Ecologically speaking, humans maintain a pretty broad niche. We can adapt to live just about anywhere. Most other species aren't that lucky. Take the four species of lion tamarins, for example. These small, endangered monkeys of the genus Leontopithecus rely on very narrow niches of habitat in the Brazilian Atlantic Forest, areas that already face tremendous pressure from agriculture and development. Many tamarin populations are currently stuck in small pockets of forest, surrounded by developed land with no way to spread out and connect with other members of their species.

That situation is only going to get worse as climate change shrinks or otherwise alters most of those areas. According to a paper published this past December in the American Journal of Primatology, all four lion tamarin species will lose important parts of their habitat in the coming decades (the researchers used climate models to determine habitat suitability in 2050 and 2080). Even the protected areas in which many of the monkeys currently live may not be enough in the long term, the paper warns.

Climate change will have a particularly dramatic effect for these four species because they have small, fragmented populations and limited ability to disperse to new territories, according to Andreas L.S. Meyer, the lead author of the study and a Ph.D. student at Universidade Federal do Paraná (Federal University of Paraná) in Brazil.

Each of the four lion tamarin species will be affected to differing degrees, as will the areas set aside for their conservation. Golden-headed lion tamarins (L. chrysomelas), Meyer and his colleagues found, will lose about 87 percent of their current suitable habitat by 2080. Black lion tamarins (L. chrysopygus) will find their territory restricted by 28 percent, leaving them with just a single viable population. Golden lion tamarins (L. rosalia) will be set back the worst, with only a few patches of their landscape remaining suitable by 2080.

Interestingly, the researchers found that the black-faced lion tamarin (L. caissara)—the only one of the four species that is critically endangered—will face the least danger from climate change, although it should probably be considered at the most risk overall. The species only numbers about 400 animals and occurs in just a handful of isolated locations.

Of course, climate change is only part of the story. Going back to the golden-headed lion tamarins, the part of their habitat that will be least affected by climate change faces other threats. Cocoa plantations dominate that region, as does the "cabruca" system of shade-grown agriculture. "The conservation of the cabruca becomes a very important tool to protect the species," Meyer says. "Unfortunately, the economic viability of the production of cocoa is presently threatened by poor management practices, diseases and cattle grazing, which jeopardize the future persistence of golden-headed lion tamarins in the region." He says protecting the cabruca system should be considered a conservation priority for the species.

Meanwhile, deforestation continues throughout Brazil, which means the 13 current protected parks and refuges set aside for lion tamarins—all of which will shrink due to climate change—probably won't be enough to protect the four species. "The Brazilian government has recently approved a new and controversial forest law which reduced the area that landowners would have to preserve, gave amnesty from fines for illegal deforestation and reduced the limits of areas of permanent protection," Meyer says. "Therefore, I believe current conservation efforts are delaying, but not avoiding, a future decline of lion tamarins' populations." He adds that the conservation of the genus will heavily rely on private land in the coming years.

Unfortunately, conserving land and the monkeys may not be easy. "Farmers and construction companies are such a powerful lobbying group [in Brazil] and most people really do not care about the environment," Meyer says. He hopes that other researchers will take up the call to study tamarin genetics and assess their wild populations, but he says that will be both difficult and expensive. "This will only be possible with significant investments in long-term conservation programs. In our current pace, I think such a goal will be hardly achieved."

Photo: Golden lion tamarin by Brian Wright via Flickr. Used under Creative Commons license