What do we know about the effect of patch size on primate species across life history traits?

Habitat loss and fragmentation are significant threats for primate species worldwide. However, few attempts have been made to look for general patterns in primate responses to habitat loss and fragmentation, or whether these may be associated with species' traits. We conducted a review of published literature on effects of patch size to quantify the effect of a reduction in this predictor on primates, and to determine whether these effects depend on species' traits. The effects of patch size on seven response variables (density, parasite prevalence and diversity, presence, genetic diversity, time spent feeding, resting and movement), were extracted from 135 papers and compared across six species traits (diet specialisation, social structure, body size, home range size, group size and dispersal ability). We found that density, parasitic prevalence and diversity and time spent feeding were positively associated with a reduction in patch size, while species' presence and genetic diversity were negatively associated. Time spent resting and moving did not show clear patterns. We found little evidence that the effect of patch size varies consistently with traits. This study provides important evidence for the consistent effect of patch size on a range of factors that influence the dynamics of primate populations. However, there is a need to move beyond quantifying patch size effects alone and to quantify the effects of changes occurring at broader landscape scales. This would allow more holistic primate conservation strategies to be developed across whole landscapes rather than being focussed on the management of individual patches.