Red knot

Appearance

An adult red knot is the second largest "Calidris" sandpiper, measuring 23–26 cm long with a 47–53 cm wingspan. The body shape is typical for the genus, with a small head and eyes, a short neck and a slightly tapering bill that is no longer than its head.

It has short dark legs and a medium thin dark bill. The winter, or basic, plumage becomes uniformly pale grey, and is similar between the sexes. The alternate, or breeding, plumage is mottled grey on top with a cinnamon face, throat and breast and light-coloured rear belly. The alternate plumage of females is similar to that of the male except it is slightly lighter and the eye-line is less distinct.

Distribution

In the breeding season, the red knot has a circumpolar distribution in the high Arctic, then migrates to coasts around the world from 50° N to 58° S. The red knot has one of the longest migrations of any bird. Every year it travels more than 9,000 mi from the Arctic to the southern tip of South America.

Reproduction

The red knot is territorial and seasonally monogamous; it is unknown if pairs remain together from season to season. Males and females breeding in Russia have been shown to exhibit site fidelity towards their breeding locales from year to year, but there is no evidence as to whether they exhibit territorial fidelity. Males arrive before females after migration and begin defending territories. As soon as males arrive, they begin displaying, and aggressively defending their territory from other males.

The red knot nests on the ground, near water, and usually inland. The nest is a shallow scrape lined with leaves, lichens and moss. Males construct three to five nest scrapes in their territories prior to the arrival of the females. The female lays three or more usually four eggs, apparently laid over the course of six days. The eggs measure 43 mm × 30 mm in size and are ground coloured, light olive to deep olive buff, with a slight gloss.

Both parents incubate the eggs, sharing the duties equally. The off duty parent forages in flocks with others of the same species. The incubation period lasting around 22 days. At early stages of incubation the adults are easily flushed from the nest by the presence of humans near the nest, and may not return for several hours after being flushed. However in later stages of incubation they will stay fast on the eggs. Hatching of the clutch is usually synchronised. The chicks are precocial at hatching, covered in downy cryptic feathers. The chicks and the parents move away from the nest within a day of hatching and begin foraging with their parents. The female leaves before the young fledge while the males stay on. After the young have fledged, the male begins his migration south and the young make their first migration on their own.

Food

On the breeding grounds, knots eat mostly spiders, arthropods, and larvae obtained by surface pecking, and on the wintering and migratory grounds they eat a variety of hard-shelled prey such as bivalves, gastropods and small crabs that are ingested whole and crushed by a muscular stomach.