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Hide & Seek: Trailing Squirrels with Radio Telemetry

by Jennifer Amie

The Bell Museum's neighborhood gray squirrel population boasts a number of oddities, from a bevy of albinos to an unusual duo equipped with antennae. One particular pair, known as squirrel No. 701 and squirrel No. 742, sport watchband-like collars that sprout four-inch lengths of flexible wire. The garb is part of a radio telemetry tracking device, and the squirrels are (seemingly oblivious) participants in a scientific experiment designed by University faculty and Bell Museum education staff and executed entirely by elementary and middle school students.

Dubbed "The Secret Lives of Squirrels," the program is now in its pilot phase and will be launched in its entirety this summer. Its aim, says museum educator Christopher Goodwin, is to give kids a chance to participate in real science-from formulating a research question to devising an experiment to collecting and analyzing data.

The program kicked off in September 2004 when Goodwin and University professor James L. David Smith set out wire traps baited with oatmeal and peanut butter to attract a pair of subjects. Within 30 minutes they had recruited two squirrels, a male and a female, who were briefly treated with an ether-like anesthetic while their radio collars were attached.

The collars are equipped with tiny, battery-operated transmitters. "Each collar has its own frequency and is like a miniature radio station that transmits a 'beep, beep, beep' rather than news or top 40," says Goodwin. The range of each transmitter is 10 miles.

Using a tall antenna and a receiver the size of a cigar box (see photo), school groups and summer campers can locate the squirrels and record their whereabouts. Recently, a group of kids was hot on the trail of No. 701, taking turns holding the antenna and listening to the incoming "beeps" on headphones. By following the signal as it grew louder and louder, they got close enough to the squirrel to spot it in a nearby tree.

Once a squirrel is sighted, its location is marked on an aerial photograph of the museum grounds and nearby buildings. The coordinates are entered into a database that tracks the squirrels' locations over time, in various seasons and weather conditions, and at different times of day. Cumulatively, these data can be used to generate maps of the squirrels' territories.

With this information, students can pose and test research questions, such as whether male or female squirrels have larger territories, or whether the size of territories varies depending on weather, temperature, or season.

"In a couple of years, when we have a whole bunch of data and have established the territorial boundaries for different squirrels, we can add to the experiment," says Goodwin. One possibility might be to install a feeder within one squirrel's territory and then to observe whether a new food source causes other squirrels to invade.

The original pair of collared squirrels vanished in March 2004 (they have since been replaced by another pair). Their disappearance coincided with the appearance of bands of juvenile squirrels born that season. "It may be that older squirrels are displaced by younger squirrels once new litters are weaned," says Goodwin. "That's another question our data may help answer..

The mapping software used to record and analyze tracking data was developed in the University's College of Natural Resources, and fittingly, the technology used in this program was developed at the University of Minnesota. Radio telemetry was invented in the late 1950s and early 1960s by Bell Museum scientists John Tester, Dwain Warner, and Larry Kuechle. "It wasn't until 1959 that transistors became available which made radio telemetry possible," recalls Kuechle, who now runs an Isanti, Minnesota business that manufactures telemetry equipment. "Before that, you couldn't power anything very long with a battery."

Kuechle, Warner, and Tester developed the new technology and tested it on foxes, raccoons, skunks, ruffed grouse, and owls at the University's Cedar Creek Natural History Area. Since then, it has been used all over the world. "We can outfit the largest elephant or the smallest songbird," says Kuechle. "We can build a transmitter that weighs no more than six tenths of a gram."

Although scientists have used radio telemetry to study everything from tigers to salmon, there is little, if any, research pertaining to gray squirrels, which are too common to have attracted much attention. Their ordinariness, however, makes them an ideal subject for an educational program. "Urban kids are familiar with squirrels," says Goodwin. "This project can give them a sense that science happens everywhere, not just in wild or exotic places." Furthermore, squirrels are readily available for study, and they tend not to stray too far afield, making them easy to track on foot.

"We're finding that their territories are about twice the size of the Bell Museum grounds," says Goodwin.

This and other findings may one day be published in a scientific paper, says Goodwin, who expects the students' data to yield legitimate scientific results over time. Though conducted at every point by students, this is real scientific research-and that's what makes this program special. "At no time is the scientific process turned over to professional researchers," says Goodwin. "The kids are the scientists, from start to finish."