{"id":7173,"date":"2024-11-22T19:26:31","date_gmt":"2024-11-22T19:26:31","guid":{"rendered":"https:\/\/wordpress.viu.ca\/biol325\/?p=7173"},"modified":"2024-12-01T21:31:16","modified_gmt":"2024-12-01T21:31:16","slug":"dunlins-the-shorebird-acrobatic","status":"publish","type":"post","link":"https:\/\/wordpress.viu.ca\/biol325\/2024\/11\/22\/dunlins-the-shorebird-acrobatic\/","title":{"rendered":"Dunlins: The Shorebird Acrobatic"},"content":{"rendered":"\n

Eric MacDowell<\/h2>\n\n\n\n

VIU Ornithology, Biol 325<\/h2>\n\n\n\n

Introduction<\/h1>\n\n\n\n

Imagine you are taking the coastal route home on a late November evening. The sun reaching towards the horizon with its golden hands <\/strong>until dusk arrives with a icy breeze. Suddenly, a bright flash of white and a whirlwind of movement in the sky catches your attention. You pull over and look up to see a dense cloud of hundreds of tiny birds all synchronously along the lagoon. You see a number of young adults bunched up in a tight group, all with binoculars up to their eyes. You call out to them,  \u201cWhat are these mesmerizing birds?\u201d<\/p>\n\n\n\n

\u201cThey\u2019re Dunlins!\u201d one of them shouted back, excitedly. <\/strong><\/p>\n\n\n\n

Taxonomy<\/h1>\n\n\n\n

Common name: Dunlin<\/p>\n\n\n\n

Scientific name: Calidris alpina<\/em><\/p>\n\n\n\n

Order Charadriiformes<\/p>\n\n\n\n

Family Scolopacidae<\/p>\n\n\n

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Photo by Laura Erickson<\/figcaption><\/figure>\n<\/div>\n\n\n

Identification<\/h1>\n\n\n\n

The Dunlin is a stout, medium-sized migratory wading birds, commonly found flocking in large numbers in the fall. These birds are similar in size to many other of the sandpipers found across the pacific northwest at 16-22 cm long (Species showcase: Dunlin, 2024; All About Birds, 2024). An adult Dunlin comes in at a whopping 48-76 g, approximately the weight of a mole (U.S. Fish & Wildlife Service, 2024).<\/p>\n\n\n

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Identifying sandpipers can take some time, especially Dunlins. Characteristics that are found in Dunlins like black legs and a long, black, droopy bill that resembles pencil may lead you to think of the Western Sandpiper (Ehrlich, Dobkin, Wheye,1988; All About Birds, 2024). However, Dunlins have darker shades of plumage and are larger size which are small details that may help guide you to identifying Dunlins (Ehrlich, Dobkin, Wheye,1988).<\/p>\n\n\n

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Figure 1. Breeding adult<\/strong><\/figcaption><\/figure>\n<\/div>\n\n\n

During breeding season (spring and summer), these cute sandpipers are easy to spot due to a few characteristic features. Their mottled chestnut brown and black backs, along with copper-coloured caps, are typical of their breeding plumage. Additionally, both male and female Dunlins have black belly patches surrounded by white feathers, which are iconic to their breeding appearance (All About Birds, 2024).<\/p>\n\n\n\n

Dunlin non-breeding plumage is less striking compared to their breeding plumage. In fact, the name Dunlin originated from the an early English word, \u201cdunling,\u201d which means \u201clittle brown one\u201d as reference to the colour of their non-breeding plumage which is quite muted grayish brown, also known as \u201cdun.\u201d (All About Birds 2024).<\/p>\n\n\n

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Figure 2: Non Breeding Dunlin<\/strong><\/figcaption><\/figure>\n<\/div>\n\n\n

Males and females can be quite difficult to differentiate at this time because both sexes have very similar appearances (Malick-Wahls et al., 2024). <\/strong>However, females tend to be larger in size with slightly longer bills  <\/strong>(Malick-Wahls et al 2024; eBird, 2024). <\/strong>Breeding plumage may give a better idea between the two where males generally have whiter or lighter hindnecks but this difference is not always present (Malick-Wahls et al., 2024). <\/strong><\/p>\n\n\n\n

Another distinguishing feature, visible in all plumage types and sexes, is the white underwings which are distinctive in flight. (All about Birds, 2024). It’s truly incredible to see a large flock in flight, with the bright flashes of their underwings as they wheel <\/strong>around the bay.<\/p>\n\n\n\n

Habitat, Migration<\/h1>\n\n\n\n

Since there are six known genera of dunlin and many of them have different migration pattens, I will focus on the North American populations of Dunlin in the genus, Calidris alpina <\/em>(Environment Canada, 1997). These sandpipers breed in subarctic and mid arctic wetlands during the spring and summer but may use sandy beaches, coastal grasslands, and muddy freshwater areas if the preferred environment is not available (Environment Canada, 1997).  By late summer and early fall, breeding has finished, and dunlins stock up on food then independently disperse as juveniles to a large range of locations on the North American coastline (All about Birds, 2024). Interestingly, they tend to stay at higher latitudes when migrating much later in the fall than most shorebirds (Environment Canada, 1997). Wintering locations can vary from as north as the coast of British Columbia and New England to as far south as the Northern Mexico and Florida (All about Birds, 2024). Wintering locations can also change based on a number of factors such as food availability and predators (Environment Canada, 1997). In regard to habitat type during the winter, Dunlins prefer environments such as coastal estuaries, muddy intertidal zones , agricultural lands (Martins, Santos, Palmeirim, Granadeiro, 2013).<\/p>\n\n\n

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Figure 4: Dunlin Migration and Habitat<\/figcaption><\/figure>\n<\/div>\n\n\n

Food and Behaviour<\/h1>\n\n\n\n

While migrating or during their non-breeding season (winter), Dunlins heavily rely on the intertidal zone for food. You may see them getting chased by the tide, running back and forth around low tide feeding areas, probing the mud and sand with their long, curved bill (Koloski, Coulson, Nol, 2016). During the wintering period, their diet consists of organisms such as crustaceans (and their eggs!), mollusks, insects, and marine worms (Canadian Wildlife Service, 2014). In contrast, during breeding season, they feed primarily on flies and mosquito larvae (Canadian Wildlife Service, 2014).<\/p>\n\n\n\n

Murmuration <\/h2>\n\n\n\n

Dunlins are exceptional at flying within a flock. At dusk and while nesting, tight and cohesive flying with up to 500 individuals without a leader helps provide safety in numbers against predators such as the Peregrine falcons, increases and creates a mesmerizing birding experience (Ruiz, Connors, Griffin, Pitelka, 1989; <\/strong>All about Birds, 2024;<\/strong> American Bird Conservancy, 2017). This behaviour is also exhibited in starlings and is called murmuration (Ruiz, Connors, Griffin, Pitelka, 1989; <\/strong>All about Birds, 2024).<\/p>\n\n\n\n

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