Written by: Cara Herrington & Gill Radcliffe from the University of Victoria & The Raptors

If you are attending the 2025 Raptor Research Foundation conference in Costa Rica, Cara will be sharing insights into conspecific grouping at nest sites during a lightning talk, on October 16th at 3:55pm.

The team will also be presenting two posters:

• migration variations: www.the-raptors.com/researchposter2.pdf
• recovering transmitters: www.the-raptors.com/researchposter3.pdf

Turkey Vultures in the Pacific Northwest

In much of the world, vulture populations are shrinking. But in the southern latitudes of Canada, and especially in the Pacific Northwest, one species of vulture is expanding. Over the past several decades, the Turkey Vulture (Cathartes aura, TUVU) has steadily pushed its range northward while simultaneously increasing in abundance in these newly occupied regions.

This expansion raised a big question for Gill Radcliffe, Research Director at The Pacific Northwest Raptors (The Raptors): what does life look like for TUVUs at the edge of their range, specifically Vancouver Island? While TUVUs are abundant further south, almost nothing is known about how they survive, move, and breed at this northwest frontier. [Vancouver Island, with its rugged coastline, temperate rainforests, and geographic separation from the mainland, presents a unique landscape for a soaring scavenger.]

To answer these questions, the TUVU Project launched in 2022. The Raptors partnered with the University of Victoria, and with support from a Mitacs Accelerate grant, graduate student Cara Herrington joined to help with the research goals. The team began outfitting vultures with CTT’s ES-400 solar GPS units. Since then, 13 vultures have carried transmitters, providing continuous insights into their locations, movements, and daily activity patterns.

Pheonix, Turkey Vulture Ambassador at the Pacific Northwest Raptors.

What We’ve Learned So Far

By 2024, our first detailed analyses were ready to share. Using GPS data, we examined home range sizes, activity patterns, and broad habitat use by TUVUs on Vancouver Island. While we continue to collect data and refine these analyses, some intriguing patterns have already emerged. A select number of breeding TUVUs in the region have expressed surprisingly small home ranges compared to what has been recorded elsewhere for the species. We also note a consistent decreasing trend in activity as the breeding season progresses. We shared these early results in a poster at the 2024 Raptor Research Foundation (RRF) conference in Charlotte, North Carolina. You can view the poster here: www.the-raptors.com/researchposter1.pdf

Nest Monitoring: An Additional Bonus

While our initial goals are focused on movement and migration, we knew the GPS data would offer something more: the chance to locate nest sites.

Since 2022, we’ve been passively monitoring several nests with cellular trail cameras. These cameras have provided fascinating glimpses into vulture family life. We've observed each stage, starting with early nest-prepping behavior, to egg incubation, to chick rearing. It has been incredibly rewarding to see the very birds we have fitted with transmitters not just survive but thrive by doing exactly what they should be doing biologically: raising their young successfully.

Perhaps the most surprising observations have been the regular conspecific congregation at multiple nest sites year after year. Seeing small groups of TUVUs gathering near active nests was not something we anticipated, and it raises exciting new questions about the social lives of the species.

With improved camera equipment, we hope to explore this behavior in more detail: Are these gatherings cooperative, opportunistic, or familial in some way? Do they influence breeding success?

Cara will be sharing our insights into conspecific grouping at nest sites during a lightning talk at this year’s Raptor Research Foundation conference in Costa Rica.

Aldo, fit with a transmitter in 2023, returning to nest cave to feed two chicks (top left).

Huxley, fit with a transmitter in 2023, departing nest cave.

Every Vulture Has a Story

One of the most fun parts of this project has been how quickly each vulture revealed its own “personality.” When we first started fitting transmitters it didn’t take long for us to realize that it’s nearly impossible to put these birds in a conceptual box. Each one is unique, and just when we think we know what to expect, they surprise us all over again.

Take Carson, for example. Carson seemed like a textbook migratory case at first: for the first two years with a transmitter, Carson flew an expected migratory route from Vancouver Island down to Durango, Mexico. But during the third year of tracking, Carson switched it up by cutting the journey in half and overwintering in California instead. Why? Age? Experience? A calculated gamble? We may never know, but it’s exactly the kind of curveball that keeps us guessing.

And Carson is far from the only surprise. Each bird we’ve tracked has shown us something new, whether it’s a quirky detour, a bold change in pattern, or an alternate strategy we hadn’t imagined. We’ll be highlighting a few of these individual movement stories in a poster at the upcoming RRF conference in Costa Rica. The poster can also be viewed here: www.the-raptors.com/researchposter2.pdf

Every year, we find ourselves waiting to see what these vultures will do next. It’s been a joy to follow them not just as data points, but as individuals carving out their own strategies.

Migration tracks of Carson. Year one and two shown on the left and year three on the right.

Recovering Trackers

Not every story has a happy ending, but even in loss there’s a chance to learn. Over the course of this project we’ve been faced with the loss of a few TUVUs, and while those moments are always difficult, they’ve also shown us something remarkable: we can recover units and try to understand what happened to each individual.

Some recoveries happen close to home on Vancouver Island, where we can respond quickly to a motionless transmitter. But others unfold thousands of kilometers away, on the wintering grounds in Mexico. Two of the most memorable examples are Mendes, recovered near Culiacán, and Humboldt, recovered near Michoacán. In both cases, international collaborators stepped in to investigate, retrieve the transmitters, and share what they saw on the ground.

Being able to say that we’ve successfully recovered downed birds and transmitters both locally and internationally is a huge milestone for this project. It means we’re not just learning from the birds while they fly but also gaining insight into the challenges they face when they don’t make it. It also means the transmitters themselves get a second life, as their recovery allows them to be redeployed to tell the story of another vulture.

These recoveries have underscored the importance of collaboration, from local field checks on Vancouver Island to global networks of biologists and citizen scientists. Each recovery, while bittersweet, keeps the project moving forward and strengthens the community of people invested in these birds.

You can hear more of these stories of recovery which will be presented in a poster at the upcoming RRF conference. You can view the poster here: www.the-raptors.com/researchposter3.pdf

Tracker recovered off of Mendes, near Culiacán, Mexico.

Tracker recovered off Darwin near Duncan, Canada. Darwin was still sporting and older 3G model.

Crossing of the Juan de Fuca Strait: A Migration Bottleneck

Fall migration on Vancouver Island brings a new level of challenge for the TUVUs than summer there. Before they can reach the mainland, these vultures must cross the Juan de Fuca Strait, a 20 km stretch of open water which separates Vancouver Island from the continent. For soaring birds that depend on thermals, this is a formidable barrier.

On the southern tip of the island, TUVUs gather in large kettles, sometimes numbering in the hundreds or even thousands, waiting for the right weather before crossing together in dramatic groups toward the mainland. This creates an awe-inspiring ecological spectacle!

To understand what conditions make these crossings possible, we are pairing GPS tracking data with on-the-ground observations collected by a team of dedicated volunteers at the staging area. This combined effort allows us to link weather conditions with actual crossing events, helping us answer the critical question of how these vultures navigate this barrier. This work will place this unique phenomenon in the global context of other migratory barriers faced by birds around the world.

The beautiful but risky crossing of the Juan de Fuca Strait looking from Vancouver Island towards the Olympic Mountains of Washington.

A group of Turkey Vultures preparing to cross, Sept 2023.

Crossing tracks of multiple vultures as they navigate the barrier of the Juan de Fuca strait during fall migration.

Looking to the Future

Over the last three years, we have seen intimate views inside nest sites, the individuality of birds carving out their own migratory paths, and the challenges of bird loss and transmitter recovery. We’ve watched TUVUs gather by the hundreds at the edge of the Juan de Fuca Strait and linked dramatic water crossings to weather conditions. And we’ve seen that each bird we follow adds its own unexpected twist to the story.

It’s clear that TUVUs are not only surviving here on Vancouver Island, they are also thriving. That’s something worth celebrating in a time when so many vulture species worldwide are in steep decline. This project continues to evolve with every new data point, every recovery, and every season in the field. These birds keep surprising us, and that sense of discovery is what makes this work both inspiring and important.

We’re glad to be documenting their success, and we look forward to learning from them for many years to come.