Climate change pushes monkeys and lemurs from tree canopy to forest floor, study finds


A statement in this article by Amanda Korstjens, professor of behavioral ecology at Bournemouth University in the UK, has been incorrectly attributed to Andrew Bernard, a PhD student in anthropology at the University of Michigan. It has been updated.

Stress from warming temperatures and forest loss is causing dozens of species of monkeys and lemurs that normally shelter and feed high in the tree canopy to spend more time foraging, according to a study released Monday. food on the forest floor.

The results demonstrate how human-caused climate change is forcing animals to adapt and disrupting the ecological web they inhabit.

More than 100 scientists who have spent some 151,000 hours observing animals in Madagascar and Central and South America have found that primates risk being exposed to new predators to escape the heat and find food, although that they still spend the vast majority of their time in the trees.

The species most likely to adapt to spending time on the ground – whether because they have more diverse diets, live in the relative safety of large groups, or are physiologically more able to roam the forest floor – are most likely to descend from trees, and therefore may be more likely to survive in the future, said Tim Eppley, postdoctoral associate at the San Diego Zoo Wildlife Alliance. Eppley is the lead author of the study, which was published in the Proceedings of the National Academy of Sciences.

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As global warming accelerates and deforestation and wildfires spread, the primates least advantaged for such a transition will be increasingly at risk.

“They won’t be able to live long,” Eppley said. This could aggravate ecological challenges in vulnerable forest habitats, as animals such as lemurs play an important role in tree seed dispersal. “Once you get rid of the lemurs, there’s this whole cascading effect.”

The scientists said the research showed hopeful signs for the resilience of vulnerable creatures and ecological systems, while underscoring the need to slow or prevent warming and habitat loss.

“Madagascar’s primates are already the most endangered in the world, but studies like this show us that they could find refuge from the worst climate change by adapting flexibly to spend more time in areas where temperatures are lower,” Amanda Korstjens, a professor of behavioral ecology at Bournemouth University in the UK, wrote in an email. “But the study also underscores the importance of preserving healthy forest habitats to allow primates to use the limited options they have to manage global warming.”

Helen Slater, a research associate at the University of Newcastle in the UK, said the study suggests “quite a daunting task” to predict how various primate species will respond to climate change and to determine how best to promote their conservation .

Madagascar’s lemurs face a bleak future because of human activity. A solution? To plant trees.

“There won’t be a one-size-fits-all solution, and we will likely need to develop site- and species-specific strategies,” she said in an email.

The research began with Eppley’s own observations. He spent a year observing southern bamboo lemurs in southeastern Madagascar and collecting data on their nutrition. He was surprised to find that in degraded forest habitats, animals were willing to risk their lives to descend to the forest floor, where they gathered more nutritious food and sometimes even slept. In a healthy, continuous rainforest, lemurs would “almost always” be found in trees or stands of bamboo, Eppley said.

Then, a discussion at a conference in 2016 about his observations and questions, which other researchers shared, became the genesis of the study. Eppley began contacting anyone he could find who had spent time tracking primates, and eventually contacted 118 co-authors at 124 different institutions. The study is entirely based on raw observations of monkeys and lemurs, as opposed to analysis of a sample, taken from 1985.

The study came to various conclusions about what makes primates more likely to leave their natural habitat in trees. Those who live in large groups can descend to the ground more often because the number is safe, as can those who are willing and able to eat more than just fruit. The warmer the climate and the sparser the forest cover at a given site, the more animals are likely to descend to the ground.

But in areas close to roads and other human infrastructure, primates were less likely to spend time on the forest floor, perhaps because that often means proximity to wild dogs, the study found.

According to Amanda Korstjens, professor of behavioral ecology at Bournemouth University in the UK.

The researchers said further investigation was needed to analyze in detail what is driving the changes in primate habits. For example, comparing ground and canopy temperatures at observing sites could better demonstrate the role warming temperatures play, Slater said.

It is unclear how significant the variation in the ability of primates to adapt to a ground habitat will be over the long term. The study found that of the 15 species of lemurs and 32 species of monkeys observed, they spent less than 5% of their time on the ground, on average, a level low enough for Korstjens to wonder how much this habit may be important to a primate’s survival.

And it’s not safe to assume that some species will thrive simply because they might be more adaptable to spending time in the field, said Andrew Bernard, a doctoral student in anthropology at the University of Michigan whose research focuses on primate behavior.

“Many primates spend considerable time in poor quality habitats that could not independently maintain viable populations,” he said.

But the study still emphasizes the effects of global warming on animals, and the adaptations it requires of them.

The study focused on primates in Madagascar and the Americas, as similar species in Africa and Asia already underwent similar transitions millions of years ago from living primarily in trees to life on the ground. It’s a relatively common evolutionary transition in primates, even though what the researchers observed looks different.

“What we’re seeing now is largely man-made,” Eppley said. “It’s happening so fast.”

Teresa H. Sadler