Dunlin

The dunlin (Calidris alpina) is a small wader, sometimes separated with the other "stints" in Erolia. The English name is a dialect form of "dunling", first recorded in 1531–2. It derives from dun, "dull brown", with the suffix -ling, meaning a person or thing with the given quality.[2] The genus name is from Ancient Greek kalidris or skalidris, a term used by Aristotle for some grey-coloured waterside birds. The specific alpina is from Latin and means "of high mountains", in this case referring to the Alps.[3]

For other uses, see Dunlin (disambiguation).

Dunlin
Juvenile, Farmoor Reservoir, Oxfordshire
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Scolopacidae
Genus: Calidris
Species:
C. alpina
Binomial name
Calidris alpina
Range of C. alpina
  Breeding
  Resident
  Non-breeding
  Passage
  Vagrant (seasonality uncertain)
Synonyms
  • Tringa alpina Linnaeus, 1758
  • Erolia alpina (Linnaeus, 1758)
  • Pelidna alpina (Linnaeus, 1758)

It is a circumpolar breeder in Arctic or subarctic regions. Birds that breed in northern Europe and Asia are long-distance migrants, wintering south to Africa, southeast Asia and the Middle East. Birds that breed in Alaska and the Canadian Arctic migrate short distances to the Pacific and Atlantic coasts of North America, although those nesting in northern Alaska overwinter in Asia. Many dunlins winter along the Iberian south coast.

Description
Adult dunlin in winter plumage, Sandy Hook, New Jersey, USA.
Dunlin in late September at Easton Bavents, Suffolk, UK.

Measurements:[4]

  • Length: 6.3-8.7 in (16-22 cm)
  • Weight: 1.7-2.7 oz (48.7-75.9 g)
  • Wingspan: 14.2-15.0 in (36-38 cm)

An adult dunlin in breeding plumage shows the distinctive black belly which no other similar-sized wader possesses. The winter dunlin is basically grey above and white below. Juveniles are brown above with two whitish "V" shapes on the back. They usually have black marks on the flanks or belly and show a strong white wingbar in flight.

The legs and slightly decurved bill are black. There are a number of subspecies differing mainly in the extent of rufous colouration in the breeding plumage and the bill length. Bill length varies between sexes, the females having longer bills than the males.

On the tip of the Dunlin's bill is a soft covering that fills with blood and with many nerve endings, forming a sensitive probe that is used to locate invertebrate prey in mud and sand. Although the bill can look sharp-pointed in dead specimens, in life it is blunt.[5]

Subspecies
Distribution of subspecies, migration routes, and major European wintering sites

Nesting
Eggs, Collection Museum Wiesbaden, Germany
Calidris alpina schinzii - MHNT

The nest is a shallow scrape on the ground lined with vegetation, into which typically four eggs are laid and incubated by the male and female parents. Chicks are precocial, however are brooded during early development. They start to fly at approximately three weeks of age. The majority of brood care is provided by the male, as the female deserts the brood and often leaves the breeding area.

The call is a typical sandpiper "peep", and the display song a harsh trill.

The dunlin is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

Apparent hybrids between this species and the white-rumped sandpiper as well as with the purple sandpiper have been reported from the Atlantic coasts of North America[6][7] and Europe,[8] respectively.

Behaviour

The dunlin is highly gregarious in winter, sometimes forming large flocks on coastal mudflats or sandy beaches. Large numbers can often be seen swirling in synchronized flight on stop-overs during migration or on their winter habitat.

This bird is one of the most common waders throughout its breeding and wintering ranges, and it is the species with which other waders tend to be compared. At 17–21 cm (6.7–8.3 in) length and with a 32–36 cm (13–14 in) wingspan, it is similar in size to a common starling, but stouter, with a thicker bill.

The dunlin moves along the coastal mudflat beaches it prefers with a characteristic "sewing machine" feeding action, methodically picking small food items. Insects form the main part of the dunlin's diet on the nesting grounds; it eats molluscs, worms and crustaceans in coastal areas.

On the East coast of England
Calidris alpina. Ystad/Sweden 2015.

Dunlin are small migratory waders, however they show strong philopatry with individuals of the Southern Dunlin (Calidris alpina schinzii) in Sweden and Finland returning to, or very close to, their natal patches. Habitat fragmentation has reduced the availability of habitat patches to these birds through reducing patch size and increasing patch isolation. This reduced connectivity between patches has reduced the movements of Dunlin leaving them more susceptible to inbreeding in these locations. Future management for the conservation of Southern Dunlin should include increasing the connectivity between habitat patches.[9]

References
  1. BirdLife International (2012). "Calidris alpina". IUCN Red List of Threatened Species. 2012. Retrieved 26 November 2013.CS1 maint: ref=harv (link)
  2. "Dunlin". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 42, 84. ISBN 978-1-4081-2501-4.
  4. "Dunlin Identification, All About Birds, Cornell Lab of Ornithology". www.allaboutbirds.org. Retrieved 2020-09-27.
  5. Kaiser, Gary W. (2007). The Inner Bird: Anatomy and Evolution. UBC Press. p. 24. ISBN 978-0-7748-1344-0.
  6. McLaughlin, K.A.; Wormington, A. (2000). "An apparent Dunlin × White-rumped Sandpiper hybrid". Ontario Birds. 18 (1): 8–12.
  7. Wilson, Angus. "A putative hybrid white-rumped sandpiper × dunlin from the east coast of the USA". Ocean Wanderers. Retrieved 11 October 2006.
  8. Millington, Richard (1994). "A mystery Calidris at Cley". Birding World. 7 (2): 61–63. Archived from the original on 17 June 2004.
  9. Pakanen, V.-M.; Koivula, K.; Flodin, L.-Å.; Grissot, A.; Hagstedt, R.; Larsson, M.; Pauliny, A.; Rönkä, N.; Blomqvist, D. (2017). "Between-patch natal dispersal declines with increasing natal patch size and distance to other patches in the endangered Southern Dunlin Calidris alpina schinzii". Ibis. 159 (3): 611–622. doi:10.1111/ibi.12463.


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