Turkey Vulture and Swainson's Hawk Migration
As noted by Tom Miko and Luke Tiller on the LA County listserve, there was a significant push of turkey vultures and Swainson's hawks along the San Gabriel Mountain foothills on February 28. I was also counting from northern Altadena shortly before and after Luke and tallied 90 vultures from 10:20-11:00, 130 from 11:40-11:50, and another 20 at NASA-JPL at 12:25. Several other ebird reports from Feb. 28 tallied dozens of vultures; there were also reports of good numbers from Feb. 26 and 27. If you look in eBird, you can see that turkey vulture migration in LA County has two annual peaks corresponding to spring and fall migration. The spring peak occurs from late February into about the second week of March. The fall peak occurs from early to mid October. In 2022, about 3400 turkey vultures were reported in eBird in the first two weeks of March and about 2500 were reported in the first two weeks of October.
Luke's report of 70+ Swainson's hawks is a reminder that migration by this species is picking up. Last year Los Angeles Birders organized an informal survey to monitor the numbers and investigate the migration routes through the county by this species. We hope to make this an annual event, so this year we're doing it again, and encourage everyone to report Swainson's hawks in eBird whenever you find them. In 2022 most of them were reported from Claremont to Pasadena to Tujunga and Bear Divide (i.e., along the south flank of the San Gabriel Mountains), but the extent to which they pass through the Antelope Valley and San Gabriel Mountains wasn't covered thoroughly. In 2023 we plan to check that in more detail by establishing a north-south "picket line" from the San Gabriel Valley into the San Gabriel Mountains and extending into the Antelope Valley on one or two days.
The peak in Swainson's hawk migration in Los Angeles County usually occurs in the middle of March +- one week, so we hope to set up the picket line in about two weeks. However, this is partly dependent on road conditions: currently many of the roads in the San Gabriel Mountains are closed due to snow, so we need be flexible with our plans. Tentatively, and conditions permitting, we hope to try the picket line during the week of March 12-17. Stay tuned for more details about this as our plans solidify.
We also hope to get as many reports as possible on the weekends of March 4-5, 11-12, and 18-19 from across the county. If you see large groups of Swainson's hawks, please report them on the LA County listserve and on eBird as soon as possible. For folks who like to use WhatsApp, please note that that many other birders _don't_ use it, so if there are report on WhatsApp please cross post them to the county listserve.
Our plans are still coming together with this so we'll post more about this on the county listserve and on the Los Angeles Birders website soon.
On behalf of Los Angeles Birders