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Trailing Snakes in Madagascar

by AMNH on

From the Field posts

Madagascar’s rainy season is relentless. Unpaved roads turn to mud. Rivers flood. Feet start to blister from constant dampness. Humidity permeates everything, soaking maps, seeping into GPS units, attacking cameras and other electronic equipment. So why did herpetologists Christopher Raxworthy and Sara Ruane schedule their latest expedition to the island for January and February, at the height of the wet season?

Raxworthy Expedition in Madagascar
Christopher Raxworthy, Sara Ruane and the expedition team in Madagascar. 

“When I first came to Madagascar in 1985, there was very little practical knowledge about reptiles and amphibians anywhere, and most people were coming out in October or September,” says Raxworthy, who is associate curator in the Division of Vertebrate Zoology. “I remember talking to one of the really good local guides, and I asked him—when do you think is the best time to come out and look for chameleons, frogs, and snakes? He said, the middle of the rainy season. Since then, I’ve gone to Madagascar during the peak rainy season, and that’s made all the difference.” 

Raxworthy and Ruane Plotting the Trip
Herpetologist Christopher Raxworthy and Sara Ruane studying a map of Madagascar's Anakarana National Park. 
©AMNH/M. Lehmann

On this particular trip, Raxworthy and Ruane, a postdoctoral researcher, were carrying out a National Science Foundation funded study of Madagascar’s snakes, an unusually varied group given their relatively recent arrival on the island, about 30 million years ago. Each of the island’s snakes is an endemic species, found nowhere else in the world. That, plus the fact that Madagascar is relatively small, geographically isolated, and has habitats ranging from humid forest to desert to mountainous areas, makes the island “the perfect place to study speciation,” or the evolutionary processes that lead to new species, says Raxworthy. To document the fieldwork—rain, mud, and all— Raxworthy invited the video team from the Museum’s Science Bulletins multimedia program to accompany him and Ruane to Madagascar’s Anakarana National Park.

Rainy season aside, snake surveys are challenging to conduct. Snakes are shy and not abundant, the hardest reptiles to find during fieldwork. Madagascar’s snakes have been studied for decades, and still scientists estimate that many new species are yet to be described. Many of the described species still lack DNA samples or even recent confirmed observations. It’s those rarest 10 percent—the most elusive of an already hard-to-spot group, rarely seen and poorly documented—that Raxworthy and Ruane were after on this expedition.

To study snakes, of course, you first have to find them—but how? Some of the species at the top of Raxworthy and Ruane’s list are so little known that researchers lack the most basic clues — prey, behavior, habitat— about where to start. Instead, they use everything in their toolkit, including traps, including pitfalls, and repeated surveys at various sites and at all hours of day or night.

Snakes Madagascar
Snakes are shy and not abundant, the hardest reptiles to find during fieldwork. Raxworthy and Ruane use everything in their toolkit including repeated surveys at various sites and at all hours of day or night to find elusive species. 
© AMNH/Science Bulletins

“Searching at night is a good way to find snakes,” says Dr. Ruane, who has been catching snakes since she was five years old and bringing reptiles and amphibians home from weekend hikes in Pennsylvania with her grandmother. “At night, I’m looking in trees for arboreal snakes that are active only at night, and during the day most of the snakes I’m looking for are terrestrial, fast, so I might be scanning the ground and ready to pounce.”

It’s a tough gig, and not just physically. “It’s discouraging when you don’t find anything,” says Ruane. “But I just keep telling myself: I might find it if I look. I know I will not find it if I don’t look.” The team’s dedication ultimately paid off. Just what did Raxworthy and Ruane discover? Find out when the video segment about this trip begins screening this summer in the Hall of Biodiversity.

This research was supported by the U.S. National Science Foundation under Grant No. DEB 1257610.

This story is adapted from an article in the Summer 2014 issue of Rotunda, the Member magazine. 

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