Some primates spend their entire lives in trees. They avoid the ground, where preferred food is scarce and predators lurk. But deforestation and climate change are threatening their homes in the branches. Habitat loss has some primates swinging down to see what the ground offers, scientists reported recently in the Proceedings of the National Academy of Sciences.
The massive study included more than 150,000 hours of observations from 20 sites in Madagascar and 48 sites in the Americas. A global team of 118 researchers analyzed 34 years of field observations of tree-dwelling monkey and lemur species.
On average, primates in the study spent less than 5 percent of their time on the ground. It doesn’t sound like much, but any time on the ground is dangerous. Predators can strike in a matter of seconds, said study co-author Patricia Wright, a conservation biologist at Stony Brook University in New York. Even so, some animals take the risk.
The study revealed that species with certain social and physical traits may have an advantage. Primates with diverse diets and larger group sizes might adapt more easily to terrestrial life. So might animals with smaller body masses — an unexpected finding. Scientists are still working to understand why this is the case.
These findings offer a bright side to a difficult problem, said primate expert John Fleagle of Stony Brook University, who was not part of the team: “Even though habitats are disappearing, some [primates] can figure out how to deal with this new habitat that they’re suddenly finding below them.”
One disappointing finding was that primates stayed tree-bound near buildings and roads. Our infrastructure could inhibit primates from descending to ground, restricting their movements between patches of healthy forest and interfering with their ability to adapt, Eppley noted.
And some species may never adapt. Conservationists have discussed strategies to help them, such as building rope bridges to connect habitats. “It’s going to require us to become innovative and creative and thoughtful about how the animals think,” said Wright. “Not how we think, but how the animals think.”
