How Sleepy Are Sloths and Other Lessons Learned
Smithsonian scientists use radio technology to track animals in an island jungle in the middle of the Panama Canal
- By Megan Gambino
- Smithsonian.com, February 03, 2010, Subscribe
(Page 2 of 2)
The next day, I meet with Ben Hirsch, a post-doc who has just come off of two consecutive nights of trapping and tagging ocelots. He has been working on a project that uses ARTS to study the interactions between ocelots, rodent-like agoutis and the seeds from an island tree called Dipteryx. The agoutis eat some of the seeds and bury others for later. But ocelots prey on the agoutis, thus allowing some of the buried seeds to grow into trees. Hirsch and his colleagues are studying how the balance between the three species is maintained. He takes me to the ARTS lab, in one of the central buildings of the field station, and shows me a computer from which all the tagged animals can be traced. Like a hospital monitor, each jagged line on the screen represents an animal. The color of the line, Hirsch explains, corresponds with the animal’s location on the island; the more drastic the line’s spikes, the more active the individual is. He opens a drawer full of collars, ranging from agouti- to jaguar-size. Swimming amongst them are a few un-collared radio transmitters. I’m reminded of what Kays told me about researchers having to get creative. They glue transmitters to animals too small for collars, like bats. For anteaters, which don’t exactly have a neck, they tried harnesses, but ended up gluing the transmitters to their back ends, out of reach. Of course, depending on the method, a tag can last for mere days to over a year.
Occasionally, scientists at BCI will use GPS tags, an alternative to radio transmitters. And while they do produce a reliable location of the animal, they are expensive, don’t produce live data and are too large to use on many animals. One of the biggest breakthroughs with the radio transmitters is their size. The smallest weighs 300 milligrams—less than a third the weight of a single paper clip—and can be adhered to monarch butterflies and tiny bees. Horan, my hiking companion, has used them to track tree frogs.
ARTS has led to some surprising discoveries. A research team led by Niels Rattenborg, of the Max Planck Institute for Ornithology in Starnberg, Germany, found that sloths aren’t as slothful as originally thought. In captivity, they tend to sleep about 16 hours a day. But in the wild, they average only 9.6 hours.
Behavioral ecologist Meg Crofoot, who currently directs ARTS, uses the system to study white-faced capuchin monkeys. She has learned that when it comes to fights between social groups, victory does not depend on numbers. Regardless of group size, the monkeys closer to their home turf when the battle breaks out are more likely to win.
“ARTS is letting us get at questions that previously just haven’t been answerable using traditional field techniques,” says Crofoot.
Previously, Crofoot would have needed a small army and a massive budget to follow multiple groups of monkeys simultaneously. For this reason, very little is known about competition between social groups. But ARTS was “a new way of getting at this data.” She tagged one or two individuals in six social groups that inhabited the island and was able to trace their every movement. When she wanted to watch a group’s behavior, she could go to the lab, find out where the monkeys were and get there—a huge timesaving measure.
Of course, like any complicated system, ARTS has its kinks. According to Kays, the biggest challenges are keeping the hardware and towers functioning in such a humid environment—vegetation grows on the towers and antennas rust—and studying the sheer amount of data brought in. In the future, he hopes to find a way to automate the data analysis and increase the number of tagged animals the system can handle. Smaller transmitters, for even more insects, he says, wouldn’t hurt either.
“There are so many species that are interacting and doing interesting things,” says Kays. “Coming up with ideas for studies is the easy part.”
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Comments (3)
I have a biology degree from the uk and I would like to research soths in Panama. I would like to ask if their are any scientists from the research in Boco or Panama City that I can speak to about this. I am coming over in October to see if I can come in and meet and chat with a few people in Boco and Panama City.
I am also happy to help out on other projects.
The above also has given me the drive to finish my thesis for submission 15th November.
Posted by Karen Wilkins on July 24,2011 | 06:42 AM
Interesting.
The story uses the phrase "rodent-like agoutis" which implies agoutis are similar to rodents but not rodents. But that's incorrect; agoutis are true rodents, in the family Dasyproctidae. There are about 10 species of agouti, all of which are found only in the Western Hemisphere.
The closest relative to the agouti is the acouchi (two species), which is in the same family and which is the only other type of rodent in the family. Acouchis, which look very similar to agoutis, may be seen in the Small Mammal House of the National Zoo.
Posted by Jack Manischewitz on January 19,2011 | 12:29 AM
This is amazing! I am a Biology student in search of a direction and reading articles like this one inspire me to no end.
Posted by Molly Dieterich on February 6,2010 | 12:11 PM