The southward migration of the swifts from all over the Northwest usually starts in September, affording us more opportunities to view thousands of them entering the chimney. The success was greater that possibly imagined.  One Sunday night in early September last year saw 25000 birds enter the chimney before dark.  Similar counts happen each night during the 3-4 weeks of migration.  You can watch them and meet our volunteers from the corner of W D St and W 3rd St near Fox Creek in Rainier, Ore.

More here: https://willapahillsaudubon.org/news/674-2024-vauxs-swifts-fall-migration-is-in-full-swing