7/21/2019 Bioacoustics in Birdland

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Varied thrush. Photo credit: Adam Hadley (PhD student, FES).

Bioacoustics in BirdlandHow computer scientists and wildlife ecologists are changing the way welisten to the environment

By Bryan Bernart 

It’s 3:00 . While many of us are fast asleep,for a field researcher taking a bird census, theday has already begun. For the next severalhours, he or she will hike many miles, stoppingfor 10 minutes at each site to listen for, and thenidentify, bird calls. Te next day, and for every dayfollowing it, the process is the same.

“Honestly, it takes a lot of effort,” saysMatt Betts, an associate professor of forestwildlife landscape ecology. “It’s a highly skilledoccupation; there aren’t many people who can dothis kind of job.”

Even some who are trained for it will not end

up working in the forest. “Tere are a lot moreinteresting things to do in ecology than standaround and count birds,” Betts notes. “With thatin mind, we came up with the question, ‘Can weautomate this process?’”

Te answer arrived in 2008 following theformation of the OSU Bioacoustics Group.Te group comprises a number of scientists,including students, faculty, and outsidecollaborators, hailing from such disparate fieldsas ecology, electrical engineering, computerscience, and marine resources. Its aim hasbeen to solve ecological problems using toolsfrom mathematics, as well as to discover newproblems in mathematics due to the necessity ofsolving environmental issues.

With such a broad scope, why study birds,specifically? “Birds are often excellent indicator

species—the canaries in the coal mine, so tospeak,” Betts explains. As is the case with frogsand amphibians, the health of a bird populationcan say much about the rest of an ecosystem.Tus, it would be useful to have an effective

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means for studying bird populations, especially ifit doesn’t involve time-consuming and arduousfieldwork.

Tis is where Forrest Briggs, a PhD student inComputer Science at OSU, and other members ofthe group come in. A 2006 graduate of HarveyMudd College, Briggs has been working to develop

software capable of identifying species of birdsusing recordings of their songs collected in thefield and uploaded to a laboratory computermany miles away. Birds can be classified usingalgorithms. Briggs explains that an algorithm“is a step-by-step, unambiguous sequence ofinstructions for how to accomplish a particulartask. A cooking recipe, for example, is analgorithm.”

By using machine learning, a sub-field of

artificial intelligence, algorithms can, throughexposure to many different instances of birdsong, be made more effective in classifying thebirds present in those recordings. An algorithmdoes this by analyzing the spectrogram thatis generated when a recording is representedvisually, allowing properties such as frequency,length, and amplitude of the sound to beobserved. Te algorithm compares results with

other human-expert-labeled examples to make aprediction based on similarity.

It is simpler to classify other animals than itis to classify birds, says Betts. For example, it’seasy for an algorithm to identify a single speciesof cricket because a cricket will chirp at a certain

frequency. “With birds, it’s more difficult. Teirsongs are intricate, and when multiple speciesare audible, they will even sing over each other,”he says. “Because of the many variables involvedin this study, the algorithms we employ arecomplex.”

At present, the Bioacoustics Group is using 16microphones in the H.J. Andrews ExperimentalForest in order to capture birdsong recordings,and would like to expand the study over a larger

area. Betts envisions 24-hour surveillance of birdpopulations, which would enable researchersto know precisely when birds enter and exit asite, and, when analyzed alongside other data,including environmental and climatologicalchanges, why they do so.

In a few years, a form of this technology mayeven become available to citizen scientists whoare interested in bird ecology. “People have a lot

of affinity for birds,” says Betts. “We’d like to havean iPhone app that would use our technology toallow citizen scientists to classify birds in theirown backyards, or in locations around the world.Tat’s a really exciting possibility.”

Researcher Sarah Hadley (PhD student, FES) is using thisinstrument to monitor bird sounds in the forest. Tistechnology is far more effective than any available before.Photo credit: Forrest Briggs.

Clark’s nutcracker pulling seeds from a whitebark pine cone.

Photo credit: Rebecca Brenton (‘, NR; post-bacc, FM).Brenton is currently working on the fish bio crew for theUSDA Forest Service, iller Ranger District, Umpqua NationalForest.