Trying to make sense of raven chatter
Be careful what you say, crows. Doug Wacker is listening to you.
Wacker studies animal behavior at the University of Washington Bothell. Since August 2022 he has been in Fairbanks following crows. When he hears them singing, Wacker points to the large, black birds with a microphone attached to a plastic dish that looks like a giant contact lens.
Wacker is busy taking in as much raven talk as he can in Alaska’s second largest city. He wants to find meaning, if any, in the squawks, rattles and water drop/computer noises that so often come from those black mouths.
Many of Wacker’s recordings are the voices of members of the largest local congregation of ravens he has found so far — at the Fairbanks mound.
“I never thought I would be doing an academic sabbatical in a landfill,” Wacker said during a recent presentation.
Wacker wonders if there is any pattern to the series of sounds that come from a crow’s mouth. Over the years, researchers have identified up to 116 different vocalizations of crows.
Although scientists who study crows debate that number, William Boarman and Bernd Heinrich described a few types of specific calls in a crow description they wrote for the Cornell Lab of Ornithology’s Birds of North America. The distinct calls were begging, vocal play, predatory alarms, demonstrative calls, knocking, comforting sounds, chasing calls and mimicry.
Wacker now records the sounds of crows — and their current cohorts, bald eagles — at the Fairbanks Landfill 24 hours a day. He also records opportunistically at many other locations.
[From 2021: Anchorage Costco customers say ravens are stealing their groceries in the parking lot]
Wacker wants to further decode raven calls using machine learning, which he describes as using a computer to look for patterns.
He said people are biased in their descriptions of sounds, noting that scientists have described the same call crows use to announce they’ve found food as an aw, a kow, a ky and as a scream .
“We all call the same call something else,” Wacker said.
He looks at crow calls with spectrograms — visual displays with colored peaks and troughs that wash over his computer screen. This allows him to compare the sounds with his eyes as well as his ears. For example, he can measure with precision the length of a crow’s call and the time between syllables.
He hopes that as he uploads snippets of Fairbanks’ crow chatter, the machine-learning computer will separate crow calls into categories he wouldn’t have come up with on his own.
For now, Wacker taps his brakes and steps outside his car near Wendy’s, where he records crows talking about the traffic on Airport Way.
With the help of artificial intelligence, he might collect enough crow talk during his sabbatical to help us humans come up with a better idea of how our trash companions communicate.
This raises a question: Do we really want to know what crows say about us?