Fragment and life-history correlates of extinction vulnerability of forest mammals in an urban-forest mosaic in EThekwini Municipality, Durban, South Africa

Nestedness refers to a species distribution pattern whereby species found in species-poor sites represent a subset of those in species-rich sites. Nestedness is presumed to be primarily a result of selective extinction of species and thus is important for determining mechanisms of species impoverishment in fragmented landscapes. In this study, we investigated the effects of forest fragment attributes and species' life-history traits on nestedness patterns of terrestrial mammals in an urban-forest mosaic in EThekwini Municipality Area, Durban, South Africa. A presence/absence matrix of mammals (16 species) in forest fragments (28 fragments) was compiled based on the mammalian survey conducted using remote-triggered camera traps. The mammalian assemblage in the study area displayed significant nestedness. The nested ranking of forest fragments was strongly correlated with fragment area and proximity index but not with shape index and foliage height diversity. The best model based on Akaike Information Criterion (AIC(c)) showed that among species' life-history traits, body mass, trophic level, niche breadth and sociality were the most suited as predictors of extinction vulnerability. In particular, niche breadth was strongly associated with extinction vulnerability. Thus, the ability to persist in forest fragments of various sizes as well as the ability to move to fragments with different degrees of isolation shape fragment dynamics in this landscape. Furthermore, species with broad resource requirements are more likely to persist with further habitat disturbance. Overall, this study showed the importance of integrating forest fragment attributes and ecological traits of species in nestedness analyses for determining species in most need of conservation action which is important for preventing further loss of species.