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.
