A Red Flag for Red Colobus

Hunted by humans and chimps and besieged by civil war and deforestation, Africa’s red colobus monkeys have few reasons to celebrate.

Glen Darrud/Flickr

The Year of the Monkey swings in today! For the past several weeks, in honor of the Chinese New Year, this series has covered lots of monkey business currently happening across the planet. Now, as fireworks blast over Beijing and elsewhere, Jason Bittel checks in on the red colobus.

In the run-up to the Year of the Monkey, we’ve looked at squirrel monkeys captured and sold as pets, macaques forced out of the forest, drills hunted to near oblivion, and snub-nosed monkeys surviving thanks only to panda conservation. The fact is, the monkey branch of our family tree is looking pretty tattered, but perhaps no single genus is in more trouble than the red colobus.

These wiry, medium-size monkeys with beautiful black, white, and burnt-orange fur (if you squint, they look a little like calico-coated gremlins) live across sub-Saharan Africa, where they must contend with their number one enemy, humans, the close relatives of their number two enemy, chimpanzees.

There are 18 subspecies of red colobus, but according to the International Union for the Conservation of Nature, only one seems to be doing OK (the Oustalet’s red colobus). Of the remaining 17 subspecies, 6 are listed as critically endangered, 3 as endangered, and 2 as vulnerable. Too little information exists to establish a proper rating for the other 6, but they’re most likely in dire shape, too. Take Procolobus badius bouvieri, which hasn’t been spotted in its native Congo for more than 20 years and is in all likelihood extinct.

To understand why red colobus monkeys are faring so poorly, I talked to Thomas Struhsaker, an evolutionary biologist at Duke University who wrote the book on red colobus monkeys. In Struhsaker’s mind, human population growth is the monkey’s primary problem. According to the World Resources Institute, between 1980 and 2000, the U.S. population grew 0.7 percent, Asia’s grew by 1.6 percent, and South America’s by 1.8 percent. But in sub-Saharan Africa, the only place in the world with wild red colobus monkeys, the growth rate was 2.7 percent. A more recent study, from 2013, anticipates that Africa’s population will more than double by 2050, from roughly 1.1 billion to 2.4 billion people—and most of that growth will be seen in sub-Saharan Africa.

More people require more food, space, and infrastructure, the demands for which put monkeys at risk as forests are cleared for agriculture, trees are converted into timber and charcoal, and wild animals are hunted for subsistence and income. Indeed, according to Struhsaker, the latter may be the most direct threat to the red colobus, as the monkeys are “unusually susceptible” to hunters.

This vulnerability may partly lie in their taste for leaves, a food source that’s both abundant and, once you’ve climbed the right tree, easy to collect and consume somewhat mindlessly. But what seems to be a pleasant, easygoing lifestyle could actually put these animals at a survival disadvantage. Struhsaker says monkeys that feed on fruit and insects seem to do much more visual scanning, perhaps because their foods are more dispersed, so they’re always looking to the next branch.

“Scanning detects not only food, but potential predators,” says Struhsaker.

Photo: Graham Laurence/FlickrA red colobus monkey in Zanzibar's Jozani Chwaka Bay National Park

A glance across the subspecies quickly reveals hunting’s devastating impact. In Sierra Leone, Guinea, Liberia, and Cote d’Ivoire, unsustainable hunting is the biggest threat to the red colobus taxon known as badius. Between 1986 and 2006, on Bioko Island in Equatorial Guinea (home to the drills I wrote about previously), 45 percent of the subspecies pennantii was killed and consumed as bushmeat. Since the 1960s, the Democratic Republic of Congo has been mired in civil war, which has led to the proliferation of assault weapons that enable hunters to kill 50 to 100 of the tholloni subspecies per day. And in Cote d’Ivoire and Ghana, the only evidence of the continued existence of the red colobus known as waldroni—which hasn’t been seen in more than 25 years, thanks in part to poaching—was, ironically, a single pelt brought in by a hunter.

Making matters worse, humans aren’t even the only ape targeting the monkey. Chimpanzees—once thought to be peaceful herbivores—are also carnivores with a particular affinity for red colobus meat. According to one study, chimps in Tanzania’s Gombe National Park kill and eat up to 40 percent of the area’s red colobus population annually. Other studies, one of which was authored by Struhsaker, found that chimps in Uganda’s Kibale National Park have reduced its local red colobus population by as much as 80 percent.

In an ecosystem undisturbed by humans, red colobuses would be able to weather the predation by chimps. But considering the sad state of the red colobus already, the threat of marauding chimpanzees is certainly salt on the wound.

Even in areas where predation (human, chimp, or other) doesn’t take much of a toll, agriculture and human development have carved up and degraded many of the forests the red colobus calls home. This is true of Senegal, Gambia, and Guinea Bissau, where the subspecies temminckii once thrived but is now down to just 2,000 individuals. The Kenyan subgroup rufomitratus has seen its trees uprooted for large-scale rice plantations and its rivers tamed by hydroelectric dams. With fewer than 1,000 monkeys remaining, rufomitratus is considered the least numerous and most endangered of all African primates.

In Zanzibar, the subspecies kirkii is critically endangered, due in part to a tourism boom. Habitat has been reduced as more tourists have increased the need for firewood, charcoal, and timber—and for roads, which often lead to monkey roadkill.

No matter the country or cause of colobus catastrophe, the common denominator is us. When people show up, red colobus monkeys get gone. And humans aren’t going anywhere anytime soon. When asked if he thinks red colobuses will be around by 2050, Struhsaker replies, “I am not optimistic.” Even if we were able to curb our growth and better manage the animals’ remaining habitat, Struhsaker worries that human population inertia may be too much for this species on the brink.

But what if with every new year there really were new possibilities? And what if we could ring in the next Year of the Monkey, 2028, with better news for the red colobus? Some things would definitely have to change—and quick. If only we humans could evolve our land-use practices, hunting habits, and how we wage war. C’mon people, let’s show those chimps how it’s done. 

onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.

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