Ruddy Turnstone

Overview

The ruddy turnstone (Arenaria interpres) is a stocky, energetic shorebird built for methodical beach work. In breeding plumage it is striking — chestnut and black upperparts, white underparts, a bold black-and-white head pattern — but on the Tortuguero beach it appears in non-breeding plumage: duller, brownish-gray above, retaining the white underparts and the distinctive orange-red legs. Adults measure 21–26 cm. The short, wedge-shaped bill, slightly upturned at the tip, is the tool that gives the species its name: it flips stones, shells, and seaweed to expose invertebrates beneath.

The species is one of the champion long-distance migrants on earth, breeding in high-arctic and subarctic tundra across Eurasia and North America and wintering on coasts at almost every latitude. Genetic studies show that Caribbean-wintering birds originate primarily from Canadian arctic breeding populations.

Why Tortuguero

Tortuguero’s long, open Caribbean beach provides precisely the habitat turnstones seek: a wave-washed tideline, accumulations of wrack (kelp, Sargassum, and debris) that concentrate amphipods, isopods, and small crabs, and the exposed sand flats near the river mouth. While the beach is famous as sea-turtle nesting habitat, it also serves as an important wintering and stopover ground for multiple shorebird species. The ruddy turnstone is the most reliably encountered shorebird on the Tortuguero beach, present in small to moderate flocks most mornings from August through March.

How to see them (honestly)

• When: August through March; peak numbers in September–October (southbound migration) and December–February (wintering). Absent or very rare May–July.
• Where: the open beach outside the village, particularly near the river mouth and in areas with wrack lines. Early-morning boat trips that exit the canal onto the beach face can pick them up quickly.
• What to watch: active, jaunty birds flipping debris with bill and occasionally turning small stones with a quick body twist. They move in small groups of 3–15, often mixing with other shorebirds (sanderlings, semipalmated sandpipers).
• Non-breeding ID: brownish gray above, white below, orange legs, short upturned bill. The white throat patch and partial head pattern are visible even in dull plumage.

Status note

Globally Least Concern with large worldwide population. However, several long-term shorebird monitoring programs show declines in some populations, linked to habitat degradation on breeding grounds (climate-driven tundra changes) and on key stopover sites. The IUCN notes the global population trend as decreasing. For Costa Rica, the species remains a common non-breeding visitor with no local-level threat.