Monday, 10 February 2014

Week 38: Dunlin (‘Calidris alpina’)

The Dunlin was @SpeciesofUK from 14th to 20th October, 2013.

Dunlins are waders that form massive winter flocks in the UK. They are known for the black bellies they develop in their distinctive breeding plumage.

[Source: Flickr Creative Commons © talis qualis]

Dunlins are one of the UK’s most common waders.

Dunlins are found right across the northern hemisphere, from North America to Russia and China, to the African, Mediterranean and Arabian coasts.[1]

Dunlins breed in UK uplands from April to July. During this time, they are found in their greatest numbers in the Western and Northern Isles, the Flow Country (in the far north of Scotland) and the Pennines.[2]

Dunlins in the Western Isles
[Source: Flickr Creative Commons © IrenicRhonda]

Outside of the non-breeding season dunlins prefer estuarine mudflats, or failing that any freshwater and brackish wetlands.[3]

Dunlins Love the Mud!
[Source: Flickr Creative Commons © Valter Jacinto]

A group of dunlins are known as a 'flight', a ‘fling’ and a ‘trip’.[4]

Dunlins have striking breeding plumage.

The dunlin has a slightly down-curved bill, which (along with the legs) is black. The females have slightly longer bills than males.[5].

Slightly Down-curved Bill
[Source: Flickr Creative Commons © jvverde]

In flight it has white underwings, a white line down the middle of the upperwing, and white on either side of its rump and tail. The white underwings are especially distinctive in flight.[6]

White Lines on Upperwing
[Source: Flickr Creative Commons © jvverde]

White Underwings
[Source: Flickr Creative Commons © prorallypix]

In its breeding plumage, the dunlin has a distinctive black belly patch and reddish back and cap. The black belly in particular distinguishes it from all other similar-sized waders.[7]

Dunlin in Breeding Plumage
[Source: Flickr Creative Commons © mikebaird]

In winter, dunlin plumage becomes very dull, fading to greyish above and white below.

Dunlins in Winter Plumage
[Source: Flickr Creative Commons © Dendroica cerulea]

Juvenile dunlins are brown above with brownish black splotches on the belly.[8]

Juvenile Dunlin
[Source: Flickr Creative Commons © jvverde]

The call of the dunlin is a "peep", and its display song is a harsh trill.[9]

Dunlins are active both day and night.

Dunlins feed at night as well as during the day. They feed by probing and jabbing with their long bill in the substrate.[10]

Dunlins Feeding
[Source: Flickr Creative Commons © Len Blumin]

The dunlin eats adult and larval insects, spiders, mites, earthworms, snails, slugs and plant matter (usually seeds). On the coast, it also eats polychaete worms, crustaceans, bivalves, and occasionally small fish.[11]

Dunlins Feeding at Low Tide
[Source: Flickr Creative Commons © Seuss]

And here is a video of dunlins feeding alongside western sandpipers.

Male dunlins work hard to court potential mates.

Male dunlins arrive at the breeding grounds first. When females arrive, the males perform display flights - short glides interrupted by rapid flutters.[12]

The male dunlin then make several scrapes in the ground. The female chooses one and finishes it off to make the nest.[13]

Romantic Stroll on the Beach
[Source: Flickr Creative Commons © Sergey Gabdurakhmanov]

A dunlin nest is a scrape or shallow depression in the ground, concealed in vegetation and sometimes in a tuft or tussock (and thus raised slightly off the ground).[14]

The dunlin usually lays four eggs, which are incubated for twenty to twenty-two. The young leave the nest shortly after hatching and find their own food.[15]

Dance of the dunlins.

Outside of the breeding season, the dunlin is very gregarious. It forms groups of up to hundreds of thousands at the wintering grounds.[16]

Gregarious Dunlins
[Source: Flickr Creative Commons © hjhipster]

Here is a wonderful video of dunlins flocking at their wintering grounds ‘murmurating’.

Strange but true…

The male dunlin is the more caring of the parents. The female usually abandons the family group within a week of hatching. The male generally stays with the young until they are close to fledging, typically about nineteen days.[17]


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