Oddpipers
Something is wrong with this picture! The birds look like Least Sandpipers: small, brownish back, slight white eyebrow, medium black beak slightly curved downward, yellowish legs. But the behavior is unlike any Least Sandpiper described in the literature. Least Sandpipers forage on broad mudflats or sparse gravelly beaches, generally within 1 meter of water’s edge. They have not been described as foraging on rocks at the water’s edge, so close that their beaks dip into the water to get at things in the seaweed just below the surface. Their foraging behavior resembles turnstones and surfbirds more than sandpipers.
I saw the same birds with the same odd behavior here in January this year (“Rockpipers?” Jan 22 2022) and a month earlier (“Stones and Pipers,” Dec 18 2021). In the December post I considered and dismissed the possibility that these were really Rock Sandpipers (Calidris ptilocnemis). They don’t look similar. But there is a bird that looks so similar to the Least Sandpiper that experts have to work hard to tell them apart. That would be the Long-toed Stint (Calidris subminuta). This is primarily a bird of Asia. It very occasionally occurs in Alaska. When expert birders spotted one in Monterey CA in 1988, it made ornithological headlines. Little is known about its diet and foraging, but the subscription service Birds of the World has this teaser: “Usually feeds among vegetation at water’s edge.” That would be this bird.
It’s tempting to propose that Chavez Park has been visited by this rare-here species. But it’s more likely that we’re simply seeing a foraging adaptation in the common Least Sandpiper. These birds simply have a broader range and more versatile feeding talents than has previously been documented. In some future updated description of Least Sandpiper behavior you will probably read that they also forage on rocks covered with vegetation at the water’s edge.
