Sanderling
Encyclopedia
The Sanderling is a small wader
. It is a circumpolar Arctic
breeder, and is a long-distance migrant
, wintering south to South America
, South Europe
, Africa
, and Australia
. It is highly gregarious in winter, sometimes forming large flocks on coastal mudflats or sandy beaches.
It is somewhat unlike other sandpipers in appearance, which has led to the suggestion that it should be placed into a monotypic
genus Crocethia. A more recent review (Thomas et al., 2004) indicates, however, that the sanderling is a fairly typical "stint
" or small sandpiper and should be separated from the large knots with its closest relatives in a distinct genus.
This bird is similar in size to a Dunlin
, but stouter, with a thick bill. It shows a strong white wingbar in flight, and runs along the sandy beaches it prefers with a characteristic "bicycling" action, stopping frequently to pick small food items. It eats small crab
s and other small invertebrate
s. In spring, birds migrating north from South America consume large numbers of horseshoe crab
eggs in the Delaware Bay
area.
In spring, the birds arrive on the High Arctic breeding grounds (see map), where they lay 3–4 eggs in a ground scrape. On the nesting grounds, these birds mainly eat insect
s and some plant material.
The Sanderling is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
) applies.
. The winter bird
is very pale, almost white apart from a dark shoulder patch. This is the source of the specific name, alba, which is the Latin for "white". Later in the summer, the face and throat become brick-red. The juvenile bird is spangled black and white, and shows much more contrast than the adult.
Sanderling behavior is distinctive, but visually, if the size is misjudged, a breeding plumage sanderling can be mistaken for some varieties of stint
, or a winter plumage sanderling can be mistaken for a Dunlin
or Red Knot
. It can be told from other small wading birds, given good views, by its lack of a hind toe.
, Europe
and Asia
. In North America it breeds in the Canadian Arctic Archipelago
, Nunavut
, Greenland
(and to a lesser extent Alaska
), in Eurasia it breeds Spitsbergen
, and areas of northern Russia from the Taymyr Peninsula
to the New Siberian Islands
. In the northern winter it has a nearly cosmopolitan distribution
across the world's marine coasts. It is a complete migrant
, travelling between 3,000 to 10,000 km from its breeding grounds to its wintering sites. Birds that travel further also arrive later and leave sooner. The majority of adults leave the breeding grounds in July and early August, whereas juvenile birds leave in late August and early September. The northward migration begins in March at the southern end of their winter distribution.
The breeding habitat of the Sanderling is coastal tundra north of 5 °C July isotherm. The species typically chooses nesting sites on dry stony areas near wet areas, from 60 m above sea level to 800 m. During the winter and its migration it is most commonly found on coastal sandy beach
es, but also occurs on tidal
sand flats mud flats and the shores of lakes and rivers. More infrequently it make occur on rocky shores.
buried in the sand in the upper intertidal. In North America this largely consists of the isopods
, Excirolana linguifrons and Excirolana kincaidii, and the mole crab, Emerita analoga
. When the tide is out these crustacean
s live in burrows some way beneath the surface. When the tide comes in, they move into the upper layers of sand so as to be able to feed on the plankton
and detritus
that washes over them with each wave. They then burrow rapidly down again as the water retreats. They leave no marks on the surface so the sanderlings hunt for them by plunging their beaks into the sand at random, consuming whatever they find. Their bills can only penetrate two or three centimetres and as the water swirls around and retreats, the sand is softer and this makes it easier for the birds' beaks to penetrate further. In the spring, when much breeding activity is taking place in the benthic
community, there may be as many as 4000 invertebrates per square metre, but their average size is smaller than later in the year. The birds appear to rush madly around at the edge of the surf but in reality they are maximising their chances of catching as many prey animals as possible when they are at their most vulnerable near the surface.
, with the male aggressively defending its territory. They may either form monogamous pairs
or polyandrous (one female and two male) pairings.
Wader
Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...
. It is a circumpolar Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
breeder, and is a long-distance migrant
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, wintering south to South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, South Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It is highly gregarious in winter, sometimes forming large flocks on coastal mudflats or sandy beaches.
It is somewhat unlike other sandpipers in appearance, which has led to the suggestion that it should be placed into a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus Crocethia. A more recent review (Thomas et al., 2004) indicates, however, that the sanderling is a fairly typical "stint
Stint
A stint is one of several very small waders in the paraphyletic "Calidris" assemblage - often separated in Erolia -, which in North America are known as peeps...
" or small sandpiper and should be separated from the large knots with its closest relatives in a distinct genus.
This bird is similar in size to a Dunlin
Dunlin
The Dunlin, Calidris alpina, is a small wader, sometimes separated with the other "stints" in Erolia. 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...
, but stouter, with a thick bill. It shows a strong white wingbar in flight, and runs along the sandy beaches it prefers with a characteristic "bicycling" action, stopping frequently to pick small food items. It eats small crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s and other small invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. In spring, birds migrating north from South America consume large numbers of horseshoe crab
Horseshoe crab
The Atlantic horseshoe crab, Limulus polyphemus, is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs. Horseshoe crabs are most commonly found in the Gulf of Mexico and along the northern Atlantic coast of North America...
eggs in the Delaware Bay
Delaware Bay
Delaware Bay is a major estuary outlet of the Delaware River on the Northeast seaboard of the United States whose fresh water mixes for many miles with the waters of the Atlantic Ocean. It is in area. The bay is bordered by the State of New Jersey and the State of Delaware...
area.
In spring, the birds arrive on the High Arctic breeding grounds (see map), where they lay 3–4 eggs in a ground scrape. On the nesting grounds, these birds mainly eat insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and some plant material.
The Sanderling is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
AEWA
The Agreement on the Conservation of African-Eurasian Migratory Waterbirds is the largest of its kind developed so far under the Bonn Convention. It was concluded on 16 June 1995 at The Hague, the Netherlands and entered into force on 1 November 1999 after the required number of at least fourteen...
) applies.
Description
The Sanderling is a small plump sandpiper, 18–20 cm in length. Its weight ranges from 40-100 gGram
The gram is a metric system unit of mass....
. The winter bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
is very pale, almost white apart from a dark shoulder patch. This is the source of the specific name, alba, which is the Latin for "white". Later in the summer, the face and throat become brick-red. The juvenile bird is spangled black and white, and shows much more contrast than the adult.
Sanderling behavior is distinctive, but visually, if the size is misjudged, a breeding plumage sanderling can be mistaken for some varieties of stint
Stint
A stint is one of several very small waders in the paraphyletic "Calidris" assemblage - often separated in Erolia -, which in North America are known as peeps...
, or a winter plumage sanderling can be mistaken for a Dunlin
Dunlin
The Dunlin, Calidris alpina, is a small wader, sometimes separated with the other "stints" in Erolia. 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...
or Red Knot
Red Knot
The Red Knot, Calidris canutus , is a medium sized shorebird which breeds in tundra and the Arctic Cordillera in the far north of Canada, Europe, and Russia. It is a large member of the Calidris sandpipers, second only to the Great Knot...
. It can be told from other small wading birds, given good views, by its lack of a hind toe.
Distribution, habitat and migration
The Sanderling breeds in the High Arctic areas of North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. In North America it breeds in the Canadian Arctic Archipelago
Canadian Arctic Archipelago
The Canadian Arctic Archipelago, also known as the Arctic Archipelago, is a Canadian archipelago north of the Canadian mainland in the Arctic...
, Nunavut
Nunavut
Nunavut is the largest and newest federal territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999, via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries had been established in 1993...
, Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
(and to a lesser extent Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
), in Eurasia it breeds Spitsbergen
Spitsbergen
Spitsbergen is the largest and only permanently populated island of the Svalbard archipelago in Norway. Constituting the western-most bulk of the archipelago, it borders the Arctic Ocean, the Norwegian Sea and the Greenland Sea...
, and areas of northern Russia from the Taymyr Peninsula
Taymyr Peninsula
The Taymyr Peninsula is a peninsula in the Far North of Russia, in the Siberian Federal District, that forms the northernmost part of mainland Eurasia and Asia...
to the New Siberian Islands
New Siberian Islands
The New Siberian Islands are an archipelago, located to the North of the East Siberian coast between the Laptev Sea and the East Siberian Sea north of the Sakha Republic....
. In the northern winter it has a nearly cosmopolitan distribution
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
across the world's marine coasts. It is a complete migrant
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, travelling between 3,000 to 10,000 km from its breeding grounds to its wintering sites. Birds that travel further also arrive later and leave sooner. The majority of adults leave the breeding grounds in July and early August, whereas juvenile birds leave in late August and early September. The northward migration begins in March at the southern end of their winter distribution.
The breeding habitat of the Sanderling is coastal tundra north of 5 °C July isotherm. The species typically chooses nesting sites on dry stony areas near wet areas, from 60 m above sea level to 800 m. During the winter and its migration it is most commonly found on coastal sandy beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...
es, but also occurs on tidal
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
sand flats mud flats and the shores of lakes and rivers. More infrequently it make occur on rocky shores.
Feeding behaviour
Sanderlings feed on invertebrate preyPredation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
buried in the sand in the upper intertidal. In North America this largely consists of the isopods
Isopoda
Isopods are an order of peracarid crustaceans, including familiar animals such as woodlice and pill bugs. The name Isopoda derives from the Greek roots and...
, Excirolana linguifrons and Excirolana kincaidii, and the mole crab, Emerita analoga
Emerita analoga
Emerita analoga, the Pacific sand crab or Pacific mole crab, is a species of small, sand-burrowing decapod crustacean found living in the sand along the temperate western coasts of America. It is found on exposed sandy beaches in the swash region of the intertidal zone.-Description:The Pacific sand...
. When the tide is out these crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s live in burrows some way beneath the surface. When the tide comes in, they move into the upper layers of sand so as to be able to feed on the plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
and detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
that washes over them with each wave. They then burrow rapidly down again as the water retreats. They leave no marks on the surface so the sanderlings hunt for them by plunging their beaks into the sand at random, consuming whatever they find. Their bills can only penetrate two or three centimetres and as the water swirls around and retreats, the sand is softer and this makes it easier for the birds' beaks to penetrate further. In the spring, when much breeding activity is taking place in the benthic
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
community, there may be as many as 4000 invertebrates per square metre, but their average size is smaller than later in the year. The birds appear to rush madly around at the edge of the surf but in reality they are maximising their chances of catching as many prey animals as possible when they are at their most vulnerable near the surface.
Breeding behaviour
Sanderlings are territorialTerritory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
, with the male aggressively defending its territory. They may either form monogamous pairs
Monogamy
Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
or polyandrous (one female and two male) pairings.
External links
- Sanderling videos, photos & sounds on the Internet Bird Collection
- Sanderling Species Account — Cornell Lab of Ornithology
- Sanderling Calidris alba — USGS Patuxent Bird Identification InfoCenter
- Sanderling Information — South Dakota Birds and Birding