The Vulture Ecology Study: 2020 Update is part of the Golden Gate Raptor Observatory (GGRO) 2020 Pacific Raptor Report. It was authored by biologist Teresa Ely, GGRO’s Banding Manager and resident vulture expert. The GGRO has been a program of the Parks Conservancy for over 30 years, fulfilling their mission to inspire the preservation of California raptor populations. The full Pacific Raptor Report can be found on the GGRO publications page. If you'd like to support GGRO's great work, you can consider donating to the Conservancy here.
I have a fondness for Turkey Vultures that a lot of people do not have. You can almost feel the warmth of the sun when you see them perched with their wings outstretched in the morning. I like the way they seem to effortlessly soar through the sky, the fact that their gut can handle decomposing food, and if you watch them for long enough, they show natural curiosity. Simply put, they are cool.
When I took over the GGRO Vulture Ecology project from Chris Briggs, there was a steep learning curve in how to catch these birds. Over a couple of seasons, with the help of interns, a small volunteer support team, and collaboration with local rehabbers, we went from operating an unproductive chicken- carcass bow net at an active banding station, to a high-functioning cow-carcass-buffet walk-in trap located near Sausalito.
As we described in Pacific Raptor 39 and 41, our goal is to study Turkey Vulture movement ecology as well as rodenticide exposure. In addition to trapping vultures in the Marin Headlands, we have collaborated with two Bay Area rehabilitation centers, WildCare in San Rafael and Lindsay Wildlife Hospital in Walnut Creek. I have tagged some of their rehabbed vultures before they were released. Working with these two organizations has helped me to keep up my tagging skills (you must create a small puncture in the patagium to place the tag, similar to condors), as well as to provide information on vulture rehab success.
We started working with WildCare in 2017, and they generously donated a taxidermied vulture to the GGRO—named “Beatrice Bones”—to use as a decoy to attract vultures. This technique turned out to have a low success rate, but it was useful in the early stages of operating the walk-in trap. Below are the tagged vulture sightings by number.
LINDSAY WILDLIFE HOSPITAL VULTURES
373: This vulture was brought to Lindsay Wildlife Hospital in October 2018 after it was found in Clayton, CA, with a gunshot wound that caused broken wing bones. It underwent surgery and spent 107 days healing from its injury before it was released in February 2019. Resightings: 4
In early 2019, GGRO volunteer bander Lindsey Blessing was working with Lindsay Wildlife Hospital and helped us start tagging their rehabbed vultures in early 2019. After some modifications on our state and federal permits, we were able to borrow a live vulture decoy to hang out in our vulture walk-in trap. “Borrowing” is exactly what it sounds like. They loan us a Turkey Vulture just before it is ready to be released. The vulture sits in the large cage trap for a couple of days under close supervision, attracts vultures into the trap, then is returned for a check-up, receives its own tag, and is released.
MARIN HEADLANDS VULTURES
With the help of more “borrowed” vultures in the late winter of 2020, the Marin Headlands trap began to attract more vultures than we had previously been able to tempt. Just as we started attracting up to 10 vultures at once, but before the vultures figured out how to walk into the trap, the pandemic shut down our operations for most of 2020. The following vultures were trapped between 2017 and 2020.
When we were told that we had to shut down trapping operations in 2020, it was a huge disappointment, but this was necessary for safety. Along with the Bay Area shelter-in-place orders, there was a noticeable trend that began—bird- watching became more popular. I believe one reason that we’ve seen an uptick in our vulture resightings is because more people are out looking at birds.
The map that follows, made by GGRO volunteer Erin Fisher-Colton, shows the vultures that were resighted and reported to Bird Banding Laboratory in 2020. We’d hoped to see more movement for these birds, but it is not entirely unexpected that they remain “local.” During peak vulture migration times, we have had to close the trap due to smoke from nearby fires causing poor air quality in the Bay Area. The vultures we have tagged are outside the fall migration window, which might explain why we see these more local birds.
Our next steps include testing the blood samples for rodenticides and heavy metal presence. If conditions allow us to run the trap in the upcoming autumn, we hope to trap some birds that will migrate farther than Palo Alto. We also plan to continue working with WildCare and Lindsay Wildlife Hospital, and deeply appreciate the collaboration and skills of our colleagues at both institutions.