Baby-faced Black-bellied Plovers in New York Harbor

A juvenile Black-bellied Plover recently caught a young clam worm in its beak along Sandy Hook Bay, NJ. 

Written by Joe Reynolds
New York Harbor Nature Blog

Shorebird migration is not over yet. Birds are still in flight to select a worthy coastal home to spend the winter, perhaps even deciding to stay around New York Harbor.
 
Over the weekend, I spotted a small flock of about 20 or so juvenile black-bellied plovers (Pluvialis squatarola) stopping to rest, relax, and feed before either continuing their winged migration southward or maybe spending the winter around the Hudson-Raritan estuary. The winter range for this plover is extensive, from New England and Nova Scotia to southern South America and everywhere in-between. The birds prefer to winter on coastal ocean beaches or along the shoreline of estuaries where they can easily forage for small polychaete worms, bivalves, and crustaceans.
 
I first spotted this young group of black-bellied plovers on Friday. They were foraging for small worms during low tide at Horseshoe Cove along Sandy Hook Bay. The next day, the shorebirds were observed a little farther south, resting on a sandbar during high tide in Spermaceti Cove, still located in Sandy Hook Bay.

​The birds were relatively easy to recognize. At nearly 12 inches long, black-bellied plovers are the largest of our plovers. They are much larger than their more famous cousin, the piping plover, which measures in at about 7 inches in height. Although black-bellied plovers look similar to American golden plovers, especially in nonbreeding plumage, there are some important differences. According to the Sibley Field Guide to Birds, non-breeding or juvenile black-bellied plovers have a black “armpit,” white belly and white wing-stripes, as opposed to the American golden plover.
 
The birds I observed in Sandy Hook Bay all appeared to be juveniles, with an additional streaked breast and pale cap. While black-bellied plovers can often be seen migrating from late July to early December, the adults or nonbreeding birds are usually the first to start fall migration, with juveniles appearing mainly from late September on.
 
The birds nest on dry ground in the high tundra, often above lowland lakes and rivers. Once the eggs are hatched, the adults will migrate soon after to escape the cold winds of a brief breeding season up in the Arctic. Within hours of hatching, young shorebirds are walking around, foraging for food and usually able to fend for themselves. 

​For many shorebirds species that nest in the Arctic, the adults depart first, and the young birds will set out later by themselves. There is often a full month or more between the peak passage of adults and the peak passage of juveniles.
 
The question is, with no adults to guide or supervise them, how do young black-bellied plovers know where to go to wintering grounds they have never been to before?

​Did the flock of juvenile black-bellied plovers I observed last weekend get lost during their long southbound migration, or maybe Sandy Hook Bay is somehow encoded in their brains as an important migratory stopover site. Only time will tell. No doubt, though, migration can be an exciting time. It’s best to always keep binoculars and a field guide handy when spotting a flock of unexpected shorebirds around New York Harbor.