Black vultures roosting in the Sonoran Desert of Arizona.
11-14 January 2014
By Keith Bildstein, Ph.D.
Sarkis Acopian Director of Conservation Science
The road survey we scheduled for January 11 was scheduled to begin at 9 AM in Gila Bend, Arizona. Because we had overnighted in Casa Grande at the end of the previous day’s count, we set out for Gila Bend–an hour’s drive west on Interstate 8–just before 7 AM. Twenty minutes down the road, I noticed several black dots festooning a Saguaro Cactus “forest” 50 meters north of the interstate. Jean-Francois slammed on the brakes and we backed-tracked 100 meters or so along the shoulder to have a closer look.
The black dots were just what we hoped: Black vultures. Actually, a lot of Black Vultures.
We counted 208 spread across an area of 5-10 acres. Almost certainly there were more, as the landscape sloped down and out of sight, away north of the highway. We took a GPS reading, hopped back in the vehicle, and continued on. Even before we had begun our official count for the day we had 20 times as many vultures under our belts than the previous three days combined.
The 166-mile route itself, which took us through the quaint town of Ajo and the enigmatic town of Why, produced an additional 27 black vultures, including a flock of 17 individuals soaring over the Tohono O’Odham Nation town of Sells. Although we had a great day in the field we had not seen any turkey vultures. The next day, we assured ourselves, would be better.
And indeed it was, both in terms of vultures and scenery. We began as always at 9 AM, this time in the crossroads of Three Points, Arizona, south of Tucson. Our route for the day included extensive mileage in both the Buena Vista National Wildlife Refuge and the Coronado National Forest, both of which produced some of the best views seen during our time in the state. It also produced sighting of five turkey vultures and four black vultures, almost all of which were seen near the twin towns of Nogales–one each in Arizona and Mexico–both of which are renowned among birdwatchers for their landfills.
The day confirmed what was becoming a predictable pattern: The vultures were searching for food in human-dominated rather than natural landscapes.
Our final day of road surveys on the 13th would be our longest, 192 miles through Cochise County in the southeastern corner of the state. The route, which hugs the border with Mexico west of Douglas, Arizona, and passes directly through the Old West town of Tombstone, yielded but a single turkey vulture. And once again, the bird was seen near a town.
Overall we had seen only a few dozen turkey vultures during six days of surveys that covered more than 1,100 miles … far fewer vultures than we had hoped. Equally importantly, we had not found a potentially viable winter trapping site for the species, something we had hoped to accomplish as part of the grander scheme of things. We still had one day left before our flight to Hawk Mountain on January 15, and we decided to spend it by paying a visit to a rather special turkey vulture called “Jennie.”
Named in honor of former Hawk Mountain trainee Jennie Duberstein, the scientist-educator for the U.S. Fish and Wildlife Service, and the individual who organized logistics for our successful vulture trapping last May, “Jennie” was the only one of six satellite-tagged birds who had not decided to overwinter in Mexico or Central America. Although she had flown south almost 300 kilometers into Mexico in October 2013, “Jennie” inexplicably hastily returned to Arizona shortly thereafter and since had remained.
“Jennie” (on right) roosting in a large tree behind the high school in Gila Bend.
An email to GIS specialist par-excellence David Barber, back at the Sanctuary revealed that “Jennie” had spent the three previous nights in at a town park in Gila Bend, adjunct to the high school there.
We were in Tucson on the night of January 13, and at 5:45 AM the next morning we started with the plan to be there shortly after dawn. We arrived at the high school at 8:10 AM, turned the corner to circumnavigate the park, and saw our first perched turkey vulture. As luck would have it, it was “Jennie.”
Within seconds she flew off 200 meters and re-perched in an exotic tree we had seen the night before on Google “Street View.” Her antennae and satellite tracking unit were just where we had placed them more than 8 month earlier, firmly attached with Teflon ribbon back-pack style between her shoulders. Seeing “Jennie” alive and well was a capstone treat for Jean-Francois and me, but more importantly, “Jennie” was part of a roosting assemblage of at least 60 other turkey vultures. Without “Jennie” we would not have found this roost, which we actually had passed within a mile of twice during our previous six road surveys. Most likely this turkey vulture assemblage was feeding nearby, perhaps at one of Arizona’s many industrial-sized dairy farms.
Several of “Jennie’s” friends roosting at the high-school athletic fields.
The next step is to determine where these roosting vultures are feeding. Once done, we will begin to plan for next winter’s trapping effort. In the meantime, we need to start planning for our springtime trapping, during which we hope to trap and place tracking units on up to six additional turkey vultures. Tracking Arizona’s turkey vultures along with dozens of others from elsewhere in the U.S., Canada and Argentina, is helping us to learn more about the movement ecology of the world’s most common and widespread obligate avian scavenger, a type of bird of prey that ranks globally as the most endangered of all raptors.
To become part of Hawk Mountain’s support network for this significant research, call or email me at 1-570-943-3411 ext. 108; and Bildstein@hawkmtn.org