GPS transmitters confirmed the route taken by seven of the critically endangered birds in a three-hour aerial tour north.
Maggie Fusek, Patch Staff
|Updated Fri, Sep 27, 2024 at 5:03 pm PT
MOUNT DIABLO, CA — During a recent mountain bike ride at Lime Ridge, a former Save Mount Diablo employee saw a group of "rather large birds" circling above.
"I kept on riding, not looking too much into it because why would I think they could be condors?" Frenchy Hendryx said. "The next day, I heard the story that condors had flown over the area from Sean [Burke], and at that point, I wanted to know what time they had flown over. When the times matched, I got excited. I may have seen condors! I will definitely be looking out for them now and paying closer attention. A condo of condors is just not something you see every day in the Mount Diablo area."
It was confirmed that on Aug. 18, seven critically endangered California Condors flew north into Alameda and Contra Costa counties on a circuitous aerial tour, the Walnut Creek-based nonprofit organization Save Mount Diablo announced Monday.
The condors took a three-hour flight, departing at noon from their overnight roost site south of Ohlone Regional Wilderness. They soared over Pleasanton and Sunol, near the intersection of Highways 580 and 680 — the furthest west the birds have flown in the East Bay.
After flying over Dublin and Tassajara, the birds ventured north over Mount Diablo’s Pine Canyon near Castle Rock—a possible future nesting site and where Save Mount Diablo previously helped reestablish endangered peregrine falcons—and as far north as Lime Ridge Open Space west of Clayton before veering east—the furthest north the birds have flown in Contra Costa County.
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The birds circled Mount Diablo before heading south over the outskirts of Livermore and then spending the night in the mountains near Lake Del Valle. The condors, fitted with radio and GPS transmitters, did not appear to have landed during their time in the area.
How does Save Mount Diablo know all of this? Wildlife biologist Joseph Belli, a volunteer for the California condor recovery program at Pinnacles National Park, also works closely with Save Mount Diablo and pays special attention to birds ranging up and down the Diablo Range.
The condors' flight paths are tracked via GPS and highlight the vital role the Diablo Range plays as a wildlife corridor.
Save Mount Diablo, which recently expanded its geographic scope to 12 counties, has been instrumental in supporting these efforts, funding GPS transmitters and data subscriptions that allow for detailed tracking of the condors’ movements.
"We would rarely know of these long-range flights if it weren't for the GPS transmitters on some of the condors," said Alacia Welch, the Condor Program Manager at Pinnacles National Park."I've been monitoring condors for nearly 20 years and it's wonderful to see groups of them exploring further north in the Diablo Range every summer for the past four years. I wouldn't be surprised if these summer forays continue into the future, so all you eagle-eyed condor enthusiasts should keep an eye to the sky!"
If the Aug. 18 flight sounds familiar, it’s because a very similar event occurred around this time last year when six condors undertook an exploratory flight near Mount Diablo. It was the first flock in Contra Costa County in 100 years. Two of them—No. 1021, a 3-year-old male, and No. 943, a 6-year-old male—were also among this year's group. California Condor No. 943 made news in June 2022 for making a solo flight near Brushy Peak, the second condor documented in the area in over a century after Condor No. 828’s ground-breaking journey in August 2021.
The other five—Nos. 1099, 827, 912, 986 and 1078—were a mixture of juveniles and young adults, both male (Nos. 827, 912 and 986) and female (Nos. 1099 and 1078). The younger age group tends to undertake ambitious discovery flights, while older condors with nesting territories tend not to wander as extensively. Condors can begin breeding as early as 5 years old but generally wait until they’re at least 6 and often much older before nesting. No. 827 was the oldest of the group, an 8-year-old male who has not yet found a mate.
The group is also a blend of condors raised in captivity—Nos. 1099, 827, 986, and 943—and products of wild nests—No. 1021 from southern San Benito County and Nos. 1078 and 912 from Pinnacles National Park. Pinnacles and Ventana Wildlife Society co-manage the flock, managing release sites and monitoring the birds from the park and Big Sur.
Because there are so few condors, each one has a radio transmitter and is essential to the overall population. This allows the birds to be tracked if necessary.
Less than half the flock also wear GPS transmitters, though most Pinnacles birds do thanks, in part, to Save Mount Diablo. In the last few years, the organization has funded additional GPS transmitters and subscription services for Pinnacles birds with grants from its Mary Bowerman Science and Research Program. The transmitters and subscription services allow precise flight tracks to be monitored and recorded.
Condors prefer to fly over undeveloped areas. The theory in making the grants for GPS transmitters and subscriptions, especially for young birds, was that their GPS flight tracks would define and highlight the importance of the giant Diablo Range as habitat for the birds—200 miles north-south and 3.5 million acres of high-quality intact habitat. The theory is proving to be true.
According to the American Bird Conservancy, California condors are considered critically endangered. Their current population is around 504, and it is trending upward.
The central California flock consists of roughly 100 free-flying condors, ranging from north of Paso Robles and San Luis Obispo to southern Santa Clara County and occasionally beyond.
That number will increase toward the end of the year when 10 to 12 young condors raised in captivity will be released.
It’s also been a banner year for nesting, with a record nine chicks potentially ready to fledge in fall. The growing population bodes well for the future and the likelihood of more frequent condor appearances in the East Bay.
As Save Mount Diablo continues to expand its efforts across the Diablo Range, its focus remains on ensuring that wildlife connectivity persists for future generations. The nonprofit group believes protecting these lands is crucial to the survival of California's most iconic species.
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