For more than two months, starlings have been flocking to Ireland's County Cork in increasing numbers — and so have the birdwatchers hoping to catch a glimpse.
Those observers caught a showstopper of a performance earlier this month.
In a video recorded and posted to Facebook by Birdwatch Ireland's West Cork branch, a flock of starlings — also known by the considerably cooler term murmuration — swoop and dive in movements so choreographed, they take on the likeness of a single, slinky organism in the twilit sky.
Of course, the birds number far more than that.
"I estimate there are between 5,000 and 10,000 starlings, which would make it the biggest murmuration we've had in West Cork," Peter Wolstenholme, a member of the birdwatching group and the man behind the camera, told Ireland's Independent newspaper.
So, what caused such a crowd to break into synchronized acrobatics?
If you squint, you can catch a single black figure following its own path, arcing above the group about 17 seconds into the video and making headlong stabs at the flock at various points afterward. That's a peregrine falcon, hunting for its evening meal.
In a study cited last year on NPR by anthropologist Barbara King, researchers noted that starlings manage to bob and weave together with a relatively minimal amount of effort — and without any one bird leading the way. The study concluded that by simply interacting with six or seven neighbors, and largely disregarding the thousands of others in its flock, each starling makes its movements efficient and plays a part in crafting a cohesive group.
The result is tight-knit, unpredictable — and deeply confusing for the peregrine falcon. Wolstenholme told the Irish Times he has been watching the murmuration from the village of Timoleague nearly every day for weeks, and he still has seen only one predator have any success.
"When it first started there was a sparrow hawk there, and he tried to attack the murmuration and got nowhere. But very cleverly, he realised that if he went and sat in the wood where they all roost, he could just grab one," Wolstenholme said. "And he came flying past me against the sunset with a starling in his talons."
This dance may be a headache for hawks and falcons, but for bird-watchers it made for a gorgeous regular spectacle. And it's far from the only one. For weeks, Birdwatch Ireland has been posting footage of the birds above Timoleague, including this scene Monday.