I’m happy to finally share the results of a massive collaborative effort: the removal of Barred Owls from the Sierra Nevada. It is not an exaggeration to say that this averted the near-certain extirpation of California Spotted Owls from the core of their range. My now-former UW-Madison labmates Danny Hofstadter and Nick Kryshak led the removal effort in conjunction with Brian Dotters of Sierra Pacific Industries. We found that following one year of removals, Barred Owl site occupancy fell from 0.19 to 0.03. Importantly, Spotted Owls recolonized 56% of their formerly occupied sites within one year. This demonstrates that landscape-scale invasive species removals can be achieved efficiently.
This project is a somewhat rare conservation success story, and that it really gives meaning to my dissertation work. The removal effort was a direct outcome of my early-2020 paper documenting the rapid population growth of Barred Owls in the northern Sierra Nevada. Sounding the alarm on a conservation crisis isn’t enough – we need to act on our findings.
In the early 1900s, flooding near the town of Anaconda, Montana washed toxic mine waste through over 100 miles of the headwaters of the Clark Fork, the largest river in Montana. In response, the mining company built a series of retention ponds which have since sequestered pollutants and become a major hotspot of migratory waterfowl. The site is now owned by a subsidiary of BP, which contacted KLY-CCB to initiate acoustic monitoring at the ponds.
I traveled there in early September to set up an array of SwiftOnes and game cameras to provide audio and photo data to compare to bi-weekly bird counts. The goal is to measure avian diversity and waterfowl abundance. However, an important ingredient for passive acoustic surveys is animal sound – and that was rather lacking. Fall is always a quiet time of year for birds, but a combination of high temperatures, strong wind, and heavy smoke from two nearby wildfires gave the ponds a decidedly subdued atmosphere. I did identify Sandhill Cranes, Western Meadowlarks, Black-billed Magpies, and Marsh Wrens with the BirdNET app (free for Android and iOS!), and I saw many hundreds of Coots….which were silent and many hundreds of meters from the edge of the pond. Nonetheless, the density and duration of our sampling plan makes me confident that we’ll be able to turn some interesting acoustic and quantitative challenges into a useful analysis of the relative contribution of artificial habitat features to local and regional biodiversity. Stay tuned…
At the end of March I went out to the Sierras to start a new project: conducting the first ever acoustic surveys for the federally endangered Yosemite Toad. Check out THIS SHORT VIDEO I made about the trip.
I’m excited to share two new papers related to acoustic monitoring of bird bird communities!
‘BirdNET: A deep learning solution for avian diversity monitoring‘ by Stefan Kahl, me, Maximilian Eibl, and Holger Klinck was published in Ecological Informatics.
‘Survey coverage, recording duration, and community composition affect observed species richness in passive acoustic surveys‘ by me, Stefan Kahl, Phil Chaon, Zach Peery, and Holger Klinck was published in Methods in Ecology and Evolution.
The Ecological Informatics paper (available HERE) provides a technical description of a new machine learning algorithm, BirdNET, which can identify 984 bird species by sound – over 95% of the species found in North America and Europe. It was trained with ~1.5 million weakly labeled samples and validated with focal recordings, fully annotated data, and over 33,000 hours of soundscape data recorded at an eBird hotspot. The key performance metric is “mean average precision”, which was 0.79 – meaning that most predictions for most species are correct. If you have any questions about BirdNET, I encourage you to contact Stefan. I’d also like note that there is a free BirdNET app available for iOS and Android, and the current species count is about 3,000.
The MEE paper (available HERE) draws on simulated bird communities as well as soundscape data from the Sierra Nevada (1,000 hours) and the Cornell Lab of O’s Sapsucker Woods (750 hours) which we analyzed with BirdNET to evaluate how different passive acoustic survey designs affected observed species richness. In short, rarefaction curves indicates that longer recordings are better, but by 28 hours (4 hrs at dawn per day for 7 days) species richness is increasing very slowly. Species composition and environmental heterogeneity have important implications for survey design as well. An ancillary finding with exciting implications for our upcoming work is that we identified over 100 species in the Sierra Nevada with just a week’s worth of data at 28 locations. If you have any questions about this paper, please contact me.
Our research group, the Center for Conservation Bioacoustics, recently hosted a “virtual visitors center” for the Lab of Ornithology. I presented a bit about my work in the Sierras, Daniela Hedwig and Bobbi Estabrook talked about the Elephant Listening Project, Isha Bopardikar talked about finless porpoises (yep, that’s a real thing), and Aaron Rice talked about snapping shrimp. What made the even really special was the host, wildlife DJ and Cornell PhD student Ben Mirin, who makes music with animal sounds!
We each briefly discuss our work and then we did live Q&A. There were about 700 live viewers, and the video has over 14,000 views! Check it out:
My collaborator Dr. Stefan Kahl and I gave a brief presentation about the artificial intelligence tool BirdNET at a recent Lab of O. team meeting. We focus on the BirdNET app, but the underlying algorithm is what I’ll be using to study the Sierra Nevada bird community.
On April 21st I successfully defended my dissertation, and on April 23rd I left Madison for points east; in early June I’ll be joining the Cornell Lab of Ornithology as Rose Postdoctoral Fellow!
The remote defense was disappointing – I would’ve liked to shake my advisor’s hand and hug my parents – but it certainly had its benefits. A lot of friends and colleagues watched my presentation that wouldn’t have otherwise been able to attend, and it I’m very grateful to all that joined in. The recording is HERE if you’re curious.
At the Lab of O., I’ll be in the Center for Conservation Bioacoustics, a great team with whom I’ve worked throughout my PhD as well. I’ll be using the Sierra Nevada audio data my crews have been collecting since 2017 to study the entire diurnal bird community! The artificial intelligence program BirdNET, one of the CCB’s newest products, will be an integral tool in this new project. BirdNET is an convolutional neural network that can identify almost a thousand bird species.
This next phase will certainly be a team effort, as was the last. A huge team helped make my dissertation possible, and working with them was truly one of my favorite aspects of the project. I was lucky to have great technicians, including Nick Kryshak and Michaela Gustafson, and a number of academic and agency collaborators. And I couldn’t have asked for a better advisor. Thanks everyone.
Little is known about barred owl dispersal patterns in western North America, and I am a co-PI on a new project that is designed to fill that knowledge gap. The work – led by UW-Madison graduate student Whitney Watson – is taking place in California’s coastal redwood region, where barred owl densities are high relative to the Sierra Nevada, but still below what is thought to be their carrying capacity.
Recently, seven of us headed out from Madison to Mendocino county to capture and GPS tag adults. That data will inform acoustic surveys we will be conducting in the area and will help lead us to nest sites later in the season. We caught five birds in the first four nights, which is as many as we caught in each of two whole seasons of work in the Sierra. I suspect this is a function of density: there are (many) more birds to target, and they respond more aggressively to decoys because territorial interactions are more common. Interestingly, they were all more docile in-hand than the Sierra birds.
Gizmodo did a story on my paper showing rapid barred owl population growth in their ‘Earther’ section. Check it out HERE. There are direct quotes of my imitations of both spotted and barred owls, which makes me think I should stop hooting whenever someone asks what owls sound like.
The Wildlife Society also did a story on the paper, which you can read HERE.
I was a guest on Scientific American’s podcast ’60-Second Science.’ If you’d like to hear me hoot like a barred owl – or want a quick summary of my paper about barred owl population growth – check it out here.