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Volume 90 Issue 17 | p. 48 | Newscripts
Issue Date: April 23, 2012

Robosquirrel Versus Rattlesnake, Inefficient Balloon Popping

Department: Newscripts
Keywords: biorobotics, robosquirrel, robotics, rattlesnakes, animal communication, Rube Goldberg, machine contest, engineering
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Death Match: Robosquirrel is ready to rumble with rattlesnake.
Credit: Andy Fell/UC Davis/Shutterstock
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Death Match: Robosquirrel is ready to rumble with rattlesnake.
Credit: Andy Fell/UC Davis/Shutterstock

First, there was “Mothra vs. Godzilla.” Then Alien took on Predator. Now, thanks to a team of researchers in California, another epic battle will play out between creatures worthy of a sci-fi film: Robosquirrel will square off against rattlesnake.

But instead of coming to a theater near you, this real-world face-off will take place in the rugged terrain outside San Jose. And the results will eventually appear in a scientific journal.

Researchers have been studying the predator-prey relationship between rattlesnakes and ground squirrels for decades. They’ve known that the rattlesnake diet consists mainly of ground squirrel pups and that when adult ground squirrels approach rattlesnakes, the furry rodents wag, or flag, their tails from side to side.

In 2007, a team of scientists observed that not only do the squirrels flag their tails at the snakes, but they also increase the temperature of their tails during the confrontation (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.0702599104). The reason for this complex behavior, however, is still unknown.

In this video, robosquirrel approaches a hiding rattlesnake and then either flags its tail or does nothing. The rattlesnake strikes the idle robosquirrel, indicating that the tail flag may warn the snake off.
Credit: Rulon Clark Lab

That’s where robosquirrel comes in.

To study animal communication with an experimental approach, “you have to have a playback design,” says Rulon W. Clark, a member of the California research team and expert on snake behavior. Playback design, he tells Newscripts, means having an animal signal that scientists can duplicate and manipulate. Robosquirrel provides a way of having that controllable signal, says Clark, who is a biologist at San Diego State University.

Clark and the rest of the team hope to use their robotic squirrel—a taxidermied outer shell with a motorized, heatable tail—to figure out the exact reason for a squirrel’s tail-flag signal.

They chronicled the development of robosquirrel and some preliminary field results in a late-2011 article in IEEE Robotics & Automation Magazine (DOI: 10.1109/MRA.2011.942121). So far, it seems that squirrels are heating and flagging their tails to warn the snakes that they’ve been seen and that their chances of ambushing the rodents are slim, the researchers say. “Rattlesnakes are one of the few organisms out there that can ‘see’ infrared light” with sensory organs on their noses, Clark says. So the reptiles can certainly detect the squirrels’ heated tails.

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Decidedly Inefficient: The St. Olaf team with its device.
Credit: Tom Roster
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Decidedly Inefficient: The St. Olaf team with its device.
Credit: Tom Roster

But, Clark adds, “we’ll need several more seasons in the field until we have enough data” to say for sure and publish. The researchers will head back out into rattlesnake territory to make some more observations in late May.


Speaking of epic battles, several teams of college students recently gathered at Purdue University to duke it out in the 25th annual Rube Goldberg Machine Contest. This year, the students were asked to build a device that takes at least 20 steps to pop a balloon in less than two minutes.

In this clip, students from St. Olaf College, in Minnesota, run their winning Rube Goldberg machine, which pops a balloon in 191 steps.
Credit: Courtesy of Jason Engbrecht/St. Olaf College

Typically, popping a balloon requires one step—insert pin into balloon—but the competition rewards engineering inefficiency, as well as creativity. So these devices, inspired by the whimsical contraptions dreamt up by Pulitzer Prize-winning cartoonist Rube Goldberg, include parts such as pulleys, levers, and lasers for completing a simple task.

Taking 191 steps to pop its balloon, the winning machine this year was built by a team at St. Olaf College, in Minnesota. Team cocaptain and chemistry-physics double major Justine N. Tawel tells Newscripts that the theme of St. Olaf’s device was the cataclysmic end of the world in 2012, as predicted by the Mayan calendar.

During the machine’s final step, a laser switches on to pop a balloon that looks like Earth. “That’s one of my favorite steps because I set up the laser,” Tawel says.

 
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