MIGRATION MIRACLES: THE SANDERLING

The Sanderling Calidris alba is a small long-distance migratory shorebird of approximately 20 cm height and a wingspan of 40 cm which inhabits coastal sandy beaches, lagoons, estuaries and mixed shorelines.

They have a black bill and legs with a pale colored body outside of the breeding season, which gives them their latin name alba (white).

The genus name Calidris comes from the ancient Greek kalidris used by Aristotle to describe some grey-coloured waterside birds.

A trip of 18,000 kilometers twice per year

Sanderlings are often seen along the coast in small flocks where they run up and down the beach or on mudflats feeding on insect larvae, small bivalves, amphipods, isopods, gastropods and other small marine invertebrates.

Their body mass varies greatly throughout the year due to their migratory effort. Thus, Sanderlings can weigh from 40 to 100 g and have an average weight of approximately 55g.

Sanderlings breed throughout the far north Holarctic (Canadian Arctic, Greenland and Siberia) with the population migrating to southern Africa originating in Greenland and Siberia. Sanderlings are summer visitors which arrive in southern Africa by the beginning of September and leave around mid April.

This is a trip of at least 18,000 kilometers twice per year.

The map shows all the locations where the Sanderlings observed in Namibia by Mark Boorman have been spotted across the globe by other observers. This information has been extracted from a database containing more than 1100 observations of 94 individually marked birds.

Clockwise loop migration

The observations reported suggest that Sanderlings visiting Namibia travel along West Africa using the East Atlantic Flyway and breed mostly in Greenland.

However, there are studies that show that an unknown amount of the Sanderlings spotted in southern Africa breed in Siberia and travel down through Asia and east Africa to mix with those of Nearctic distribution and then use the East Atlantic Flyway to reach Siberia, suggesting a clockwise loop migration.

A special visitor to Namibia

A special visitor to Namibia is W1YYYW. Ringed on 17-07-2008 in Zackenberg, Greenland, this bird has been observed for 11 consecutive seasons at Walvis Bay, with the latest sighting being 06-03-2019.

In the interim she has been recorded back on the breeding grounds in Greenland several times. Additional sightings have also been made at a stopover area in Holland on her trips south. A single sighting of this bird in France has also been recorded.

These long-distance migratory birds arrive in Namibia in September and leave around end of March with the last birds seen mid-April. The birds visiting Namibia reach the breeding grounds in Greenland from the end of May and leave at the end of July, beginning of August.

This means that it takes approximately six weeks to two months for a bird to travel between the southern and the northern hemisphere.

Sanderlings are Ecological Indicators

Sanderlings are indicators of the ecological state of their various habitats.

The pollution and the destruction of the habitats required as feeding and resting areas together with the recreational activities and an intensive human coastal use, are all threats to this species.

Human disturbances alter the feeding and resting habits which are crucial to reach the healthy physical status required during the long migration.

Thus, our country has a high responsibility for the conservation of Sanderlings as with many other migratory birds.

Flock of Sanderlings on the Skeleton Coast, Namibia. Photo: Ruben Portas

Namibia counts more than 1% of the global Sanderling population!

Namibia is Very Important for Sanderlings

Sanderlings show high fidelity to their non-breeding and stopover sites during migration. This makes them vulnerable to alterations in those crucial foraging and resting areas.

In Namibia, wetland surveys have shown counts of more than 1% of the total Sanderling population, which is one of the criteria qualifying the areas used by these birds as being IBAs (Important Bird Areas). Thus, our country has a high responsibility for the conservation of Sanderlings as with many other migratory birds.

Namibia has a high responsibility for the conservation of Sanderlings

Sanderling tagged with colored rings (B3RYBW) in Zackenberg (Greenland) in July 2013 and photographed in January 2014 on the Skeleton Coast. Photo: Ruben Portas