Researching Howler Monkeys In Costa Rica: One CNM Instructor’s Quest to Help This Threatened Population

For about a month this summer, Susan Ruth, an Anthropology instructor at CNM would wake up at 4 a.m., get dressed, and walk out into the pitch-dark La Suerte jungle in Costa Rica. She was up at this crazy hour because she had to be in place by 4:30 a.m., which is when the famous howler monkeys start their deafening morning chorus of howls. 

Once she heard a group of monkeys she would get as close as possible and start looking at her watch. She would time the length of those morning howls and then time the length of their other howls throughout the day. She knew the monkeys had different howls for different things— the morning howls, howls for predators, howls for other monkeys, and even a howl for rain—and wanted to know how long each one lasted. 

“You have to be there to truly experience the howls,” she says. “They’re amazingly low-pitched. And even though the monkeys are not very big, they have a really oversized voice.”

Susan says it was intimidating to be out in the jungle by herself in the dark listening to a cacophony of sounds. But she got used to it and was amazed at all the wildlife she saw in addition to the howler monkeys. 

“It was definitely a little scary, but it also quickly started to feel like home. And I got to see so many animals including spider and capuchin monkeys, as well as snakes, poison dart frogs, and sloths.”

The program was conducted through the Maderas Rainforest Conservancy in Costa Rica and Susan used her CNM Distinguished Faculty Award funding to pay for the trip. She’s already thinking about a return and wants to bring CNM students with her so they can experience the jungle and conduct their own research. Before COVID, Maderas offered student scholarships and she’s hoping those will soon return.

Susan’s findings will be presented at the American Society for Primatology conference next year. And while the research was empirical to start, it has much broader applications with regard to conservation.

She says the La Suerte jungle shrunk dramatically because of the expansion of monocrops like palm and pineapple. As a result, the howler monkeys have a significantly smaller habitat and increasing population density. Her research and the research of others will contribute to a larger project that monitors the monkey’s overall community health as they continue to be squeezed.

“It was a thrill to study monkeys in the wild and to be a part of the conservation effort at La Suerte so that future generations can study and enjoy the rainforest,” Susan says.