The effect of habitat patch connectivity on samango monkey (Cercopithecus mitis) metapopulation persistence

Samango monkeys inhabit the highly fragmented forests of the midlands of Kwazulu-Natal, South Africa. Not all forest patches are occupied and the survival of monkey populations in the face of further fragmentation provides the motivation for a theoretical consideration of metapopulation persistence under different management policy conditions. The primary aims of the model are to examine the influence of connectivity on metapopulation persistence and also to provide a temporal scale for metapopulation persistence in the case of this species. We develop a stochastic, spatial population model, in which we model edge and core troops in a patch separately, and take into account the effect of demographic and environmental stochasticity, as well as the impact of natural catastrophes. The effects of different levels of connectivity between forest patches are investigated, and we allow for a variable number of patches in the metapopulation. We compare the management options of reintroduction of troops and of providing corridor links between patches in a metapopulation. The model shows that neither management option has any meaningful effect on short-term (< 200 years) survival. In the long-term, however, corridors significantly improve metapopulation persistence. In the absence of interventive management to improve connectivity, samango monkey metapopulations (typically 8 forest patches) show poor persistence probabilities, less than 0.75 to 800 years and less than 0.34 to 1500 years. In contrast these survival probabilities are 0.9 to 800 years and 0.8 to 1500 years when connectivity is provided. The creation of corridors are of the utmost importance for the long term survival of the species.