Bird of the Month: Stilt Sandpiper
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
The Stilt Sandpiper blends the appearance of a yellowlegs with the behavior of a dowitcher. So much so that some hunters in the 19th Century referred to it as the Bastard Yellowlegs.
Its long, thin legs give the Stilt Sandpiper the appearance of a yellowlegs, but its legs have a more greenish hue. Its bill is decurved at the tip and contrasts with the short, straight bill of the Lesser Yellowlegs (Tringa flavipes) and the upturned bill of the Greater Yellowlegs (T. nelanoleuca). In flight the wings are plain with only a faint white stripe and appear dark at a distance. Hunters in the 19th Century referred to the Stilt as the Bastard Yellowlegs because they thought it was intermediate between the two (Klina and Jehl). However, it is smaller than both yellowlegs.
The Stilt differs considerably from the yellowlegs in its feeding pattern which resembles the “sewing machine” probing used by dowitchers. It is comfortable wading in water up to its breast as it forages rapidly often submerging its head in the process. Photos, video, and vocalizations of the Stilt Sandpiper can be reviewed at the Macaulay Library.
Stilt Sandpiper
Scientific Name: Calidris himantopus
Length: 8.5”
Wingspan: 18”
Weight: 2oz (58 g)
AOU Alpha Code: STSA
CENTRAL FLYWAY MIGRANT
Stilt Sandpiper breeds in the North American arctic tundra and winters over a wide range in central South America. In spring, these long-distance migrants fly non-stop across Central American and the Gulf of Mexico and then may make several stops on the way north through the central United States and Canada arriving on the breeding grounds in late May. The Stilts have a high rate of breeding site fidelity and as many as 50% of the pairs in a location may be returning there to breed in consecutive years.
Fall migration is protracted with females beginning to fly south in mid-July and males following soon after. Juveniles migrate between late July and early September. The Stilt is rare in Western Washington in spring and uncommon in some locations in August. The Stilt Sandpiper tends to avoid tidal flats and prefers standing water in pools and lagoons where it forages for flying insects, diving beetle larvae, midges, and other aquatic invertebrates. (Klima and Jehl).
AN ARCTIC NESTER
On the breeding grounds the male Stilt Sandpiper preforms a dramatic courtship flight in which it pursues the female in the air, gets in front of it, and then raises its wings in a deep “V” shape over its back, singing while it plummets to the ground (Kaufman). This flight can alternate with a low-altitude flight of shallow wingbeats as the male circles the female.
Prior to nesting, the male makes several scrapes in the tundra, usually on a raised hummock or dry area surrounded by water. The female chooses one of them and deposits four eggs directly on the ground. Both parents share incubation duties for about three weeks with the female taking the night shift and the male incubating during the day. The young leave the nest soon after hatching and find all their own food. It takes the young a little over two weeks to fly and they migrate on their own (Kaufman).
POPULATION AND CONSERVATION
The Stilt Sandpiper is a relatively rare species of shorebird with a population somewhere between 50,000 and 100,000 individuals. Numbers vary considerably because identification can be problematic as these birds can be confused with other species. Studies in three breeding regions have revealed that fewer birds are breeding near Hudson Bay, possibly due to overgrazing by Canada and Snow Geese which opens the habitat making it more accessible for predators. However, populations in Alberta, Canada and Prudhoe Bay, Alaska are increasing, suggesting a westward shift in the breeding habitat (Klina and Jehl). There are no management plans in place for Stilt Sandpiper.
Stilt Sandpiper is placed in the genus Calidris, from the Greek kalidris, used by Aristotle to denote a speckled waterbird. Twenty-four shorebirds in this diverse genus have been recorded in North America. The species epithet himantopus, is from the Latin himantos, for strap or thong, and pous, for foot. It relates to this bird’s long, thin legs, which are thought to be similar to a leather thong (Jobling).
Photo credit by Andrew Weitzel and Dan Pancamo. References available upon request from amccormick@eastsideaudubon.org.