ON MAY 11, 2018, ANDREW FARNSWORTH saw something that was almost unbelievable. A migration ecologist at the Cornell Lab of Ornithology, Farnsworth has seen more than his fair share of rare birds. But there was one species native to the Lower 48 that he’d never recorded—a Kirtland’s Warbler—and he assumed doing so would require a trip to its breeding grounds in Michigan’s jack pine forests. The rare warbler is all but unheard of in New York State. That a Kirtland’s came practically to his front door when it stopped over in Central Park, not far from Farnsworth’s Manhattan apartment, was nothing short of extraordinary. “I think it was reported about 5 p.m.,” he says. “I took a cab to 60th and Fifth, bailed out, and then ran. Fast.”
After spotting the bird, Farnsworth realized the warbler was only part of the spectacle. “Seeing the speed with which tens and then hundreds of people appeared in the park to see the bird was like a BTS concert or a Beatles concert,” he says. A birder named Kevin Topping first spotted the Kirtland’s and posted about it on Twitter, where it was immediately picked up by Manhattan Bird Alert—a feed that reposts sightings of birds in the park, particularly uncommon species. The news got out through more traditional means, but none are geared toward speed quite like Manhattan Bird Alert. By 6:30 p.m. hundreds of people were watching the bird; the crowd was so large and had formed so quickly that the cops came. To Farnsworth, who has birded in Central Park for decades, it was clear that something had shifted: “That was a moment of like, wow, this is a whole different level. The whole social media angle to alerting people has arrived in a very different, sort of explosive way.”
Social media has become a powerful tool for broadcasting the appearance of rare or otherwise remarkable birds and made it far easier to chase sought-after species. Last October, for example, Twitter (now called X) lit up with alerts of the Lower 48’s first recorded Willow Warbler, native to northern Eurasia, and hundreds of birders made their way to a lagoon in California’s Marin County to catch a glimpse. Similar frenzies have swept across the Midwest as Limpkins, tropical waders rarely seen north of Florida, have popped up in ponds and marshes as far north as Minnesota in recent years. And a Steller’s Sea-Eagle—native to far-eastern Russia and parts of Asia—that’s been crisscrossing North America for three
