Impact of fosa (Cryptoprocta ferox) predation on the diademed sifakas
(Propithecus diadema) population in the Betampona Strict Nature Reserve,
Madagascar.
Abstract
Large-bodied mammals living in fragmented habitats are at higher risk of
extinction, and such risk can be influenced by ecological factors such
as predator-prey system dynamics. These dynamics can be particularly
complex for conservation management when one endangered species is known
to prey on another endangered species within the confines of isolated or
poor-quality habitats. Here we describe predation events observed over
19 months involving two threatened species: the largest carnivore found
in Madagascar, the fosa (Cryptoprocta ferox), and three groups of
diademed siafaka (Propithecus diadema) in the Betampona Strict Nature
Reserve. This site is a 22 sqkm low-altitude rainforest surrounded by
agricultural land and isolated from larger forest corridors; the
consequences of predator-prey dynamics can have important implications
for conservation at this site. We report five direct observations of
fosa predation attempts, of which one was successful, the discovery of
the body of a sifaka with evidence of fosa predation, and the
disappearance of three individuals. We describe the attacks and compare
the sifaka activity budgets and movement patterns before, during, and
after the events. The sifakas’ strategy to escape the predator is
fleeing short distances, hiding, and remaining vigilant. Our
observations suggest that fosa predation impacts the survival and
reproduction of diademed sifakas in Betampona. The impact of predation
on the diademed sifaka population of Betampona, combined with low
reproductive rates and potential high inbreeding due to the isolated
condition, can have important consequences on the survival of this
species at this site. Given the compounding effects of habitat isolation
and high hunting pressure, conservation management plans should
incorporate predator-prey dynamics by assessing estimates of prey and
predators’ population densities over time, as well as quantify the
incidence of predation pressure on prey population to devise effective
conservation strategies at the community level.