Red knots, known simply as ‘knots’ in the UK are medium-sized shorebirds that undertake impressive annual migrations of up to 30,000 km (18,000 mi) each year between Arctic breeding grounds and southern coastal wintering habitats.
Red Knot, non-breeding plumage
Juvenile Red Knot
Red Knot, breeding plumage, in-flight over the sea
Family:Sandpipers, snipes and phalaropes
23cm to 25cm
47cm to 54cm
125g to 215g
The knot is a dumpy, short-legged, stocky-wading bird. In summer, it has a deep reddish breast face and belly, from salmon pink to brick red. Its crown is brown streaked with lighter markings, with brownish shoulder streaks, and a dark brown and black marbled back, wings and tail, with lighter fringing that gives a scaled appearance. The undertail area is pale white. Legs are brownish yellow, eyes are black and the bill is dark.
Breeding female red knots are similar in appearance to males, but their plumage is less vibrant and the red colouring is less extensive.
In winter, males and females are like, with grey upperparts, fringed with white, wing coverts tipped with white which creates a white line across the wing that is visible in flight. A pale white rump can also be seen in flight. Their underparts are white, with some faint streaking. Their head is grey with a paler eye stripe.
Juvenile red knots are darker than non-breeding adults, with charcoal gray feathers fringed with white on their mantle, back, and wings, creating a scaled effect. Their head, face and throat are a streaky gray and white, with a faint white eye stripe. Their flanks are tinged with buff, and their belly is pale off-white with some darker streaked gray markings.
Red Knot, breeding plumage
Red Knot, non-breeding plumage
Red knots are medium-sized, stocky wading birds, with relatively short legs. There are only slight differences in size between the sexes, with some overlap in the range between the marginally larger male and the smaller female.
Red Knot standing on the sandy beach
When foraging alone, red knots are usually silent, but low-pitched ‘knutt’ calls can be heard when they are flying or feeding as part of a larger flock. During migration, a two-note ‘knuup-knuup’ cry can be heard. During courtship, males can be heard uttering a light, reedy ‘poor-me’ call.
Red Knot, non-breeding, foraging along the coast
Worms, insects and their larvae, snails, and spiders are the chief foods eaten by red knots on their Arctic breeding grounds. Early arrivals to breeding grounds may eat shoots and plant matter if the landscape is not fully thawed for insect life to be widely available.
On migration and during winter months, their diet changes to include more shellfish and molluscs, including mussels, estuarine and saltwater clams. The eggs of horseshoe crabs are particularly important, with Delaware Bay being a major stopover point on northward migrations each spring.
Soon after hatching, red knot chicks are able to forage for their own prey and their early diet mainly comprises insects, particularly adult midges.
Pair of Red Knots foraging in seaweed on the beach
Red knots nest on Arctic tundras, and spend winters in very different environments, heading mostly to coastal waters in the southern hemisphere.
Sunny arctic tundras with sloping landscapes and only sparse vegetation are preferred sites for nesting. Foraging grounds at streams and ponds are nearby, and usually coastal or only a short distance inland.
In winter, coastal regions are preferred, with large flocks of red knots making stopovers to forage for crustaceans en route. Muddy estuaries, sandy beaches, peat banks, brackish lagoons, and tidal bays are all common destinations offering abundant winter foraging opportunities for red knots until they head north to breed again the following spring.
Red knots have an extremely large range. Breeding occurs from Alaska across northern Canada to Greenland and across the far northern regions of Russia. Wintering grounds are located on the Pacific and Atlantic coasts of North and South America, in north-western Europe, on the western coast of Africa from Tunisia and Morocco as far south as South Africa, across southern Asia and around Australia.
Red knots can be divided into six distinct subspecies, according to geographical location.
The global population of red knots is estimated at between 891,000 and 979,000 individuals, and although numbers are in an evident decline, they are still a relatively common sight once they begin their post-breeding migrations, particularly en route to wintering grounds when large flocks gather to refuel at beaches and estuaries.
Red Knot, non-breeding, in-flight over the mudflats
Delaware Bay is a famous stopover site associated with vast flocks of red knots on migration, with up to 80 percent of the Canadian breeding population visiting to refuel on the way to wintering grounds in Florida, Texas, Brazil, and southern South America.
The Canadian Arctic regions host up to 80,000 breeding individuals each year. Two subspecies are present with the north-eastern islands of Ellesmere Island, Prince of Wales Island, and Somerset Island a key breeding ground for Caldiris canutus islandica, while further south, from Baffin Island to Hudson Bay the Caldiris canutus rufa subspecies is widespread.
Around 265,000 knots arrive each year to spend winter in the UK. Sightings are regularly reported along the entire coastlines of England, Scotland, and Wales, but the best chances of a sighting are at muddy estuaries, with large concentrations regularly appearing at The Wash, Morecambe Bay, the Thames, Humber, and Dee estuaries, the Solway Firth and Strangford Lough in Northern Ireland.
Flock of Red Knots in-flight over the sea
A life expectancy of around 8 years is typical for red knots, with breeding for the first time at two years. Much older birds have been identified through banding records, including an individual that reached 27 years and 3 months in 2006.
On breeding grounds, Arctic foxes, skuas, and gyrfalcons will opportunistically raid red knot nests for eggs and target hatchlings. On migration, and at wintering grounds, predators including great black-backed gulls, peregrine falcons, harriers, merlins and short-eared owls may prey on adult birds.
Red knots and their habitats are the subjects of various official conservation acts around the world. In 2014, the rufa subspecies of the red knot was listed as a federally threatened species under the United States Endangered Species Act – the second-highest status possible for a subspecies.
Legislation including the Migratory Birds Convention Act, 1994, in Canada, the Migratory Bird Treaty Act of 1918 in the US, and the Wildlife and Countryside Act, 1981 in the UK, offer protection to red knots against being killed, captured, or injured.
Red knots have been classified with Near Threatened status by the IUCN, due to steep declines in population in recent decades, particularly in the East Asian and Australian wintering subpopulations. The U.S. Shorebird Conservation Plan lists the red knot as a “Species of High Concern,” due to declining population trends and threats to wintering grounds. In the UK, knots have Amber status on the British Birds of Conservation Concern list.
Climate change is a serious threat to the habitats of red knots, and already habitat loss due to land reclamation in the Yellow Sea has already had a negative impact on the population numbers in the wintering populations in East Asia and Australia.
Harvesting of horseshoe crabs in major stopover points during the southward migration of red knots is another factor in the worrying population declines.
Red Knot standing in shallow water on the beach
Ahead of females arriving on breeding grounds, male red knots prepare up to five shallow scrapes in the ground, stripping out any vegetation and pressing a depression into place using their breast. Dried grasses, leaves, and lichen may then be added as an extra lining that offers insulation against the frozen land.
Red knots’ nesting period varies according to geographical location, but the peak laying period is in mid to late June and is usually complete by early July. Incubation is left to the male alone, and the young hatch after 21 to 22 days.
Eggs laid by red knots are stone coloured, with darker brown speckling. They measure 43 mm by 30 mm (1.7 in by 1.2 in) and usually four eggs are laid. One clutch a year is typical, as females leave the breeding grounds shortly after they’ve laid their eggs.
Red knots pair up on breeding grounds on arrival, and the pair bond is not long-lasting, with females departing from the site once they have laid their eggs, leaving males to incubate and raise young alone. Different mates are chosen each season, although males do show strong fidelity to previously used nesting sites.
Red Knots in nesting habitat
Outside of the breeding season, red knots gather in vast flocks to migrate and forage for crustaceans at sea. They are a social species and no hostility or conflict is shown towards other birds.
When breeding, aggressive physical interactions with other birds remains rare, and any fights are short-lived and relatively mild, with posturing generally as fierce or confrontational as it gets.
Red knots roost alongside each other in large flocks, packed tightly together, and sometimes surrounded by other shorebirds. Roosting sites are on shores, a short distance from feeding grounds. A one-legged roosting stance is most common, helping to stabilize their bodies in windy weather.
Red Knots in confrontation
Red knots are known for their long-distance migrations between their circumpolar breeding grounds and wintering habitats deep in the southern hemisphere.
Outside of the spring and summer breeding season, it becomes impossible for red knots to survive in the Arctic landscapes in which they’ve raised their young due to frozen ground and a lack of suitable food resources.
They no longer rely on the insects, larvae, snails, and worms which give their offspring vital energy in the early stages of life, and their diet changes to molluscs and marine invertebrates that are widely available in the marine waters they spend their winters foraging in, particularly the eggs of horseshoe crabs.
A true long-distance migrant, red knots cover distances of up to 15,000 km (9000 mi) between their breeding grounds and winter habitats.
Red knots breed in the High Arctic regions of North America, Greenland, and Siberia. Once breeding is complete, they migrate south to coastal waters off South America, Africa, Europe, Australia and New Zealand. Some subpopulations may not cover such epic distances, settling for the winter in Western Europe and coastal regions of the southeastern United States.
Red Knots, non-breeding, in-flight
Red knots are wading birds, in the same family as snipes, sandpipers and phalaropes.
Red knots are fascinating to researchers who are able to gain valuable insights into their lengthy migration patterns due to banding programs which are used to understand trends in population decline and changes to habitats worldwide.
Due to the vast numbers that descend upon Delaware Bay each year to feed on the eggs of horseshoe crabs, the species is directly linked to bringing in a significant amount of money to the local economy, with ecotourism in this region raising around $36 million annually.
Moonbird is the nickname given to an individual red knot, tagged as B95, which is the oldest known individual of its species and the subject of books and documentaries. The nickname ‘moon bird’ originates from the fact that during this bird’s lifetime, its long-distance migrations have exceeded the length of the journey from Earth to the Moon.
The Eurasian woodcock spends days roosting in dense, damp woodland undergrowth, and evenings and nights foraging in open fields as well as woods for worms and beetles.
The UKs breeding population of Wood Sandpipers are limited to an area of swampy marshland in the Highlands of northern Scotland, although they are far more commonly sighted in passage during their spring and autumn migrations as they make brief stopovers in southern and eastern England.
A long-legged wader, closely related to the curlew, the Eurasian whimbrel, has small breeding populations established on the Scottish islands of Shetland and Orkney. Migrating whimbrels may be spotted along Britain’s coastlines as they undertake long-distance migration flights between Arctic tundra breeding grounds and wintering territories in Africa.
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Sanderlings run tirelessly along sandy beaches, rushing down to feed as the waves recede and sprinting back, seemingly hoping to keep their feet dry. Their comical antics and non-descript looks belie an impressive avian that makes remarkable migrations between Arctic nesting grounds and overwintering grounds as distant as the southern tips of South America and South Africa.
A rare breeding wading bird in the UK, ruffs are among the most intriguing bird species on Earth, due to the diversity not just between males and females, but also between the three distinctly different types of males that occur.
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A hardy wading bird that thrives in the bleak Arctic tundra landscapes of northeastern Canada, Greenland and Iceland, purple sandpipers arrive on wintering grounds along the northeastern coast of the United States and the UK each autumn, to forage for molluscs and crustaceans on rocky shores and coastal headlands.
Pectoral Sandpipers are mid-sized waders that breed on wet tundra landscapes across the northernmost extremes of North America and the Siberian Arctic. Their epic annual migration return trips of up to 30,000 km are one of the most lengthy of any bird species, similar to those undertaken by the Arctic tern.
One of the world’s smallest wading birds, little stints cover enormous distances on their annual migrations between breeding grounds in the Arctic Circle and winter territories in southern Africa and South Asia. A handful of individual birds spend winter in the UK, and records of vagrant birds reaching North America are occasionally reported.
Highly camouflaged and elusive, the jack snipe is a small wading bird that spends winters on mudflats and freshwater wetlands across Britain. Smaller and less common than the UK’s other native snipe, the common snipe, jack snipes are harder to spot due to their tendency to crouch low and remain hidden among reeds.
The grey phalarope’s winter and summer plumage are so distinctly different that the species is known by an entirely different name in the US. In the UK, the bird’s name reflects its post-breeding plumage, which is dominated by light grey and white. However, in the US, it is known as the red phalarope, after the more vibrant orange-red plumage seen during the breeding season.
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Identified as being from a group of birds known as Waders, within North America they are generally referred to as Shorebirds. This monotypic species, a long distance migrant, is considered to have an Amber Conservation Status otherwise known as Near Threatened.
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