While we slept, three-quarters of a million migrating birds flew over King County in one night this week.
Why it matters: Fall migration is ramping up, sending huge numbers of birds south under the cover of darkness, according to Cornell Lab of Ornithology’s BirdCast migration tracker.
By the numbers: BirdCast estimates 751,700 birds crossed King County Thursday, with traffic peaking around 12:50am when about 279,000 birds were simultaneously in flight.
- Across Washington, more than 3.6 million birds migrated overnight, traveling southeast at an average 25 mph, 3,700 feet above the ground.
- BirdCast says migration generally begins 30–45 minutes after sunset, with the greatest number of birds aloft two to three hours later.
Stunning stat: On Sept. 1, just 1,700 birds were estimated to have crossed the county. Two days later, that number jumped to almost 420,000…