Stilt Sandpiper

Long greenish-yellow legs, a drooping bill, and a plump belly give the Stilt Sandpiper a subtly hunched, front-heavy silhouette unlike any other North American sandpiper. At 18–23 cm long with a wingspan of 37–42 cm, it sits between a Sanderling and a Lesser Yellowlegs in size, but its proportions are all its own. A long slender neck and a long bill that droops slightly at the tip complete the picture.

In breeding plumage (April–August), adults are unmistakable. Heavily and neatly barred dark brown and white, the underparts are unlike those of any other North American sandpiper. The back is dark brown with darker feather centres, and the head carries a rich chestnut crown and ear patch, a bold white supercilium, and a dark loral stripe running in front of the eye. The bill is black. No other North American sandpiper combines this head pattern with barred underparts.

In non-breeding (winter) plumage, the bird becomes considerably plainer: pale grey above with fine white feather fringes, whitish below with a dusky grey wash on the breast. The bold white supercilium persists year-round and remains the most reliable single field mark. The greenish-yellow legs are constant across all plumages.

Juveniles resemble non-breeding adults in their strong head pattern but show a scaly appearance on the upperparts, where neat pale edges to dark feathers create a more textured look than the smooth grey of winter adults. The underparts are whitish with brownish streaking on the chest, and the back is darker overall.

The sexes are similar in plumage at all seasons and are not reliably distinguished in the field. Females tend to be slightly larger on average.

For most of the year, the Stilt Sandpiper passes almost unheard — but on the Arctic breeding grounds, the male calls incessantly from the air throughout the long summer day. The contrast could hardly be greater: a bird that migrates in near-silence becomes one of the most vocal presences on the tundra once it reaches its nesting territory.

The most commonly heard call away from the breeding grounds is a low, soft "tu-tu" or "tew" note — similar in character to the call of the Lesser Yellowlegs but noticeably softer and less strident. Some observers describe it as a flat "toff." Xeno-canto recordings also document a mild rolling "trrrr" and various soft contact calls given within flocks. When flushed, birds may give a slightly sharper version of the basic call.

On the breeding grounds, the male is a very different proposition. During the aerial courtship and territorial display, he calls incessantly — a guttural, continuous vocalisation described as a series of musical, low "twew" notes interspersed with coarse calls and whines, delivered during the spectacular plummeting display flight. Pairs on the breeding grounds also exchange a variety of interaction calls during nest relief and chick-tending.

The low, unobtrusive quality of the call means that Stilt Sandpipers are often detected visually before they are heard — particularly on migration, where a group may be feeding silently in a flooded field with no audible indication of their presence.

In North America, the best time to find Stilt Sandpipers is during autumn migration, which runs from late June through early September. Adults move first — failed breeders from late June, successful females through July, adult males through late July — with juveniles following from late July into September. Spring migration through the central Great Plains peaks in April and early May. Cheyenne Bottoms Wildlife Area in Kansas is arguably the single best site in the world for the species, regularly hosting hundreds of birds; other reliable sites include the Rainwater Basin in Nebraska and flooded fields throughout Iowa, Minnesota, and Missouri.

Look for Stilt Sandpipers in shallow freshwater pools and flooded fields rather than on tidal mudflats. The feeding action is the clincher: a bird wading belly-deep and probing rhythmically is almost certainly a Stilt Sandpiper or a dowitcher. Check the leg colour — greenish-yellow legs immediately separate it from the two dowitcher species, which have greenish-grey legs.

Breeding-plumaged birds (April–August) are straightforward: the combination of chestnut cheek, bold white supercilium, and heavily barred underparts is unique among North American shorebirds. Non-breeding and juvenile birds require more care — focus on the persistent white supercilium, the long drooping bill, and the greenish-yellow legs. Flushed birds reveal plain wings with no wingbar, a white rump, grey tail, and long legs projecting well beyond the tail tip.

In the UK, any autumn shorebird with long greenish-yellow legs, a drooping bill, and a bold supercilium should be scrutinised carefully. Most records fall between late July and October, with coastal wetlands in East Anglia and Yorkshire the most likely locations. Given that only a handful of records exist for Britain, a confirmed sighting would be a major event.

On the breeding grounds, the Stilt Sandpiper's diet is approximately 90% invertebrates. Adult beetles — particularly diving beetles and their larvae — dominate, alongside adult and larval flies (craneflies, midges, mosquitoes), water bugs, water boatmen, small snails, and occasionally small frogs. Birds also forage on dry tundra ground during the breeding season, picking prey from the surface as well as probing into soft substrate.

During migration and winter, the diet broadens to include a wider range of aquatic invertebrates: beetle larvae, fly larvae, marine worms, small molluscs, and small crustaceans. Plant matter becomes considerably more important away from the breeding grounds — seeds of knotweed, river hemp, and plants in the family Asteraceae can make up as much as 30% of the diet during migration. Leaves and roots of aquatic plants are also consumed.

Foraging is primarily tactile. The bird wades into water up to belly depth and probes rhythmically into soft mud, the sensitive bill tip detecting prey by touch. This allows it to feed effectively in turbid water where visual hunting would be impossible, and explains why it feeds at night as readily as during the day. It also hunts visually, picking prey from the water surface, particularly when targeting larger or more mobile items.

The shift from an almost entirely invertebrate diet in summer to one that includes significant plant material in autumn reflects the seasonal availability of seeds at stopover sites. It also reflects the energetic demands of fuelling long migratory flights across the Caribbean.

Males arrive on the Arctic breeding grounds a few days ahead of females in late May to early June and immediately begin establishing territories. Laying typically starts in the first half of June. The male makes several scrapes in the tundra — usually on a dry low ridge, raised hummock, or top of a sedge hummock, often surrounded by water or wet ground — and the female selects one as the nest site.

The nest is a shallow depression, averaging about 10.4 cm across and 3 cm deep, lined with willow and birch leaves, grasses, sedges, cotton grass, horsetail, mosses, and lichens.

Clutch size is typically 4 eggs (range 2–5), described as light green to olive green, heavily dotted with dark brown. Both parents share incubation duties over approximately 19–21 days: the female incubates at night, the male during the day. Nests are usually at least 100 m apart; in prime habitat at Churchill in the 1960s, average internest distance was 300–400 m.

Chicks are precocial and leave the nest within a day of hatching, finding all their own food from the start. Both parents initially tend and defend the brood, but the female typically departs when the chicks are only 2–3 days old. The male remains until the chicks are 10–14 days old, then also departs before the young can fly well. Young fledge at approximately 17–18 days. Each pair raises only one brood per season, and the species does not generally breed until two years old.

The mating system is monogamous, and some pairs may mate for life. Breeding site fidelity is high: studies at Churchill found that up to 50% of pairs at a given location return to breed in consecutive years. Established pairs with high site fidelity may dispense with courtship displays entirely, going straight to nest preparation on arrival.

In flight, the Stilt Sandpiper has a distinctive silhouette: a hump-backed profile with the head held slightly low, long legs trailing well beyond the tail tip, and a relatively long, narrow wing. The wings are plain — only a faint pale stripe is visible, with no bold wingbar — which immediately distinguishes it from many similar-sized shorebirds such as the Dunlin or Pectoral Sandpiper. The rump is white and the tail grey, creating a clean white patch above the tail that is visible from a considerable distance.

The underwings show grey and white. The long legs projecting beyond the tail are a reliable feature at any distance, giving the bird a more attenuated rear end than most sandpipers of comparable size. The overall impression in flight is of something intermediate between a dowitcher and a yellowlegs — longer-legged than the former, plainer-winged than the latter.

Flight is direct and purposeful on migration, with measured wingbeats rather than the erratic, twisting flight of smaller waders. Migration is conducted in groups of up to several tens of individuals, in stages of several hundred kilometres, with non-stop flights both day and night. Flight speed has been measured at 64–72 km/h. During the male's breeding display, flight becomes highly acrobatic: he raises his wings in a deep "V" over his back and plummets toward the ground while singing and rocking from side to side.

During autumn migration, when juveniles follow adults, the route spreads out and some birds stray to the Atlantic and Pacific coasts. The species is a rare vagrant to western Europe, Japan, and Australia, presumably as a result of birds being displaced from their normal routes.

The typical lifespan of a Stilt Sandpiper in the wild falls between 5 and 9 years, though individuals regularly exceed this. The oldest recorded individual was at least 11 years and 1 month old when recaptured and rereleased during banding operations in Texas, placing it among the longest-lived small shorebirds on record.

Annual survival rates are not well documented for this species, but the demands of long-distance migration — including the overwater crossing of the Caribbean — represent the most significant mortality risk outside the breeding season. Collision with power lines during migration is a documented cause of death. On the breeding grounds, nest predation and habitat degradation (particularly from Snow Geese) reduce productivity, and the species does not breed until two years old, meaning young birds must survive two full migration cycles before contributing to the population.

The high breeding site fidelity documented at Churchill — with up to 50% of pairs returning in consecutive years — suggests that experienced adults have relatively high annual survival once they reach breeding age. This is consistent with the life-history strategy of a long-distance migrant that invests heavily in each breeding attempt.

The Stilt Sandpiper is currently listed as Near Threatened on the IUCN Red List (2024 assessment), with a global population estimated at approximately 1.2 million mature individuals. The Canadian population alone is estimated at 500,000–1,000,000 adults, giving Canada an exceptionally high responsibility for the species' global survival.

The population trend is declining. The 2025 State of the Birds report (USA) lists the Stilt Sandpiper as an Orange Alert Tipping Point species. This designation means it has lost more than 50% of its population over the past 50 years and has shown accelerated declines within the past decade. Partners in Flight rates it 15 out of 20 on the Continental Concern Score. The most dramatic documented decline occurred at Churchill, Manitoba: breeding density fell from 12–16 pairs per 100 ha in the 1960s to just 2–4 pairs per 100 ha in the 1990s — a reduction of roughly 90% over 30 years. However, populations in Alberta and at Prudhoe Bay, Alaska appear to be increasing, suggesting a possible westward shift in breeding distribution rather than a uniform collapse.

The primary threat on the breeding grounds is habitat degradation caused by overabundant Snow Geese and Canada Geese, which graze heavily on grasses, sedges, and rhizomes, destroying tundra structure. At Churchill, hatching success fell from 91% of nests in the 1960s to 68% in 1992–1996, directly linked to goose-driven habitat loss.

Beyond the goose problem, several further pressures compound the decline. Warming temperatures are drying fens and driving shrub and tree encroachment through isostatic rebound, shifting prey availability on the breeding grounds. Petroleum and gas development threatens key breeding areas in Alaska, while on migration and wintering grounds the main risks are loss and drainage of freshwater wetlands in South America and hunting in the Caribbean. Collision with power lines is an additional documented mortality cause. The species is listed as a USFWS Bird of Conservation Concern. No specific management plans are currently in place.

Start with the legs: long, greenish-yellow, and immediately visible at distance, they lift the bird noticeably higher than a Dunlin or Pectoral Sandpiper. Add a drooping bill tip and a plump belly and you have a distinctive hunched, front-heavy silhouette unlike any other sandpiper. The bill droops where a yellowlegs' bill is straight.

In breeding plumage (April–August), identification is straightforward: the combination of chestnut cheek, bold white supercilium, and heavily barred underparts is unique among North American shorebirds.

Non-breeding and juvenile birds require more care. Focus on the persistent bold white supercilium (present year-round), the long drooping bill, and the greenish-yellow legs. Juveniles show a scaly, textured upperpart pattern with neat pale feather edges.

The most common confusion species are the two dowitchers (Short-billed and Long-billed), which share the sewing-machine feeding action. Dowitchers have shorter, greenish-grey legs, a straight bill, and a bold white wedge up the back visible in flight — the Stilt Sandpiper's back is plain. Lesser Yellowlegs shares the long legs and upright stance but has a straight bill, yellow (not greenish-yellow) legs, and spotted rather than barred underparts in breeding plumage.

In flight, look for the plain wings (no wingbar), white rump, grey tail, and long legs projecting well beyond the tail tip. The hump-backed silhouette is distinctive. The call — a low, soft "tew" — is quieter and less carrying than a yellowlegs' sharp whistle.

The male's courtship display is built around a deep-V wing posture and a plummeting dive that sets it apart from the more horizontal display flights typical of other Calidris-group sandpipers. He pursues the female in the air, flies ahead of her, then raises his wings sharply over his back and plummets toward the ground while singing continuously and rocking from side to side. A lower-altitude display — shallow wingbeats while circling the female — may alternate with the plummeting dive.

Males arrive on the breeding grounds a few days before females and begin displaying immediately, calling incessantly from the air throughout the long Arctic day. The display song is a guttural, continuous vocalisation: a series of musical, low "twew" notes interspersed with coarse calls and whines, delivered at full volume during the aerial display. This performance serves simultaneously as courtship to the female and territorial advertisement to rival males.

For details of nest construction, clutch size, incubation, and breeding site fidelity, see the nesting and breeding section above.