brown lemur growth and distribution appear
to be affected by the water availability. Individual energy demands for various activity
rhythms play a big role in brown lemurs' ecology. Food availability, hierarchy and
territory are the main niche dimensions that shape ring-tailed lemurs' ecology. Niche
partitioning between native population of ring-tailed and collared brown lemurs at
Ambatotsirongorongo forest relies mainly on habitat use. Feeding ecology of ringtailed
lemurs in Bealoka forest is dominated by fruits. Habitat utilization differs
markedly from both Berenty and Ambatotsirongorongo forest. Changes in ring-tailed
lemurs' behaviour and distribution at Berenty reserve are partly due to the
competition with the introduced brown lemurs. This situation has resulted in a niche
partitioning between both species by creating a bimodal niche for ring-tailed lemurs:
the marginal habitat and the closed canopy forest. The comparisons with ecological
mechanisms and evolution of Bealoka and Ambatotsirongorongo forests show that
Berenty has shifted from a situation more like Bealoka's to a situation more like
natural sympatry