Calidris maritima

Calidris maritima

The violet sandpiper (Calidris maritima, Brünnich 1764) is a bird belonging to the Scolopacidae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain;
Kingdom Animalia;
Phylum Chordata;
Subphylum Vertebrata;
Aves class;
Order Charadriiformes;
Suborder Piarist;
Scolopacidae family;
Genus Calidris;
C. maritima species.
The term is basonym:
– Tringa maritima Brünnich, 1764.
The terms are synonyms:
– Arquatella maritima (Brünnich, 1764);
– Erolia maritima (Brünnich, 1764);
– Pelidna maritima (Brünnich, 1764);
– Tringa striata Linnaeus.
Within this species, the following four subspecies are recognised:
– Calidris maritima subsp. belcheri Engelmoer & Roselaar, 1998;
– Calidris maritima subsp. littoralis (C.L.Brehm, 1831);
– Calidris maritima subsp. maritima (Brunnich, 1764);
– Calidris maritima subsp. groenlandica.

Geographic Distribution and Habitat –
The Calidris maritima is a bird widespread in a large range which includes: central, western and northern Europe, including Italy, Greenland, Canada and the eastern United States.
It is in step in Eastern Europe, Switzerland, Morocco, Cape Verde, Libya, Malta and Kazakhstan.
Its breeding range extends from the Arctic Islands of northern Canada eastward to Greenland, Iceland, Svalbard and northern Scandinavia to western Siberia and the Taymyr Peninsula. In the high arctic Calidris maritima nests low in the tundra, sometimes far from the coast, but in the subarctic regions of Sweden and Norway it nests on barren mountainsides near the frozen ground line. Birds that breed in high latitudes migrate south and spend the winter on rocky shores on both sides of the North Atlantic. They winter along the North American coast to South Carolina and on the eastern Atlantic coast to France and northern Iberia.
Birds that winter in northern Scotland and southwest Ireland migrate to Canada (Baffin Island and Devon Island) to breed.

Description –
The Calidris maritima is a bird which in the adult stage is recognized by its short light yellow-brown legs and a medium thin dark beak with a yellow base, with males and females being indistinguishable from each other in nature.
The juveniles are quite similar to the adults in wedding dress but with beak at the base and yellow – orange legs.
The dimensions in length are 20-22 cm, with a wingspan of 42-46 cm and a weight ranging between 50 and 105 g.
The body is dark above with a slight purplish sheen and mostly white below.
In summer dress they have brown upperparts with white hems on the coverts and black or orange-fawn mottling. The vertex is orange – fawn with thin blackish streaks; nape and sides of head and throat fawn-light ocher with fine blackish streaks behind the eye and a black streak between the eye and dark brown beak.
The chest is fawn – light ocher with thin blackish streaks and fades with this coloration on the white background of the abdomen and belly.
The tail has a blackish streak in the center and is brown on the sides.
The wings, in the upper part, are dark brown tending to blackish towards the ends and with a thin but clear white band.
In winter dress, adults have brown upper parts and head with dark streaks on the wings.
The chest is also brown with darker mottling fading towards the white of the abdomen and belly.
Between the eye and the beak there is a blackish streak and a white speck at the base of the beak. The latter takes on a strong orange ocher color at the base which fades to blackish towards the tip.

Biology –
The breeding habitat of Calidris maritima is the northern tundra of the Arctic islands in Canada and the coastal areas of Greenland and north-western Europe. They can reproduce at one year of age.
The male makes several scratches on the ground; the female chooses one and lays 3 or 4 eggs. These are olive in color with brown spots and measure approximately 37mm × 26mm.
The male takes primary responsibility for incubating the eggs which hatch in 21-22 days.
After hatching, the chicks are covered in thick hair. The upperparts have black and cinnamon spots with white spots; the underparts are mostly white.
Usually only the male takes care of the chicks which can feed themselves.
The maximum age of this bird recorded from ring recovery data in Europe is 20 years and 9 months for a bird recovered in Sweden.

Ecological role –
The Calidris maritima is a bird linked mainly to a habitat and usually, outside the reproductive season, it settles on rocks where it looks for worms and on the twisted masses of maritime oak and algae where it finds crustaceans, mussels discovered by the tide, also on piers and breakwater and remains “invisible” until it moves, but it is still a sociable bird and can be approached quite easily.
If a wave surprises it while it is on a rock to feed, it remains in place letting itself be lifted by the water to then fall back and return to its place as if nothing had happened.
This bird is never seen on beaches or mudflats. In flight it is recognized by a narrow but evident white wing bar, however it has a more compact structure than the other waders. It winters in small flocks on rocky coasts and islets.
As far as its state of conservation is concerned, it is a species with a very vast range and with a very numerous, albeit decreasing, population.
The International Union for Conservation of Nature (IUCN) has rated the threat to the species as “of least concern”.
It is one of the species to which the Agreement on the Conservation of Migratory Waterbirds of Africa and Eurasia (AEWA) applies.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– C.Battisti, D. Taffon, F. Giucca, 2008. Atlas of nesting birds, Gangemi Editore, Rome.
– L. Svensson, K.Mullarney, D. Zetterstrom, 1999. Guide to Birds of Europe, North Africa and the Near East, Harper Collins Publisher, UK.

Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/253680394/original.jpg