Rare Lemur Spots Danger By Listening To Other Species’ Alarms

394px-Lepilemur_sahamalazensis_bYou’ve probably never heard of the Sahamalaza sportive lemur (Lepilemur sahamalazensis). The Madagascan species was only discovered in 2006, living in a tiny area on the northwest coast of the island off Africa. Though the lemur’s home recently received protection, the animals are threatened by agriculture and charcoal production. And their rareness prompted the IUCN to move the sportive lemur into the Critically Endangered category just this month.

Unlike some other more familiar lemur species, like the ring-tailed lemurs often seen in zoos, Sahamalaza sportive lemurs are solitary critters that are active at night. During the day, they rest outside tree holes or among tree tangles. It lets them soak up the sun, but staying out in the open also makes them vulnerable to predators, such as the Madagascar harrier hawk, a cat-like carnivore called a fossa, and — perhaps — the Madagascar tree boa. Plus, there are human poachers to worry about.

How do the lemurs manage to keep an eye out for all these threats? They listen to other species that are on the lookout for them, say researchers led by the Bristol Conservation and Science Foundation in the UK. They report their findings in PLOS One.

The scientists traveled to the Ankarafa Forest in the UNESCO Biosphere Reserve and National Park on the Sahamalaza Peninsula in Madagascar to study the lemurs in their home territory. The researchers found 19 Sahamalaza sportive lemurs and, between September and November 2011, played the primates recordings of the vocalizations of other species and watched how the lemurs reacted. Those calls were from two birds, the Madagascar magpie-robin and the crested coua, and another lemur, the blue-eyed black lemur. The researchers played alarm calls that warn of predators as well as sounds the birds and lemurs make when coming into contact with each other, called contact calls.

When the sportive lemurs heard the playbacks of alarm calls that warn of an aerial threat, they became more vigilant and began looking up into the sky. But when they heard terrestrial alarm calls or contact calls, the lemurs didn’t react. (The researchers aren’t sure if the Sahamalaza sportive lemur’s non-reaction to the terrestrial alarm calls mean that they don’t recognize them as a sign of danger or that they decided that it’s just not worth their time.)

“Our results indicate that the Sahamalaza sportive lemur is capable of gleaning information on predator presence and predator type from the referential signals of different surrounding species,” lead author Melanie Seiler, of the Bristol Zoo and the University of Bristol, said in a statement. “Examples for cross-species semantics in lemurs are rare, and this is the first record of lemurs using information across vertebrate classes.”

This ability to listen in on other species is especially important for a solitary creature like the Sahamalaza sportive lemur, the scientists say, because these animals can’t rely on a group of buddies like the ring-tailed lemur can. If they want to avoid predators, eavesdropping can give this sportive lemur a heads up on some of the dangers they face.

Image courtesy of R. Hilgartner, via wikimedia commons

You Might Find A Hibernating Lemur Underground

lemur1When I think about hibernation, I picture a squirrel nestled in a tree or a bear in a cave, waiting out the winter. Primates don’t hibernate, and there would especially be no reason for tropical ones to do so, right? But in 2004, scientists discovered a lemur in western Madagascar that did, breaking the no-primate and cold-winter-only rules. The fat-tailed dwarf lemur uses hibernation — the state in which metabolic rates are lower, the animal’s core body temperature matches that of its environment, and certain physiological functions cease — to survive the dry season. The animals hide out in tree holes while temperatures are hot, water dries up, and food disappears, emerging months later when conditions are more friendly.

Now a group of scientists, from the United States, Germany, and Madagascar, report that they have found two more species of lemurs — Sibree’s dwarf lemur and Crossley’s dwarf lemur — that also hibernate. Their study appears in Scientific Reports.

These two species of dwarf lemurs live on the east side of Madagascar, in high-altitude rainforest. This area of the country also experiences wet and dry seasons, but the temperature variations here are greater. It never gets warmer than 85 degrees Fahrenheit and it sometimes reaches temperatures below freezing, making this one of the coldest places in Madagascar.

During the cold winters, the researchers found, the two eastern dwarf lemur species dig burrows into the moist, soft soil and wait out the cold. “Underground shelters provide effective insulation during cold winters, when the ground is frozen or covered by a thick layer of snow,” the researchers write. “In Madagascar’s eastern forests, burrows provide more insulation — i.e., more stable hibernaculum temperature than tree holes or nests.”

That stable environment helps the lemurs keep a more stable body temperature throughout the winter, when ambient air temperatures can fluctuate wildly. The hidey holes might also keep them safer from predators, the researchers hypothesize, particularly if the lemurs are most likely to get eaten when exiting or entering their places of rest.

Unlike the fat-tailed dwarf lemur, these eastern species have a hibernation that looks more familiar, like that of a squirrel or chipmunk. It’s not so surprising, though. The researchers even admit this in their paper. But it can be hard to give up the assumptions we make, especially about things we learn when we’re kids. (And by the way, bear hibernation isn’t as straightforward as you were taught either.)

Image of Non-hibernating Crossley’s dwarf lemur from Tsinjoarivo forest courtesy of K. Dausmann