A 30-year “snapshot study” of birds in the Pacific Northwest is showing their surprising resilience in the face of climate change. The project started when School of Biological Sciences Assistant Professor Benjamin Freeman found a study by Louise Waterhouse detailing birds in the mountains near Vancouver three decades ago. What followed was an ecological scavenger hunt: Freeman revisited each of the old field sites, navigating using his local knowledge and Waterhouse’s hand-drawn maps.
Freeman, who grew up in Seattle, mainly studies the ecology of tropical birds — but the discovery of Waterhouse’s paper made him curious about research closer to home. The results were surprising: over the last three decades, most of the bird populations in the region were stable and had been increasing in abundance at higher elevations.
The study, “Pacific Northwest birds have shifted their abundances upslope in response to 30 years of warming temperatures” was published in the journal Ecology this fall. In addition to lead author Freeman, the team also included Harold Eyster (The Nature Conservancy), Julian Heavyside (University of British Columbia), Daniel Yip (Canadian Wildlife Service), Monica Mather (British Columbia Ministry of Water, Lands and Resource Stewardship), and Waterhouse (British Columbia Ministry of Forests, Coast Area Research).
“It is great news that most birds in the region are resilient, and by doing this work, we can focus on the species that do need help, like the Canada Jay, which is struggling in this region,” Freeman says. “Studies like this help us focus resources and effort.”
Songbirds and snow
Conducting the fieldwork was a detective game, Freeman says. Each day, he would wake up at four in the morning to locate and visit the research areas — often navigating trails, open forest, and rough terrain on foot.
This area of the Pacific Northwest is punctuated with old-growth stands of trees — sections of forest that have never been logged or altered. “These areas feel like islands,” Freeman shares. “They feel ancient and untouched, but even in pristine habitats, birds are still responding to climate change.”
Most of the work was conducted during the birds’ breeding season, from late May into June. This is when the birds are most vocal, which is ideal for surveys, Freeman says. The downside? Even in June, there is often snow in the mountains. “I was out at dawn, hiking through snow in the freezing cold, wondering why I didn’t stay in bed,” he recalls. “But then I’d hear birds singing all around me and realize it was all worth it.”
Upward expansion — and resilience
By comparing the two “snapshots,” the team showed that while temperatures have increased over the last 30 years, most bird populations in the region haven’t declined — but they have become more abundant at higher elevations. “It’s encouraging,” Freeman says. “Thirty years of warming has led to changes, but for the most part, these bird populations are mostly stable or improving.”
One reason for this resilience could be the stability that old growth forests provide, and Freeman suggests that conserving wide swaths of mountain habitat might help birds thrive as they continue to adapt, while still supporting populations at lower elevations. The study also helps identify which bird species need additional support, like the Canada Jay — a gray and white bird known for following hikers in pursuit of dropped snacks.
It’s just one piece of Freeman’s larger research goal — he aims to do this type of snapshot research in many different places to identify general patterns, especially differences in temperate versus tropical environments.
“In the tropics, most bird species are vulnerable, with only a few resilient species. In the Pacific Northwest, we saw the opposite,” he says. “A pattern is emerging: temperate zones show more resilience, tropics more vulnerability.”
Freeman is also conducting research with a group of students in Northern Georgia. “We predict that these Appalachian birds will be resilient as well,” he says, “but we need to study and understand what’s happening in nature — not just make predictions.”
DOI: https://doi.org/10.1002/ecy.70193
Funding: Packard Foundation
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The Canada Jay is one of the birds struggling in the Pacific Northwest. (Credit: Mason Maron)
A placard still standing from the original surveys conducted in the early 90's. Finding these original sites was a "scavenger hunt," Freeman says. (Credit: Benjamin Freeman)
A large downed cedar tree in one of the lowland old-growth forests that Freeman navigated. (Credit: Benjamin Freeman)
Townsend's Warbler, a small songbird that lives in the forests of the Pacific Northwest. (Credit: Melissa Hafting, @bcbirdergirl)
While locating the field sites, Freeman spotted this bear on an old road. (Credit: Benjamin Freeman)
An overgrown and abandoned road that Freeman traversed. (Credit: Benjamin Freeman)
The Varied Thrush is another bird common in the Pacific Northwest. (Credit: Melissa Hafting, @bcbirdergirl)
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Written by Selena Langner
