A team of researchers, led by University of Colorado Boulder primatologist Michelle Sauther, found that the consequences of climate change are disproportionately affecting smaller primates from two different species of the bush baby family.

The team’s research took them on 75 night-walks through the Lajuma Research Centre in South Africa’s Soutpansberg Mountains from July 2017 to June 2018. On these trips, the team — which also included researchers from the University of Pretoria and University of Venda in South Africa and the University of Burgundy in France — searched for two different kinds of primates: the southern lesser galago and the thick-tailed greater galago, also known as bush babies.

These primates are remarkably similar on paper: Both are classified as small mammals, nocturnal, and live nearly their entire lives in the trees. Both hunt for insects at night and lick up gum from acacia trees. One of the only ways they differ is their body size: Greater galagos are the size of large cats, while lesser galagos are as small as squirrels and weigh less than a soda can.

“It’s kind of like if you were comparing a gorilla and a monkey,” said Sauther, a professor in the Department of Anthropology at CU Boulder. “We’re talking about those kinds of differences.”how an animal adapts to extreme temperatures?

During their walks, the team found that the lesser galagos were out and about in the forest much more often than the greater galagos, braving temperature extremes in a forest where annual temperatures can swing from near freezing in the winter to 100 degrees Fahrenheit in the summer.

The lesser galagos were also out later into the night, and were found in all weather conditions.

The greater galagos, on the other hand, tended to wait out harsh weather conditions and temperatures, and were more active earlier in the night.

This relaxed attitude is can be explained by the greater galagos’ larger body size and slower metabolism, according to the study.

A smaller body mass requires more consistent energy, meaning that the lesser galagos needed to forage no matter the time of night, temperature, or weather to gather enough food to get them through the following day. The greater galago’s larger body mass may act as a buffer between active periods that allows them to be more selective about when they forage, according to the study.

“What we found is that during really cold temperatures or really hot temperatures, the smaller species just kept going … They can’t sit back like the bigger species and choose and say, ‘Well, I’m going to get out there, but it’s going to be during this period of time,’” said Sauther.

The lesser galagos’ small size and need to forage even in more extreme conditions exposes them disproportionally to the effects of climate change, according to the study.

“When you think about small primates or just small mammals, we tend to think small mammals are all the same, but they’re not. There’s a huge variance in terms of body mass,” said Sauther. “So if you’re really small, versus very large, you’re going to be affected by climate change in a very different way.”

These findings come as a result of a deliberate choice to focus on under-studied primates. Because these species are both nocturnal, it requires a whole lot more effort for humans to seek them out and track their habits. The researchers used thermal imaging and documented the frequency of their encounters with each species.

“If you ever go out and walk around at night, it seems alien. There’s reasons that people are afraid of the dark,” said Sauther. “So if you’re gonna study these guys, the orientation at night is difficult because again, we’re so tied to activity during the day.”

Sauther said studying overlooked primates like these galagos is important because discovering vulnerabilities is an important part of conservation efforts.

“I’ve always studied underdog primates. I don’t study chimpanzees and gorillas, I study these,” said Sauther. “It was really important to study these nocturnal primates because they are so under-studied, and how are we going to know their conservation status if we don’t get out there and actually study them, see where they are?”

Now that the team’s data is out there, the next steps are to partner with local researchers and see what can be done to help conserve these species, given the new knowledge about their relationships with climate change.

“We’re really interested in working with, and have started to develop associations with, South African universities. And the main reason is to pass on (our knowledge) and collaborate with local researchers and also to help facilitate teaching the next generation of scientists in South Africa,” said Sauther. “We’re hoping to also have an interchange of intellectuality in terms of having our students and their students work together on a lot of these projects to develop this more global approach.”

Read the study at link.springer.com/article/10.1007/s10764-024-00427-5