Solitary sandpipers (Tringa solitaria) probe the mud and shallow water for aquatic invertebrates, bobbing their rears up and down. I spent some quality time with a solitary sandpiper on May 4, 2021, north of Gapstow Bridge at the Pond in Central Park. I find their white eyerings very distinctive.
Solitary sandpipers visited Central Park in 2017 after a lot of rain, seeking really good bugs along the puddles of water that collected near the compost heap south of Conservatory Garden. They were there for two or three days; I got to see them on April 27, 2017. These birds do not travel in large flocks, but we did see three or four that day. They did not interact much with each other. We saw one approach another solitary, who immediately sent the visitor flying.
The Filming the Feathers video features the birds seen on April 27, set to flute compositions by Handel and Saint-Saens, performed by Paula Robison and Martha Goldstein.
All these photos are from April 27.