Essay: Lemurs in Madagascar—Now
The ring-tailed lemurs that romp around the research camp at the Beza Mahafaly Special Reserve in southwest Madagascar spend plenty of time behaving badly. They slide down tents, peer at their reflections in pickup truck windshields, and rummage through trash cans. It's their playful and versatile nature, in part: as "generalist" species, ring-tails can adapt to a range of habitats. But this population also resides in a conservation area with abundant resources and few threats. "The lemur group at the camp has a lot of luxury in terms of time," says Michelle Sauther, an anthropologist from the University of Colorado at Boulder who spends three months of the year at Beza Mahafaly. "If they don't have to run around looking for food all the time, even ring-tailed lemurs can sit back and relax."
Local villagers offered to set aside 600 hectares of the Beza Mahafaly forest to form the reserve in the late 1970's. Remote and nearly the smallest protected area of the 46 on the island, it is hardly as popular with eco-tourists as the rain forests of Ranomafana and Perinet. But the range of Malagasy habitats it contains is remarkable. These include a lush "gallery" forest that lines the seasonal Sakamena River and a dusty "spiny desert" forest with towering cactuslike trees. Beza's habitats support five of the dozens of lemur species on Madagascar, most notably the housecat-sized, raccoon-faced ring-tails and the paler, silkier Verreaux's sifaka.
Sauther has monitored lemurs at Beza Mahafaly for about twenty years. With conservation as its goal, her work aims to understand how changes to Madagascar's environment—mostly brought about by human beings—affect the behavior, health, and evolution of lemurs. In the land outside the reserves, these changes have not afforded lemurs much time to goof off.
Madagascar was one of the last landmasses settled by humans. It is likely that maritime traders sailing the Indian Ocean first stepped on its southwest coast some 2,300 years ago. The earliest indirect evidence of the "human footprint" is the slashed bones of extinct lemurs found at Taolambiby, a dusty creek bed seven kilometers or so from Beza Mahafaly. Hundreds of hacked bones of Verreaux's sifaka were also dug up at Taolambiby. The cut marks, probably exacted by iron butchering tools, are an eerie testament to some of humans' first impacts on lemurs.
The locals near Beza Mahafaly no longer eat sifakas (it's taboo), but lemurs are still hunted elsewhere in rural Madagascar. More deleterious than hunting pressure, however, has been the swift, dramatic effects of agriculture. Much of Madagascar's original forest has been converted to cropland, pastureland, or eroded wasteland via axe, machete, and fire. (Besides reducing habitat for arboreal species like lemurs, slash-and-burn deforestation exacerbates soil erosion, which occurs at a higher rate in parts of Madagascar than anywhere else in the world.) These days, deforestation occurs at a rate of just under 1 percent a year. Although there are only 32 humans per square kilometer on Madagascar, the island's population is poised to double by the year 2025. At least 16 species of lemurs have disappeared since humans arrived, and all lemurs living today are threatened with extinction to some degree.
Generalists vs. Specialists
Lemur research in the protected areas helps inform conservation. At Beza Mahafaly, ring-tailed lemurs and sifakas are observed, counted, captured, DNA-sampled, checked for parasites, collared with radio-tracking tags, then released; they even have casts made of their teeth. Both populations at the reserve appear stable. "Ring-tailed lemurs are widespread in the south of the island, but that's not to say they're not threatened," says Sauther. "But they seem to be able to deal biologically with habitat change." The generalist ring-tails can cope with, and even take advantage of, some anthropogenic change. For one, they'll eat anything: flowers, insects, fruit, but also less-nutritious tourist handouts, crops, and food refuse. "They're able to exploit a wider resource base than the sifakas, who have a more narrow folivorous, or leaf-eating, diet," explains Sauther.
Ring-tails are also more terrestrial than the arboreal, "specialist" sifakas. "Ring-tailed lemurs are able to utilize all parts of the forest," says Sauther, "from the very tops of the trees to the ground itself." Biologically, sifakas can't afford the energy costs of frequent travel across a denuded habitat, so they leap on trees instead. But when the trees disappear, sifakas are stuck. "Many of the fossil lemurs, the extinct species, were hyperspecialized," says Sauther. "They simply could not adjust to the loss of habitat."
Many regions around Beza Mahafaly are largely treeless, instead dotted with cassava, maize, and sweet potatoes and with grazing zebu cattle and goats. Scientific comparisons of lemurs inside and outside the park show that the reserve animals generally travel less far to forage and are healthier. The rich resources of the reserve do appear to be a magnet for ring-tailed lemurs: the population density within the reserve is much greater than in the surrounding habitats. But higher animal densities in these isolated reserves bring new population pressures.
Many Populations, Same Island
"One of the things that I've noticed over the almost 20 years that I've worked here is that reserves really do work," says Sauther. "But they only work when you have the local people involved." Beza Mahafaly was among the first Madagascar conservation projects to involve local residents, a few thousand of whom live in straw-roofed huts outside the reserve. The villagers agreed to protect the lemur habitat, and governmental and nongovernmental organizations agreed to improve the residents' water access, roads, schools, and other infrastructure. "The villagers are participating in the long-term research that we've been undertaking at Beza Mahafaly," says Joelisoa Ratsirarson. He's Madagascar's general secretary of the minister of the environment, water and forestry and also a biologist who studies the park's sifakas. "We train the villagers to monitor the survivorship and movement of the lemurs. The local population is very helpful in protecting the reserve and really respects the lemurs."
Ratsirarson says that although the Malagasy government "lacks the means for conservation activities," habitat protection is a political priority. It is mostly accomplished in cooperation with international groups like the World Wildlife Fund and Conservation International. Marc Ravalomanana, Madagascar's president, has vowed to extend its protected area to 10 percent of the country by 2008. Right now, it's about 3 percent. "So it's really a challenge," says Ratsirarson.
Sauther admits, "I used to feel depressed when I came here, because you see the habitat changing and a lot of fragmentation occurring." She says that the government may expand Beza Mahafaly to include surrounding fragmented areas and the people that live in them. "The locals would still use the resources here, but in ways that support both the humans and the lemurs themselves," she says. "So I'm feeling a lot more hopeful than I used to."
Beza Mahafaly Lemur Biology Project
Michelle Sauther's research project website.
Conservation International Biodiversity Hotspots: Madagascar and the Indian Ocean Islands
NOVA: Legends of Madagascar
An essay on Malagasy beliefs and legends, including those about the island's animals.
More About This Resource...
Our innovative Science Bulletins are an online and exhibition program that offers the public a window into the excitement of scientific discovery. This essay was published in April 2006 as part of the Lemurs of Madagascar: Surviving on an Island of Change Bio Feature.
- It begins with a look at the ring-tailed lemurs at the Beza Mahafaly Special Reserve in southwest Madagascar, who have plenty of time to behave badly.
- It then details how life has changed for lemurs in the wild since humans first came to Madagascar 2,300 years ago.
- The essay includes a look at the differences between generalists and specialists.
Supplement a study of biology with a classroom activity drawn from this Science Bulletin essay.
- Have students read the essay (either online or a printed copy).
- Have students write a brief reaction to the essay, explaining in their own words the difference between generalists and specialists and how being the former has helped the ring-tailed lemur adapt to environmental changes brought by humans.