Wednesday 19 June 2013

D is for Dunlin

Dunlin (Calidris alpina)


The dunlin is one of our commonest waders in both freshwater and saltwater habitats. It is a callidriid sandpiper, meaning it has the short legs and bill and dumpy body which characterise this group. This, combined with its skittering gait make it frankly adorable. The dunlins diminutive nature is well illustrated by some of its local names; the sea mouse (Lancashire and Dumfries) and the Sand mouse (Westmorland)1.
This small wader is quite distinctive in its bright summer plumage, with golden-brown wings flecked with black “V’s” and a smart black patch on its pale belly. In winter, however it becomes the delicate grey of most wintering sandpipers and is more difficult to distinguish. If you want to confound yourself even further, there are several races of dunlin which visit Britain, each with slightly different markings and body proportions. The race C.a.arctica simply passes through Britain in autumn on migration to West Africa; The race C.a.shinzii breeds here;  whilst the race C.a. alpina overwinters2,3.

Dunlins spend a lot of their time frantically feeding to fuel their high metabolisms, plucking insects, curstaceans and other small invertebrates on or near the surface of sand, mud and shallow water. My wonderful first experience of a dunlin was watching it dodge the surf along a sandy beach in Cornwall, almost at our feet and completely focused on feeding.
When resting they huddle together, often with other waders for safety in numbers and to conserve body heat. Indeed, another local name, ‘the plover’s page’ refers to their habit of following flocks of golden plover Pluvialis apricaria, especially during the breeding season1.
Despite being so common most of the year, the dunlin is very restricted in its breeding habitats, nesting only in sphagnum peat bogs and machair grassland, both rare habitats in the UK which have suffered historical declines due to changes in man’s land use. As a result, the majority of Britain’s dunlins are migrants from mainland Europe.

Perhaps surprisingly for a wader, breeding dunlins ‘sing’, with a scratchy, almost croaking character (recordings of which can be heard here ), and they join in the dawn chorus on their breeding grounds.
So there you have it, a whistlestop tour of the dunlin. A common, unassuming, yet quirky little wader skittering across our shorelines.




References


1-Fransesca Greenoak. (1979) All the Birds of the Air. A. Brown and Sons.

2-Dave Appleton. (no date) Dunlin Calidris alpine. Available from: http://www.gobirding.eu/Photos/Dunlin.php

3- Robert A Robinson. (2013) Profiles of birds occurring in Britain and Ireland-Dunlin Calidris alpina   [Linnaeus, 1758]. Available from: http://blx1.bto.org/birdfacts/results/bob5120.htm

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