Small patches have high conservation value for primates

Small habitat patches are commonly overlooked in conservation. This is partly due to the legacy of the SL > SS principle that few (or a Single) Large patches (SL) should protect species more effectively than Several Small patches (SS) of the same cumulative total habitat amount. Although most empirical studies have found either the reverse (SS > SL) or no difference (SL = SS), the original SL > SS principle is still widely assumed to be valid and particularly so for threatened taxa, such as most primates. Here, we tested the SL > SS principle using global data of primate patch occupancy in 1791 forest patches from 50 primate studies. We collated patch occupancy data across combinations of patches, and we evaluated whether combinations of SL patches have higher or lower primate occupancy (i.e., at least one patch occupied) compared to combinations of SS patches, while controlling for total forest amount. We find that, in most cases, SS and SL patches of the same cumulative habitat amount have equal occupancy. In the remainder of cases, we find a tendency for primate occupancy to be higher in combinations of SS than SL patches. This result holds regardless of a species' threatened status. These findings suggest that, even for threatened primates, the traditional SL > SS principle does not hold. They highlight the high cumulative importance of small forest patches for primates, and the need to increase their consideration in conservation. • Several small forest patches and few large forest patches of the same total area have generally equal occupancy of primates. • Small forest patches have high conservation value for primates threatened with extinction. • Primate conservation requires protecting as much forest as possible, irrespective to patch size.