During fall migration, flocks of more than 200 000 semipalmated sandpipers can be seen in the Bay of Fundy. They are quite a sight when flying as they are synchronous and look much like an aerial school of fish.
The semipalmated sandpiper is the second smallest of the ‘peep’ sandpipers, a group of small shorebirds that are very hard to distinguish from each other. It measures only 14-16 cm in length, the size of a house sparrow. Like many sandpipers, the semipalmated sandpiper’s breeding plumage is simply a slightly darker version of its winter colouration. Breeding adults have black legs, dark brown, streaked and mottled upper parts and pale or white underparts. The breast is lightly marked with pale brown. The semipalmated sandpiper can be distinguished from the least sandpiper by its bill, which is shorter and stouter.
Semipalmated sandpipers breed across Canada, from the treeline to the southern Arctic islands as well as along the coast of Labrador. They winter from South Carolina south to Chile and Brazil, passing through the Maritimes during their fall migrations.
Each spring, male semipalmated sandpipers arrive at the breeding grounds before females in order to establish territories. A male often defends the same patch year after year, on moist tundra or sandy areas near water. Males and females couple and then spend several days scraping out their nest, which they line with grass and willow leaves. The eggs are incubated for 18-19 days, with both parents sharing incubating duties. Like all sandpipers, the young of this species are precocial- downy and able to run within hours of hatching. Juvenile sandpipers are abandoned as early as 10 days of age, left to migrate southward on their own several weeks after the adults. The semipalmated sandpiper is very common in southern Canada during its migratory stopovers on beaches and shorelines.
During the breeding season, the semipalmated sandpiper eats insects and aquatic invertebrates. On migration, it consumes primarily aquatic insects, worms, crustaceans, and small molluscs. The semipalmated sandpiper is an active feeder, running along the water's edge with its head down, searching for prey.