Date: 4/19/26 11:10 am From: Barry Langdon-Lassagne via groups.io <wilmot...> Subject: Re: [slocobirding] Birds on the Moon
Bill,
Your post reminded me of an article I read that was written in 1952—back then of course there was no BirdCast, so scientists had to rely on the technique you describe, watching birds cross the full Moon during migration, for estimating the size of migrating flocks!
“The procedure is simple. The full moon is watched through a telescope by an
observer who notes the passage of birds crossing the face of the moon. A second
person records the time and direction of flight.”
—Charles Sibley, the Bulletin of the Santa Clara Valley Audubon Society, July-August 1952
Such a cool and ingenious way to get scientific data. And I’m so glad we have BirdCast now!
Barry Langdon-Lassagne
~
> On Apr 18, 2026, at 11:32 AM, ChicoBill via groups.io <w.e.haas2...> wrote:
>
> Some of you may already be attuned to this; however, the recent high-intensity bird migration alert for the night of 17 Apr 2026 suggested this opportunity to share another of the many wonders of the Cornell Ornithology Lab (whose former director was my college roommate - who endlessly lectured me about the beauty of Empidonax flycatchers - and who was instrumental in bringing to fruition many of the lab's technologically advanced projects including one that may also be familiar to some of you, eBird - OK, most of you). This one - BirdCast:
>
> (https://birdcast.org/migration-tools/)
>
> One can subscribe to BirdCast alerts to discover and to explore patterns of nocturnal bird migration in the contiguous United States - I use it to study West Coast bat migrations, which it is equally good at deciphering. During migration events, especially high-intensity events, one can typically hear flight calls of migrating birds, especially from along shorelines, riparian corridors, and ridgelines. However, viewing is typically difficult. On that note, in the coming weeks, the Central Coast will experience two full moons: the Flower Moon on Friday, May 1 and a Blue Moon on Sunday, May 31. When conditions are right - that is, with the combination of a full moon AND a major nocturnal migration - it is possible to see silhouettes of migrants as they pass between us and our favorite cheesy satellite. Often, a scope or bins are not necessary.
> --
> Bill Haas
> Paso Robles
>
