Calidrid
Encyclopedia
The calidrids or typical waders are a group of Arctic
-breeding, strongly migratory
wading
bird
s. These birds form huge mixed flocks on coasts and estuaries in winter. They are the typical "sandpipers", small to medium-sized, long-winged and relatively short-billed.
Their bills
have sensitive tips which contain numerous Corpuscles of Herbst
. This enables the birds to locate buried prey items, which they typically seek with restless running and probing.
As the common name "sandpiper" is shared by some calidrids with more distantly related birds such as the Actitis
species, the term stint
is preferred in Britain for the smaller species of this group.
, and if the calidrids were to be considered one or two tribe
s Calidriini and/or Arenariini, and/or subfamily Eroliinae, the turnstones would be included in it. There exists a fossil
bone, a distal piece of tarsometatarsus
found in the Edson Beds of Sherman County, Kansas
. Dating from the mid-Blancan
some 4-3 million years ago, it appears to be from a calidriid somewhat similar to a Pectoral Sandpiper
, but has some traits reminiscent of turnstones. Depending on which traits are apomorphic and plesiomorphic, it may be an ancestral representative of either lineage. It might also belong to some distinct prehistoric genus, as true calidriid sandpipers seem to have been present earlier (see below).
The interrelationships of the calidrid group are not altogether well resolved. Several former genera have been included in Calidris, such as the Stilt Sandpiper
(previously Micropalama himantopus), but the new placement was also not entirely satisfactory. It was suggested, for example, that the Sanderling
should be placed into a monotypic
genus Crocethia, and the other small Calidris species separated as Erolia. Alternatively, it was suggested that the monotypic Aphriza, Limicola and Eurynorhynchus be also merged into Calidris.
A comprehensive analysis in 2004 –, based on newly available DNA sequence
data – indicated that the extended Calidris is indeed paraphyletic (or polyphyletic if all calidrids are combined in it), but found the present DNA sequence
data insufficient to resolve the relationships of some more unusual taxa such as the Curlew Sandpiper
. In addition, it is known that the calidriid lineages are able to hybridize to a considerable extent
and in the past, this was probably even more frequent and more hybrids would have been viable; therefore studies based on mtDNA data alone can be unreliable.
Still, three groups of close relatives emerge:
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Other calidrids (all at some time placed in Calidris too)
As mentioned above, there exists some material of birds essentially identical to calidriid sandpipers from before the Pleistocene
. An undescribed species is known from the Early Miocene
of Dolnice (Czechia). Tringa gracilis (Early Miocene of WC Europe) and Tringa minor (= Totanus minor, Erolia ennouchii) from the Middle Miocene of Grive-Saint-Alban (France) are scolopacids of rather uncertain affiliations; they might be charadriids.
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...
-breeding, strongly migratory
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...
wading
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...
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...
s. These birds form huge mixed flocks on coasts and estuaries in winter. They are the typical "sandpipers", small to medium-sized, long-winged and relatively short-billed.
Their bills
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
have sensitive tips which contain numerous Corpuscles of Herbst
Corpuscles of Herbst
The Corpuscles of Herbst or Herbst corpuscles are a nerve-ending similar to the Pacinian corpuscle, in the mucous membrane of the tongue, in pits on the beak and in other parts of the bodies of birds...
. This enables the birds to locate buried prey items, which they typically seek with restless running and probing.
As the common name "sandpiper" is shared by some calidrids with more distantly related birds such as the Actitis
Actitis
Actitis is a small genus of waders, comprising just two very similar bird species:* Common Sandpiper, Actitis hypoleucos, of Eurasia* Spotted Sandpiper, Actitis macularia of North America...
species, the term 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...
is preferred in Britain for the smaller species of this group.
Systematics and taxonomy
The calidrids' closest relatives are the two species of turnstoneTurnstone
Turnstones are the bird species in the genus Arenaria in the family Scolopacidae. They are closely related to calidrid sandpipers and might be considered members of the tribe Calidriini....
, and if the calidrids were to be considered one or two tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
s Calidriini and/or Arenariini, and/or subfamily Eroliinae, the turnstones would be included in it. There exists a fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
bone, a distal piece of tarsometatarsus
Tarsometatarsus
The tarsometatarsus is a bone that is found in the lower leg of certain tetrapods, namely birds.It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsal and metatarsal bones...
found in the Edson Beds of Sherman County, Kansas
Sherman County, Kansas
Sherman County is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 6,010...
. Dating from the mid-Blancan
Blancan
The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 4,750,000 to 1,808,000 years BP, a period of .. It is usually considered to start in the early-mid Pliocene epoch and end...
some 4-3 million years ago, it appears to be from a calidriid somewhat similar to a Pectoral Sandpiper
Pectoral Sandpiper
The Pectoral Sandpiper, Calidris melanotos, is a small wader. It is sometimes separated with the "stint" sandpipers in Erolia. This may or may not represent a good monophyletic group, depending on the placement of the phylogenetically enigmatic Curlew Sandpiper , the type species of Erolia...
, but has some traits reminiscent of turnstones. Depending on which traits are apomorphic and plesiomorphic, it may be an ancestral representative of either lineage. It might also belong to some distinct prehistoric genus, as true calidriid sandpipers seem to have been present earlier (see below).
The interrelationships of the calidrid group are not altogether well resolved. Several former genera have been included in Calidris, such as the Stilt Sandpiper
Stilt Sandpiper
The Stilt Sandpiper, Calidris himantopus or Micropalama himantopus, is a small shorebird; it bears some resemblance to the smaller calidrid sandpipers or "stints". DNA sequence information is incapable of determining whether it should be placed in Calidris or in the monotypic genus Micropalama...
(previously Micropalama himantopus), but the new placement was also not entirely satisfactory. It was suggested, for example, that the Sanderling
Sanderling
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...
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, and the other small Calidris species separated as Erolia. Alternatively, it was suggested that the monotypic Aphriza, Limicola and Eurynorhynchus be also merged into Calidris.
A comprehensive analysis in 2004 –, based on newly available DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data – indicated that the extended Calidris is indeed paraphyletic (or polyphyletic if all calidrids are combined in it), but found the present DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data insufficient to resolve the relationships of some more unusual taxa such as the Curlew Sandpiper
Curlew Sandpiper
The Curlew Sandpiper is a small wader that breeds on the tundra of Arctic Siberia. It is strongly migratory, wintering mainly in Africa, but also in south and southeast Asia and in Australasia...
. In addition, it is known that the calidriid lineages are able to hybridize to a considerable extent
Hybridisation in shorebirds
Hybridisation in shorebirds has been proven on only a small number of occasions; however, many individual shorebirds have been recorded by birdwatchers worldwide which do not fit the characters of known species. Many of these have been suspected of being hybrids. In several cases, shorebird hybrids...
and in the past, this was probably even more frequent and more hybrids would have been viable; therefore studies based on mtDNA data alone can be unreliable.
Still, three groups of close relatives emerge:
- The largest contains the smaller species, including the Sanderling, and probably also the Buff-breasted SandpiperBuff-breasted SandpiperThe Buff-breasted Sandpiper, Tryngites subruficollis, is a small shorebird. It is a calidrid sandpipers and currently considered to be the only member of the genus Tryngites. Indeed, it probably belongs in the genus Calidris itself, or more precisely with the small species thereof which should be...
. If it is considered a distinct genus, the name Ereunetes would apply, first published in 1811. The Curlew SandpiperCurlew SandpiperThe Curlew Sandpiper is a small wader that breeds on the tundra of Arctic Siberia. It is strongly migratory, wintering mainly in Africa, but also in south and southeast Asia and in Australasia...
might also belong here; it is the type speciesType speciesIn biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of Erolia, first published in 1816. - The genus Calidris sensu stricto contains the knots and the surfbird.
- Another small group contains somewhat aberrant species, namely the Ruff, the Broad-billed SandpiperBroad-billed SandpiperThe Broad-billed Sandpiper is a small wading bird. It is the only member of the genus Limicola; some have proposed that it should be placed in the genus Erolia with the "stint" sandpipers, but more recent research suggests that it is should rather go into the genus Philomachus with the ruff and...
, and the Sharp-tailed SandpiperSharp-tailed SandpiperThe Sharp-tailed Sandpiper, Calidris acuminata is a small wader.- Taxonomy :More recently, a review of new data has indicated that this bird should perhaps better be placed into the genus Philomachus- as P...
, which would use the name Philomachus.
Genera and species
The species, according to updated / traditional taxonomy, are as follows:- Genus Calidris sensu stricto - knots
- Great KnotGreat KnotThe Great Knot, Calidris tenuirostris, is a small wader. It is the largest of the calidrid species.Their breeding habitat is tundra in northeast Siberia. They nest on the ground laying about four eggs in a ground scrape. They are strongly migratory wintering on coasts in southern Asia through to...
, Calidris tenuirostris - Red KnotRed KnotThe 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...
, Calidris canutus
- Great Knot
Other calidrids (all at some time placed in Calidris too)
- Genus N.N. (Ereunetes?) - stintStintA 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...
s- Semipalmated SandpiperSemipalmated SandpiperThe Semipalmated Sandpiper, Calidris pusilla, is a very small shorebird. It is sometimes separated with other "stints" in Erolia but although these apparently form a monophyletic group, the present species' old genus Ereunetes had been proposed before Erolia.Adults have black legs and a short stout...
, "Calidris" pusilla or Ereunetes pusillus - Little StintLittle StintThe Little Stint, Calidris minuta , is a very small wader. It breeds in arctic Europe and Asia, and is a long-distance migrant, wintering south to Africa and south Asia...
, "Calidris" minuta - Least SandpiperLeast SandpiperThe Least Sandpiper is the smallest shorebird.This species has greenish legs and a short thin dark bill. Breeding adults are brown with dark brown streaks on top and white underneath. They have a light line above the eye and a dark crown. In winter, Least Sandpipers are grey above...
, "Calidris" minutilla - White-rumped SandpiperWhite-rumped SandpiperThe White-rumped Sandpiper is a small shorebird.Adults have black legs and a small thin dark bill. The body is dark brown on top and mainly white underneath, with brown streaks on the breast and a white rump. They have a white stripe over their eyes. This bird shows long wings in flight. In winter...
, "Calidris" fuscicollis - Baird's SandpiperBaird's SandpiperThe Baird's Sandpiper is a small shorebird. It is among those calidrids sometimes separated in Erolia.Adults have black legs and a short thin dark bill. They are dark brown on top and mainly white underneath with a black patch on the rump. The head and breast are light brown with dark streaks. In...
, "Calidris" bairdii - DunlinDunlinThe 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...
, "Calidris" alpina - Red-necked StintRed-necked StintThe Red-necked Stint is a small migratory wader.- Description :These birds are among the smallest of waders, very similar to the Little Stint, Calidris minuta, with which they were once considered conspecific...
, "Calidris" ruficollis - Long-toed StintLong-toed StintThe Long-toed Stint, Calidris or Erolia subminuta, is a small wader bird. It breeds across northern Asia and is strongly migratory, wintering in south and south east Asia and Australasia...
, "Calidris" subminuta - Pectoral SandpiperPectoral SandpiperThe Pectoral Sandpiper, Calidris melanotos, is a small wader. It is sometimes separated with the "stint" sandpipers in Erolia. This may or may not represent a good monophyletic group, depending on the placement of the phylogenetically enigmatic Curlew Sandpiper , the type species of Erolia...
, "Calidris" melanotos - SanderlingSanderlingThe 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...
, "Calidris" alba or Crocethia alba - Western SandpiperWestern SandpiperThe Western Sandpiper, Calidris or Erolia mauri, is a small shorebird.Adults have dark legs and a short thin dark bill, thinner at the tip. The body is brown on top and white underneath. They are reddish-brown on the crown. This bird can be difficult to distinguish from other similar tiny...
, "Calidris" mauri or Ereunetes mauri - Purple SandpiperPurple SandpiperThe Purple Sandpiper, Calidris, Arquatella or Erolia maritima is a small shorebird.Adults have short yellow legs and a medium thin dark bill with a yellow base. The body is dark on top with a slight purplish gloss and mainly white underneath. The breast is smeared with grey and the rump is black...
, "Calidris" maritima - Rock SandpiperRock SandpiperThe Rock Sandpiper is a small shorebird.Adults have short yellow legs and a medium thin dark bill. The body is dark on top with a slight purplish gloss and mainly white underneath. The breast is smeared with grey and the rump is black...
, "Calidris" ptilocnemis - Temminck's StintTemminck's StintTemminck's Stint, Calidris or Erolia temminckii, is a small wader.This stint's breeding habitat is bogs and marshes in the taiga of Arctic northern Europe and Asia. It will breed in southern Scandinavia and occasionally Scotland. It has a distinctive hovering display flight. It nests in a scrape...
, "Calidris" temminckii - Buff-breasted SandpiperBuff-breasted SandpiperThe Buff-breasted Sandpiper, Tryngites subruficollis, is a small shorebird. It is a calidrid sandpipers and currently considered to be the only member of the genus Tryngites. Indeed, it probably belongs in the genus Calidris itself, or more precisely with the small species thereof which should be...
, "Tryngites" subruficollis
- Semipalmated Sandpiper
- Genus Philomachus
- Ruff, Philomachus pugnax
- Broad-billed SandpiperBroad-billed SandpiperThe Broad-billed Sandpiper is a small wading bird. It is the only member of the genus Limicola; some have proposed that it should be placed in the genus Erolia with the "stint" sandpipers, but more recent research suggests that it is should rather go into the genus Philomachus with the ruff and...
, Philomachus falcinellus / Limicola falcinellus ("Erolia falcinella") - Sharp-tailed SandpiperSharp-tailed SandpiperThe Sharp-tailed Sandpiper, Calidris acuminata is a small wader.- Taxonomy :More recently, a review of new data has indicated that this bird should perhaps better be placed into the genus Philomachus- as P...
, Philomachus acuminatus / Calidris acuminata
- Genus Micropalama (doubtfully valid; Erolius s.str.?)
- Stilt SandpiperStilt SandpiperThe Stilt Sandpiper, Calidris himantopus or Micropalama himantopus, is a small shorebird; it bears some resemblance to the smaller calidrid sandpipers or "stints". DNA sequence information is incapable of determining whether it should be placed in Calidris or in the monotypic genus Micropalama...
, Micropalama himantopus / Calidris himantopus
- Stilt Sandpiper
- Genus Eurynorhynchus (doubtfully valid)
- Spoon-billed SandpiperSpoon-billed SandpiperThe Spoon-billed Sandpiper , is a small wader which breeds in northeastern Russia and winters in Southeast Asia.- Taxonomy and systematics :...
, Eurynorhynchus pygmeus / Calidris pygmeus
- Spoon-billed Sandpiper
- incertae sedis (Erolia s.str.?)
- Curlew SandpiperCurlew SandpiperThe Curlew Sandpiper is a small wader that breeds on the tundra of Arctic Siberia. It is strongly migratory, wintering mainly in Africa, but also in south and southeast Asia and in Australasia...
, ?Calidris ferruginea
- Curlew Sandpiper
As mentioned above, there exists some material of birds essentially identical to calidriid sandpipers from before the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
. An undescribed species is known from the Early Miocene
Early Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
of Dolnice (Czechia). Tringa gracilis (Early Miocene of WC Europe) and Tringa minor (= Totanus minor, Erolia ennouchii) from the Middle Miocene of Grive-Saint-Alban (France) are scolopacids of rather uncertain affiliations; they might be charadriids.