Turnstone
Stocky waders that overturn stones for invertebrate prey.
Wikipedia / Wikimedia Commons
The genus *Arenaria*, part of the wader family Scolopacidae, contains just two species: the ruddy turnstone and the black turnstone. These birds are close relatives of the calidrid sandpipers and may fall within the tribe Calidriini. French zoologist Mathurin Jacques Brisson first described the genus in 1760, naming the ruddy turnstone as the type species. The name *Arenaria* comes from the Latin *arenarius*, meaning "inhabiting sand," itself derived from *arena* ("sand").
Both turnstones are waders, stocky for their group, with short, slightly upturned, wedge-shaped bills. They measure 20 to 25 cm in length, have a wingspan of 50 to 60 cm, and weigh between 110 and 130 g. White patches mark their backs, wings, and tails. They breed in the high Arctic and migrate seasonally. Their strong necks and powerful, upturned bills are adapted for flipping over stones, seaweed, and other debris to find invertebrate prey. Strictly coastal birds, they prefer stony beaches over sandy ones and often share these habitats with other waders like purple sandpipers.
A fossil bone—a distal piece of tarsometatarsus from the mid-Blancan period (roughly 4 to 3 million years ago)—was found in the Edson Beds of Sherman County, Kansas. It appears to belong to a calidriid similar to the pectoral sandpiper but shows some traits reminiscent of turnstones. Depending on which features are ancestral or derived, it may represent an early member of either lineage.
- genus
- Arenaria
- family
- Scolopacidae
- species
- ruddy turnstone (Arenaria interpres) and black turnstone (Arenaria melanocephala)
- length
- 20–25 cm
- wingspan
- 50–60 cm
- body mass
- 110–130 g
- habitat
- high Arctic breeders, migratory, strictly coastal, prefer stony beaches
Lore & Background
Turnstones are waders with a stocky build, short slightly upturned wedge-shaped bills, and white patches on the back, wings, and tail. They are high Arctic breeders and migratory. Their strong necks and powerful, slightly upturned bills are adapted to their feeding technique: overturning stones, seaweed, and similar items in search of invertebrate prey. They are strictly coastal, preferring stony beaches to sand, and often share beach space with other waders such as purple sandpipers.
The genus contains two species: the ruddy turnstone (Arenaria interpres) and the black turnstone (Arenaria melanocephala). A fossil bone—a distal piece of tarsometatarsus found in the Edson Beds of Sherman County, Kansas, dating from the mid-Blancan some 4–3 million years ago—appears to be from a calidriid somewhat similar to a pectoral sandpiper, but has some traits reminiscent of turnstones. Depending on which traits are apomorphic and plesiomorphic, it may be an ancestral representative of either lineage.
Reader's Guide
Turnstones are notable for their specialized feeding behavior, which gives them their common name. As members of the genus Arenaria in the family Scolopacidae, they are closely related to calidrid sandpipers and may be considered part of the tribe Calidriini. Their adaptation to coastal stony beaches and their migratory habits make them a distinctive group among waders. The fossil record, though limited to a single bone from the mid-Blancan of Kansas, suggests a possible ancestral link to either turnstones or calidriids, but the uncertainty remains unresolved. Their significance lies in their ecological role as intertidal foragers and in the taxonomic questions they raise regarding the evolution of shorebirds. The genus was formally described by French zoologist Mathurin Jacques Brisson in 1760, with the ruddy turnstone as the type species. The Latin-derived genus name reflects their sandy habitat. Both species are high Arctic breeders and migrate to coastal areas worldwide, where they often associate with other waders like purple sandpipers.
Did You Know?
- The genus name arenaria is from Latin arenarius, 'inhabiting sand', from arena, 'sand'.
- Turnstones have strong necks and powerful, slightly upturned bills adapted to overturning stones and seaweed for invertebrate prey.
- A fossil bone from the Edson Beds of Sherman County, Kansas, dating from the mid-Blancan some 4–3 million years ago, may be an ancestral representative of either turnstones or calidriids.
- Turnstones are strictly coastal and prefer stony beaches to sand.
Frequently Asked Questions
What is a Turnstone?
A turnstone is a compact, stocky wading bird in the genus Arenaria, a member of the sandpiper family Scolopacidae. They are easily spotted by their short, wedge-shaped bills that curve slightly upward.
How do Turnstones feed?
True to their common name, turnstones flip over rocks and stones along the shoreline to uncover hidden invertebrates. This stone-turning foraging technique is their signature way of finding food.
How many Turnstone species exist?
The genus Arenaria holds exactly two species: the ruddy turnstone (Arenaria interpres) and the black turnstone (Arenaria melanocephala). Both sit close to the calidrid sandpipers within the tribe Calidriini.
How big is a Turnstone?
Adult turnstones range from about 20 to 25 centimeters in body length with a wingspan of 50 to 60 centimeters. Their mass typically falls in the 110-to-130-gram range.
Where do Turnstones live and what does their name mean?
Turnstones favor sandy and rocky coastal habitats, which is why the genus name Arenaria derives from the Latin word for 'sand.' They are most associated with arctic and subarctic shorelines but also travel to temperate coasts.
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