LAUSR

Non-human primates are among the most threatened mammals on Earth. Although some species, such as howler monkeys, are thought to be resistant to initial phases of habitat disturbance, the lack of longitudinal studies prevents determining if this holds over time. We assessed temporal changes in landscape structure in the Lacandona rainforest, Mexico, and how these changes relate to population trends of black howler monkeys (Alouatta pigra). We surveyed primates in 22 forest sites in 2011 and 2017, and related temporal changes in primate abundance and immature-to-female ratio with changes in the spatial structure of local landscapes (forest cover, matrix openness, number of forest patches, and forest edge density) using a multi-scale approach. Landscape changes occurring over a 6-year period were strongly associated with temporal changes in population parameters. Primate abundance increased as forest cover increased. Both primate abundance and immature-to-female ratio increased in sites located in landscapes where the number of patches increased over time, but where the proportion of open matrix decreased. Edge density showed a negative effect on immature-to-female ratio. This endangered primate might not be as tolerant to landscape disturbance as generally thought. Allowing forest patches to increase in number and/or size through active or passive restoration (reverse fragmentation), and preventing forest loss and an increase in matrix openness are key management strategies to preserve howler monkeys in this biodiversity hotspot.