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Student researchers channel their inner wolves

October 02, 2017

On a summer night with a northerly wind, you might have heard a long, low howl drifting across the Carthage campus. If it stiffened those proverbial hackles on your neck and sent you scurrying outside to check on kids or pets, Caitlin McCombe ’20 thanks you for the compliment. Because that suggests her wolf impression was pretty convincing.

Caitlin honed her howling ability through lots of practice. She and fellow biology major Cara Hull ’19 studied wolf vocalizations through the Summer Undergraduate Research Experience.

They spent a month in the field with Angela Dassow, an assistant professor of biology. Her research examines vocal communication systems in a variety of species.

On a network of moonlit roads in central Wisconsin, the trio recorded gray wolves’ howls, barks, and yips for analysis. They crisscrossed an area roughly midway between the two students’ hometowns; Cara is from Colby in the northern part of the state, Caitlin is from Cedarburg in the southeast.

Howling at the moon

This spectrograph shows the audio properties of a gray wolf's howl in central Wisconsin.This spectrograph shows the audio properties of a gray wolf's howl in central Wisconsin.By howling themselves, they could trigger a sort of call and answer to elicit more sounds from the wilderness. That works better than playing back an actual recorded howl, they explained, because wolves can detect the difference on all but the most expensive equipment.

“It was really cool to get a response every time I howled,” Caitlin said.

With a naturally low-pitched howl and outgoing personality, she’s the consensus alpha wolf. Cara, the more reserved of the two, said she produces a high-pitched sound more “like a pup that’s trying really hard.”

They howled and recorded at night, when the wolves were active, stopping at eight to 10 locations at least a mile apart. Retired wildlife biologist Dick Thiel, who launched Wisconsin’s wolf recovery program nearly 40 years ago, briefly joined them.

In the daylight hours, the Carthaginians scouted for prime locations while their nocturnal subjects slept. Typically, that meant looking for tracks or feces.

Consistently putting in 14- to 18-hour days, the team would eventually crash at the Sandhill Wildlife Area — in a modest dormitory nicknamed the “Sand Hilton”. So, what did the SURE students’ think of their first dive into the less-than-luxurious world of field research?

“It was probably one of my best summers ever,” Caitlin said.

Returning to campus, they used Adobe Audition and other software to analyze the audio files. After filtering out ambient noise, they could plot the frequency, duration, and amplitude of the vocal sounds they recorded. Those offer clues to each wolf’s age, size, and social status.

Prof. Angela DassowProf. Angela DassowThe project is scheduled to run for two more summers. In part, Prof. Dassow hopes to identify individual pups and track their vocal development.

Real-world applications

Ultimately, she said the research could create an inexpensive, user-friendly method for wildlife biologists to survey the wolf population. It’s also non-invasive, in contrast to the trap-and-collar technique most commonly used now.

A federal court decision in 2014 restored the gray wolf’s protection under the Endangered Species Act, and the Wisconsin population has reached its recorded peak.

“Fifty years ago, we would’ve had to go to Minnesota or Canada to do this,” Prof. Dassow said.

Cara plans to pursue a graduate degree with an ecological bent, while Caitlin has her sights set on marine biology. Both agree the SURE project reinforced their enthusiasm for research.

More than 50 Carthage students covering all three academic divisions completed 10-week original research or scholarly projects with faculty mentors through SURE last summer. Selected participants receive a stipend, on-campus housing, a meal plan, and a research budget.

Hear their audio recording of a wolf howl