Forewords

Lisa and Kari’s partnership expanded due to another—increasingly urgent—conservation issue. Census reports showed a precipitous decline in the subspecies of mantled howler monkeys at Hacienda La Pacifica, a 3,000-acre privately owned ranch in the Guanacaste province of northwestern Costa Rica. The species was generally protected from hunting and habitat loss, so the question was, What was driving this decline?   

“We just started talking about health. Were these primates healthy?” Lisa remembers the growing concerns of her and her research team. “That’s when Kari's expertise really started to come in.”   

Kari brought new questions—Do you know their microbiomes? Do you know their healthy blood parameters?—when she traveled to Costa Rica for the first time in summer 2019. “I’m usually in the lab. I study gene expression and protein expression, and I look at how bacteria interact with their microenvironments. And this collaboration challenged me to look at the bigger picture,” says Kari.   

As collaborators at La Pacifica, Lisa and Kari worked closely with local partners, including veterinarians, researchers, and animal rescue centers, as well as other colleagues from all over the world.  

On a typical day, the team usually wakes up around 4 a.m. to locate the monkeys. They listen for their characteristic howling—as howler monkeys boast the loudest call in the terrestrial animal kingdom.

“Everything is dark, but the forest is beautiful and musical and magically buzzing with activity.  The howler calls fill me with joy every time I hear them,” says Kari.    

“It's hard not to be changed at least somewhat when you have the extremely rare privilege of sitting under a tree, in a different country, watching wild monkeys,” agrees Lisa. “They just feed my soul.”  

If Lisa, Kari, and their students (in the field and in the lab) can better understand what’s going on with this otherwise relatively well-protected population of howler monkeys, they can take more direct actions. For instance, they could work with the government to protect corridors and plant appropriate tree species, among many other significant measures—as well as extrapolate their findings for other species of primates. 

“If we have somehow implemented something that helps to conserve this population, that is part of the broader aspects of sustainability—of preserving our world—that is highly important to me,” says Lisa.