Great Knot

The Great Knot is the heavyweight of the calidrid sandpipers, a stocky, barrel-chested wader that packs more bulk than any of its close relatives. It breeds in the cold, stony uplands of northeastern Siberia and spends the rest of the year thousands of kilometers away on the warm intertidal mudflats of Southeast Asia and Australia. Between those two worlds lies one of the most demanding migrations undertaken by any bird.

It is a flagship species of the East Asian-Australasian Flyway, a chain of coastal wetlands running from the Russian Arctic to Australia and New Zealand. Great Knots depend on a small number of rich staging grounds, above all the tidal flats of the Yellow Sea, where they refuel on migration. Vast flocks once gathered there to gorge on shellfish before pressing on. Large-scale reclamation of those flats for ports, farmland, and industry has removed vital feeding areas and driven steep, well-documented declines, and the species is now listed as Endangered. Where good habitat remains, flocks still mass in the thousands, wheeling in tight, smoke-like formations over the mud, a reminder of how much this bird still has to lose.

The Great Knot is a large, deep-chested sandpiper with a fairly long, straight bill that tapers slightly toward the tip. It looks distinctly front-heavy and short-legged compared with most waders. Plumage changes dramatically through the year, so the season matters as much as any single field mark, and its closest lookalike is the smaller Red Knot, which shares the same mudflats.

Male vs. female

The sexes look alike and cannot be reliably separated in the field. Both show the same seasonal plumages, and any differences are averages rather than clean field marks: breeding females can average slightly less intensely marked than males, with a little less black on the breast and duller chestnut in the scapulars, but the overlap is large. Females also tend to carry a marginally longer bill on average. In practice, birders identify Great Knots by species and season rather than by sex.

Juveniles

Juveniles are the neatest-looking plumage. Fresh young birds are grey-brown above with a scaly pattern created by pale feather fringes and small dark subterminal marks, giving a tidy, scalloped back. The breast is washed buff and finely streaked rather than boldly spotted, and the overall effect is cleaner and warmer-toned than a worn non-breeding adult. Juveniles appear on southbound migration in late summer and autumn, and they gradually molt into the plain grey first-winter plumage as the season advances.

Away from the breeding grounds the Great Knot is a fairly quiet bird. In flight and among feeding flocks it gives a low, soft, muffled double note, often written as a subdued nyut-nyut or chucker-chucker, easily lost in the general murmur of a mixed wader flock. It is far less vocal than many shorebirds and rarely draws attention by voice alone.

On the Siberian breeding grounds males become much more demonstrative. They perform high, circling display flights over the tundra, delivering more elaborate rolling trills and plaintive whistled phrases that carry across the open slopes. These songs are seldom heard by birders elsewhere, since almost all encounters away from the Arctic are with silent or near-silent birds on the mud.

The Great Knot breeds only in the alpine and subalpine zones of northeastern Siberia, in a restricted band of mountain tundra in the Russian Far East. This is one of the smallest breeding ranges of any common flyway wader, which is part of why the species is so vulnerable.

On migration it becomes almost entirely coastal and funnels through the East Asian-Australasian Flyway. The tidal flats of the Yellow Sea, shared by China and the Koreas, are the single most important staging area, where huge numbers pause to feed and lay down fat. From there birds continue to wintering grounds along the coasts of Southeast Asia, Indonesia, New Guinea, and above all northern and northwestern Australia, where sites such as Eighty Mile Beach and Roebuck Bay hold internationally significant numbers. Throughout the non-breeding season it favors w ide, open intertidal mudflats, sandflats, and sheltered estuaries, and it is only rarely seen inland or on rocky shores.

The Great Knot is a shellfish specialist. Its main food is small bivalve molluscs, which it detects in soft intertidal mud using the sensitive tip of its bill and swallows whole. It then crushes the shells internally in a powerful muscular gizzard, a strategy that lets it process large numbers of hard-shelled prey quickly without having to open each one. It also takes marine worms, small crustaceans, and other invertebrates from the mud.

At migration stopovers feeding becomes a race against time. Birds spread across the flats on falling tides and probe intensively, packing on fat and rebuilding the flight muscles they will burn on the next long leg. The quality and extent of shellfish beds at staging sites directly limits how much fuel a bird can store, which is exactly why the loss of the richest Yellow Sea flats has hit the species so hard.

The Great Knot nests on the ground in dry mountain tundra and on stony, sparsely vegetated slopes, often near patches of lichen and low scrub. The nest is a simple shallow scrape lined with lichen, leaves, and other fine plant material, well hidden against the mottled ground where the incubating adult sits low and nearly invisible.

A typical clutch is four eggs. Both adults share incubation, and the eggs hatch into downy, cryptically patterned chicks that leave the scrape within a day or so and feed themselves under close parental guard. As with many Arctic-breeding waders, the young grow fast during the brief northern summer, and adults often depart the breeding grounds before the fully grown juveniles, which make their first southward migration on their own.

The Great Knot is not a backyard bird and cannot be attracted to a garden. It is a specialist of open coastal mudflats, so the realistic goal is knowing where and when to go to see one. With the species now Endangered, respectful, low-impact watching also matters, because disturbing feeding or roosting flocks costs birds the energy they need for migration.

• Head for extensive intertidal mudflats and estuaries along the East Asian-Australasian Flyway, the habitat Great Knots depend on for feeding.
• In the non-breeding season, focus on northern and northwestern Australia, where sites such as Roebuck Bay and Eighty Mile Beach hold large numbers.
• During migration, coastal wetlands around the Yellow Sea and wider East Asia host major staging flocks, best timed for northward passage in spring and southward passage in autumn.
• Time visits to a rising or falling tide, when birds are pushed close to shore to feed or gather at high-tide roosts.
• Bring a spotting scope and scan mixed wader flocks for the larger, deeper-chested, longer-billed Great Knots among Red Knots and other sandpipers.
• Keep your distance from roosting and feeding flocks and avoid flushing them, since repeated disturbance drains the fat reserves migrants rely on.

• Red Knot: Smaller and shorter-billed, with uniform brick-red underparts when breeding rather than a spotted breast and chestnut shoulder patches
• Bar-tailed Godwit: A larger flyway migrant with a much longer, slightly upturned bill and longer legs
• Grey Plover: A plump grey shorebird of the same mudflats but with a short bill and diagnostic black armpits in flight