Knot

Appearance

The knot (Calidris canutus, sometimes referred to as the red knot) is a bulky, smallish wader that measures around 23-25 centimetres (9-10 inches) in length. It has short greenish legs and a straight bill. In winter its plumage is grey above and pale below, but in summer it looks very different, being brick red below and speckled black above. The rump is pale grey and the darker wings have a thin white bar.

Juvenile birds are slightly slimmer than adults and have a pinky buff wash on the chest and browner underparts.

Habitat and distribution

The knot is a migrant bird that breeds mainly in north-east Canada, Iceland and Greenland and winters in Britain. There are also populations that breed in Siberia and can be seen in Britain in May as they migrate to Africa.

The wintering flocks in Britain gather in huge numbers on large sandy estuaries such as Morecambe Bay and The Wash. Others are found on the rocky coasts of eastern Scotland. It is estimated that as many as 250,000 knots may winter in Britain.

Behaviour and feeding

The flocks are extremely tight and give rise to the collective term of a “pack” of knots. When the birds take off they offer a spectacular sight as they perform complex aerial manoeuvres in which the patterns change constantly as the upper and then the lower sides of the birds come into view.

Knots will feed on insects in summer but in winter they gorge themselves on small cockles and Baltic tellins, which are small saltwater clams. The knots dig these from the mudflats at low tide by probing with their bills. At high tide the birds roost in tight packs close to the water’s edge.

Breeding

The knot’s breeding season is very short. They arrive at their breeding grounds in May and leave in August and must therefore make the most of the brief Arctic summer. The breeding grounds are on islands and remote plateaux. Three or four eggs are laid and are incubated by both parents, this taking no more than 22 days. The young birds are able to fly after only 20 days at the most and are then fully independent. Female knots often leave the family before the young birds have fledged.

Conservation

Knots are dependent for their long-term survival on the continued availability of their winter feeding grounds. Because these are relatively few in number, any drastic changes to these sites would have a serious effect on knot populations. Developments such as barrages, other large-scale human activity, or a general rise in sea level, could therefore pose a severe threat.

© John Welford