Calidris ferruginea (Pontoppidan, 1763)

Taxonomy and Basic Identification

The curlew sandpiper, scientifically named Calidris ferruginea (Pontoppidan, 1763), is a small wader.

Size and Morphometrics

It measures 18–23 cm (7–9 in) in length, weighs 44–117 g (1.6–4.1 oz), has a wingspan of 38–46 cm (15–18 in), a bill length of 32–44 mm (1.3–1.7 in), and a tarsus length of 26–34 mm (1.0–1.3 in).

Bare Part Features

It has a black bill, dark brown irises, and dark grey to black toes and tarsi.

Rump and In-Flight Markings

All plumages have a large white patch on the rump, which is occasionally barred with red in some adults. In flight, it shows a distinctive white wing stripe along the tips, extending from the greater secondary coverts to the greater primary coverts.

Non-Breeding Plumage Overview

Plumage varies by season and life stage. Non-breeding plumage has greyish upperparts and white underparts that sometimes have large grey streaks; as feathers wear, both upperparts and underparts gradually become browner.

Upperpart Feather Details

Upperpart feathers have darker centers, especially on the crest, that give the upperparts a mottled appearance. Upper tail coverts and lower rump feathers are white, with broad, pale grey rectrices.

Wing Feather Traits

Primaries and secondaries are dusky, with white streaks along the shaft and a white tip.

Non-Breeding Head Markings

It has a distinct white supercilium, a stripe running across the head, paired with grey-brown lores, the area around the eyes, and auriculars, the feathers that protect the ear.

General Moult Pattern

Moult timing and extent follow a consistent pattern.

Post-Breeding Moult

The post-breeding moult is a complete moult that replaces all feathers, occurring from July to November, and can last as late as the following April for some southern populations.

Spring Moult

The spring moult, occurring from January to May, is a partial moult that only replaces body feathers, not flight feathers.

Breeding Sexual Dimorphism

Returning breeding curlew sandpipers are sexually dimorphic.

Breeding Female Plumage

In females, the front of the body, entire head, and upper back have variable reddish tinting, with grey-to-dark streaks. Lower scapulars, feathers around the shoulder where the upper wing meets the body, alongside upperwing coverts and commonly tertials, the flight feathers closest to the body, have ruddy-silver tips and black centers, creating a spotty appearance.

Breeding Female Rump and Wing Feathers

Upper tail coverts, upperwing coverts, the rump, and most flight feathers look nearly identical to their non-breeding appearance, with the exception of central rectrices and 2 to 3 tertials, which are off-black with white or ruddy fringing.

Breeding Male Plumage

Male plumage is similar to female plumage, except the rufous tinting is almost completely solid, with conspicuous spots above the eye and around the crown.

Pre-Juvenile Moult

The pre-juvenile moult of chicks takes place at the nest site from late June to July.

Juvenile Plumage

Juveniles look similar to adult non-breeding plumage, but have more evenly distributed wear marks and fringing, which creates a scaly, more buff-tinged appearance. Both the crown and nape are dusky with pale creamy streaks, and the nape is slightly paler; juvenile rectrices are tapered and narrower.

Post-Juvenile Moult

The post-juvenile moult, occurring from October to December and able to finish as late as April, is a partial to incomplete moult that replaces body feathers and some flight feathers. This moult occurs almost entirely at stopover and overwintering sites, and only rarely starts at the breeding grounds.

Yearling Pre-Breeding Moult

The pre-breeding moult of yearling birds, which occurs from April to June, is either absent or limited; body feathers are largely or completely replaced, but few if any flight feathers are replaced.

First-Time Breeder Plumage

The plumage of first-time breeders is similar to adult summer plumage, with the main difference being white spots or tufts on the underparts, which are fully, opaquely rufous rather than just tinted. Sex differences in first-time breeders match those of returning breeders.

Migration Distribution

In terms of distribution and habitat, curlew sandpipers are found across large areas of Afro-Eurasia during migration, and are notably absent east of the Verkhoyansk Range in eastern Siberia and across southern inland Asia during this period.

Breeding Range

They breed exclusively in the Siberian Arctic, from the Yamal Peninsula to Kolyuchin Bay.

African Non-Breeding Range

Their non-breeding range covers coastal regions of West Africa from Gabon to Mauritania, including Cape Verde, and southern Africa, spanning inland from Mozambique to Namibia to South Africa, and north through Uganda to Kenya. They also occur, though more rarely, inland from Niger to Chad, across the Republic of the Congo to Angola, along the Nile from Sudan to Egypt, and in southeastern Tunisia.

Australasian Non-Breeding Range

They are much rarer along the coasts of Australasia, as well as inland Victoria and New South Wales. In New Zealand, they occur on the southeastern coast of the South Island and the entire coastline of the North Island.

Asian and Vagrant Range

They also overwinter in coastal South Asia and Southeast Asia, and do not overwinter anywhere else in Eurasia. The curlew sandpiper is a common migratory vagrant in North America, particularly along the Atlantic Seaboard.

Non-Breeding Habitat

During the non-breeding season, curlew sandpipers are most often found on sheltered mudflats, as well as salt pans and wetland edges. In inland areas, they occupy the edges of various bodies of water, especially those with muddy or sandy margins, and can also be found along sewage ponds.

Migration and Breeding Habitat

They use both coastal and inland wetlands during migration. During the breeding season, they mostly stay in lowland tundra near bogs, depressions, or pools, staying away from scrub and other dense vegetation.