Deforestation and climate change are driving tree-dwelling primates to descend to more ground living

A large-scale research study of 47 species of lemurs from Madagascar and monkeys from the Americas has found that tree-dwelling species are being driven to the ground due to the impacts of deforestation and climate change.

Spending more time at ground level helps primates cope with the rising temperatures, which is caused by a combination of climate change and loss of vegetation cover in the forest environment.

Dr Giuseppe Donati, Reader in Primatology and Biological Anthropology at Oxford Brookes University, was one of the two senior authors of the research. Dr Marco Campera, lecturer in Conservation and Biodiversity, and Dr Michela Balestri, associate lecturer for the School of Social Sciences, both also of Oxford Brookes University, also contributed to the study.

They were part of a team of expert researchers who examined more than 150,000 hours of observation data on 15 species of lemurs and 32 species of monkeys at 68 sites in Madagascar and the Americas. The study included 118 co-authors from 124 different institutions.

Disturbed environments driving primates to ground

The study began after the researchers noticed that certain populations of primates were spending more time on the ground than expected. However, at sites with less deforestation, members of the same species did not descend to the ground.

Dr Donati said: “The study showed that monkeys and lemurs that live in hotter environments with less canopy cover were shifting toward more extensive ground use. Furthermore, tree-dwelling species which consume a more generalised diet and live in large social groups were more likely to make these changes.”

Many primate species are already forced to live with changes caused by humans to their habitat. These include living in warmer temperatures, living in areas with less tree cover and therefore less shelter and food, and living in closer proximity to humans and domestic animals.

There are over 600 species of primates, but more than 50% of them are now threatened by habitat loss and fragmentation, which represent the main threat to their survival.

As climate change worsens and forests recede due to human activities, the study suggests that more flexible species are shifting to a new ecological dimension that can buffer them against extinction.

The lead author of the paper, Dr Tim Eppley, a postdoctoral associate at San Diego Wildlife Alliance (SDZWA) and former MSc student in Primate Conservation at Oxford Brookes University, said: “It’s possible that spending more time on the ground may cushion some primates from the effects of forest degradation and climate change; however, for the less-adaptable species, fast and effective conservation strategies will be necessary to ensure their survival.”

Human influence on primate adaptation

The study also found that primates closer to human settlements and roads are less likely to descend to the ground. In addition to forest exploitation, various aspects of human encroachment may play a role in this ecological transition, including feral dogs which are known to prey upon wildlife.

Dr Luca Santini, from Sapienza University of Rome, another senior author of the study, said: “This finding may suggest that human presence, which is often a threat to primates, may interfere with the natural adaptability of the species to global change.”

Dr Donati added: “Though analogous ecological conditions and species traits may have influenced previous evolutionary shifts to ground living, including our hominin ancestors, it is very clear that the current pace of deforestation and climate change puts most primate species in peril.”

Nadine Lamberski, Chief Conservation and Wildlife Health Officer at San Diego Wildlife Alliance, who was not involved in the study, remarked on the impressive scale of this collaborative scientific initiative.

Nadine said: “This is an extraordinary effort to convene 118 authors and review data of this magnitude. It is also a tremendous example of the insights that can be gleaned and strides that can be made when conservation is examined on a global scale.”

The research is published in Proceedings of National Academy of Sciences (PNAS) and is titled ‘Factors influencing terrestriality in primates of the Americas and Madagascar’.