Sleepy Shorebirds
They fly, they feed, they sleep, and they fly again. These little birds (5-8 inches), plovers and sandpipers, are long distance migrators – up to 4000 kilometers. During their long journey’s pursuit some species touch down in Casco Bay to feast on marine invertebrates – restoring their energy stores. They are easy to miss, but during September the Semipalmated Sandpiper (SESA), the Least Sandpiper (LESA), the Semipalmated Plover (SEPL), and the Spotted Sandpiper are seen on the shores of Vaile Island, Wharf Cove and East Ryefield Cove.
The Spotted Sandpiper stands out alone from the other three shorebirds mentioned here. It is slightly larger and generally feeds alone. Sometimes it washes its food before swallowing. The others swallow their food immediately. And, this sandpiper prefers more than one mate whereas the SESA, LESA and the SEPL favor one mate. It bobs its tail.
However, all share some similar traits. They breed in northern North America. Nests are built with available plant material in a small depression on the ground. They generally have 4 eggs that are incubated for up to 3 weeks and the chicks fledge at 2-3 weeks. In migration, the female generally departs first followed by the male (late June and July). The juvenile birds migrate south during August to early October, much later than the parents. No parental training or maps are provided but they find their compass. Humbling – we need GPS to get across town.
Apparently the shorebirds in these photos are juveniles – spending time here in September. Adults perhaps are further south of here.
Upon arrival they feed and sleep in small groups (except the loner Spotted Sandpiper), perfectly camouflaged in the sand, rocks, and seaweed.
However great their camouflage is, they are always on the look out for predators lurking in the sky or on land.
The Semipalmated and Least Sandpipers probe or peck for their favorite foods along the shoreline and especially in weed wracks that accumulate near the high tide mark: amphipods, tiny mollusks, insect larvae (especially those ones found in seaweed mats), and worms. The Semipalmated Plover feeds primarily on polychaete (segmented) worms, small mollusks, crustaceans and insects. Using downward pecking movements along water margins the Spotted Sandpiper feeds on aquatic and terrestrial insects.
Simple characteristics that you can use to distinguish these four shorebirds from each other:
The small Semipalmated Sandpipers with their grey-black legs are easy to distinguish from
the Least Sandpipers with yellow-green legs.
The Semipalmated Plover is somewhat larger, displays a ring around its neck and has a broad dark head. The juvenile plover has a lighter brown head and back.
The Spotted Sandpiper sports a spotted breast during breeding season, but not now, there are no a. It has bright yellow legs and bobs its tail year round. Why does it bob its tail, and others do not?
Breeding and winter grounds:
Even though all 4 shorebird species breed in northern North America and move southward in the winter, each prefers specific parts of North, Central and South America.
Semipalmated Sandpiper (Calidris pusilla)
Breeds from western and northern Alaska, and eastward through northern Canada.
Fall migration: Migrates up to 4000 km to the West Indies and northern to central South American coasts.
Least Sandpiper(Calidris minutilla)
Breeds throughout Alaska, northern Canada and into Quebec and Newfoundland/Nova Scotia.
Fall migration: They move in a broad front over interior of North America to southern US, Central America, West Indies, and the upper half of South America.
Semipalmated Plover (Charadrius semipalmatus)
Breeds throughout Alaska, northern Canada and into Quebec and Newfoundland/Nova Scotia.
Fall migration: Both coasts of southern US, West Indies, Galapagos Islands, and both coasts of South America (excluding the southern most tip).
Spotted Sandpiper (Actitis macularia)
Breeds from throughout Alaska and across middle and southern Canada to Newfoundland and upper US.
Fall migration: Moves in broad fronts across North America into southern US, Mexico, Central America and the upper ¾ of South America.
Reference:
del Hoyo, J., A. Elliott, and J. Sargatal. 1996. Handbook of the Birds of the World. Vol. 3. Lynx Edicions. Baracelona.
Written and photos by: Patty Wainright
Least Sandpiper photo by: Birdpixels.com
Reviewers: Michelle Brown, Michael LaCombe, Marty, Sam Wainright
