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Black Turnstone Life History

Habitat

Habitat Shorelines

For most of the year, during the nonbreeding season (August through April), Black Turnstones live along Pacific coastlines, especially rocky habitats with strong surf. Jetties and piers also provide habitat for them. Most of their foraging and roosting is on rocks, but they also sometimes feed in adjacent muddy or sandy environments. For breeding, Black Turnstones use arctic coastal lowlands dominated by sedges and beach rye and dotted with small ponds. Some also nest in drier, higher-elevation zones farther from the coast, where sedge meadows include more willows and sphagnum mosses, or on gravel bars in streams, beneath willows. After the breeding season, Black Turnstones gather along gravel shorelines of lakes and rivers and also in coastal mudflats, especially where there are stony habitats for roosting and foraging.

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Food

Food Aquatic invertebrates

Black Turnstones are named for the main way they forage: using their short, chisel-like bill to flip over objects on beaches. They also use the sharp bill to hammer or pry open shellfish. They walk along jerkily, flipping over stones, shells, seaweed, driftwood, and other flotsam. Where seaweed is heavy, they sometimes “snowplow” with their whole body into a mass of beach wrack to uncover prey. The food they discover in this manner includes adult and larval flies, beetles, spiders, fish eggs, sea spiders, bristleworms (polychaetes), and small crustaceans (amphipods, isopods), among others. When feeding on shellfish and other hard-shelled invertebrates, such as mussels, limpets, snails, or barnacles, Black Turnstones use their bills to pry the animals loose from the rocks and to stab into the shell to consume the flesh. Like many shorebirds, they take advantage of local abundances of prey on sandy beaches, sometimes racing back and forth with the waves, pulling small crustaceans from the wet sand, then hammering them before consuming. Shore flies (brine flies) and their tiny larvae form a large portion of the diet during the nesting season, but they eat almost anything during the short breeding season: eggs of other tundra-nesting birds, seeds, berries, and a great variety of insects and marine organisms. In areas where fish such as salmon have spawned and died, they consume carrion, fly larvae, and fish eggs. These turnstones sometimes ram into bunches of sedge with the head in order to expose or flush small insects concealed there.

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Nesting

Nest Placement

Nest Ground

Males make scrape nests among sedges, usually on small islands in brackish ponds not far from the shore but sometimes on river islands, where nests may be set beneath willows.

Nest Description

Nests consist of bowl-shaped scrapes formed in sedges, lined by both sexes with bits of nearby vegetation such as sedges, beach rye, willow, or grasses and hidden beneath overhanging grass or sedge stalks. The interior nest cup averages about 3.9 inches across and 1.7 inches deep.

Nesting Facts

Egg Description:

Olive with pale brownish speckling.

Condition at Hatching:

Active and covered with down.

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Behavior

Behavior Ground Forager

Soon after arrival on the breeding grounds, male Black Turnstones begin displaying over breeding territories in sedge meadows, often chasing rival males in flight. Even before pairing with a female, males fly in circles about 50 feet above the territory, slowing to a level, forward flight on rapidly fluttering wings, then dropping to earth with raised wings or in zig-zag flight. Vocalizations accompany each part of this display flight, which may last up to 5 minutes. When turnstones pair, they fly together in a courtship flight, with the male trailing the female closely as she surveys the territory. On the tundra, male and female display to one another with raised tails and lowered breast. Males sometimes also raise their wings high. Males hover near females in a “helicopter” hover, with head raised and legs dangling, and make motions as if scraping out a nest site with the feet and molding it with the breast. Males also puff out the body and give cricketlike calls. Black Turnstones are monogamous, and both parents share incubation and chick-rearing duties. Pairs often reunite in successive breeding seasons.

After the young have fledged in midsummer, Black Turnstones move to outer coastlines and river shores to form flocks, then migrate southward toward wintering areas. They begin to move northward again in April. During the nonbreeding season, Black Turnstones are social, roosting and feeding in groups. Each bird defends a small feeding area against intrusion by flockmates. Conflicts can be fun to watch, as rivals square off, bill to bill, chattering and posturing to preserve their patch of rock.

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Conservation

Conservation Restricted Range

Black Turnstones are fairly common along Pacific shorelines in the nonbreeding season, but they breed in the remote arctic where it's hard to monitor their population trends. Partners in Flight estimates a global population of 95,000 breeding birds, rates the species a 15 out of 20 on the Continental Concern Score, and includes it on the Yellow Watch List for birds with restricted ranges. Studies in the Pacific Northwest suggest that populations in wintering areas there have been declining. As with other shorebirds, Black Turnstones are vulnerable to oil spills. The Exxon Valdez spill in 1989 oiled or poisoned Black Turnstones, led to lower reproduction, and contaminated their coastline habitat with crude oil for years following the wreck. Black Turnstones ingest both small plastic particles and lead shot, which are similar in size and shape to their food.

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Credits

Handel, Colleen M. and Robert E. Gill. (2001). Black Turnstone (Arenaria melanocephala), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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