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Calidris sp.

Calidris sp.


Family: Scolopacidae
Order: Charadriiformes
Class: Aves
Phylum / Division: Chordata
Kingdom: Animalia

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Description


Encompasses a diverse assemblage of small to medium-sized shorebirds, typically displaying body lengths ranging from 12 to 28 centimeters, wingspans between 30 and 50 centimeters, and body masses that vary considerably from 20 to upwards of 200 grams, largely dictated by premigratory hyperphagic lipid deposition. These birds possess streamlined, spindle-shaped silhouettes mounted on slender tarsometatarsi and elongated toes, often lacking a functional hallux to facilitate efficient cursorial locomotion over unstable substrates. The bill exhibits remarkable functional disparity; typically pigmented in deep blackish or horn tones, it varies from short and straight to noticeably decurved or slightly expanded at the tip, densely populated with clusters of Herbst corpuscles providing mechanoreceptive sensory capability. The plumage exhibits pronounced seasonal dichromatism; the alternate breeding attire features intricate mixtures of rufous-chestnut, fiery cinnamon, buff, and velvety black patterns concentrated on the mantle, crown, and breast, contrasting sharply with the cryptic basic non-breeding dress dominated by uniform ash-gray, pale drab-brown, and clean white ventral surfaces.

Geographical distribution: Features a cosmopolitan range propelled by extraordinary hemispheric migration flyways. Breeding territories are confined to high-latitude and circumpolar regions across the Northern Hemisphere, encompassing maritime and alpine tundras throughout Alaska, the Canadian Arctic Archipelago, coastal Greenland, northern Fennoscandia, and extensive sectors across Siberian Russia. Following post-breeding dispersal, migratory movements progress along globally celebrated paths including the Pacific Americas Flyway, the Atlantic Americas Flyway, the East Atlantic Flyway, and the East Asian-Australasian Flyway. Wintering concentrations settle along tropical, temperate, and subantarctic coastlines of South America, coastal Africa, the Indian subcontinent, insular Southeast Asia, and Australasia, with non-breeding extremities reaching coastal shelves down to Tierra del Fuego.

Habitat: Occupies barren, open arctic and subarctic tundra during the short summer, showing affinity for wet moss-sedge meadows, boggy polygonal depressions, and rocky dwarf-shrub heathlands. During passage and non-breeding residence, the species group relies on an expansive variety of coastal and inland wetlands. Optimal densities occur across broad intertidal mudflats, wave-swept sandy ocean beaches, sheltered estuaries, hypersaline lagoons, salt evaporators, and seasonal freshwater impoundments or flooded agrarian plains where soft waterlogged sediment is accessible.

Feeding: Demonstrates a predominantly zoobenthic trophic regime, combining visual hunting and tactile interstitial probing. Its prey spectrum consists mainly of marine polychaetes, minute bivalves, hydrobiid snails, amphipods, copepods, and larval instars of chironomids and aquatic beetles in continental fresh waters. Specialized members within this group are capable of harvesting intertidal biofilm through modified tongue structures and mucous traps, extracting energetic microphytobenthos directly from surficial mud. Foraging mechanics involve rapid vertical stitching actions into saturated silt, exploratory pecking along dynamic wave-wash zones, and selective snatching from water margins.

Behavior: Shows profound sociability during the non-breeding cycle, routinely aggregating into dense roosting and foraging flocks that encompass thousands of conspecific and heterospecific shorebirds. Flocks exhibit spectacular aerial coordination, performing tightly orchestrated evasive sweeps to confuse raptors such as peregrine falcons, reflecting synchronized light pulses as flock members simultaneously expose their white bellies and dark dorsal surfaces. Daily regimes are fundamentally governed by semidiurnal tidal cycles; feeding intensity peaks during receding tides, while rising waters compel retreat to communal supratidal roosts to conserve metabolic energy.

Nesting: Occurs on cold arctic soils shortly after the summer snowmelt. The nest is a simple, cryptic depression or scrape sculpted into patches of lichens, moss, or dry grassy hummocks, sparsely carpeted with fallen leaves of dwarf willow (Salix) or dry dwarf birch. The female routinely deposits a clutch of 4 pyriform eggs (rarely 3) engineered to fit tightly within the brood patch, exhibiting olive, buffy, or pale greenish backgrounds heavily marked with russet-brown and dark umber blotches. Mating systems within the genus span an evolutionary spectrum, incorporating monogamy, lekking polygyny, sequential polyandry, and varying models of uniparental care by either sex. Incubation lasts approximately 18 to 24 days. The newly hatched chicks are exceptionally nidifugous; born fully covered in camouflaging down, they leave the scrape within hours of hatching to pursue independent invertebrate foraging under the guidance of one or both parents.

Conservation status: Spans multiple categories on the IUCN Red List of Threatened Species, with several widely distributed taxa categorized as Least Concern, whereas specialized or declining species face alarming statuses including Near Threatened, Vulnerable, or Critically Endangered. Primary threats stem from catastrophic degradation of vital migratory stopovers, particularly driven by urban and industrial land reclamation around the Yellow Sea, accelerated climate alteration inducing the shrubification and desiccation of arctic tundra, marine chemical contaminants, and the disruption of coastal invertebrate communities from commercial benthic harvesting.



Compilation and publication: EcoRegistros – 24/10/2026




Geographic distribution


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Species photographs

Count: 5

Foto
Photography ID: 606709
  Immature

Nisia floresta
Rio Grande do Norte
Brazil
10/19/2024
Lucas Martín
Foto
Photography ID: 481575
  Adult

Quemú Quemú
La Pampa
Argentina
02/06/2022
Hugo Alberto Valderrey
Foto
Photography ID: 272755
 
Calchaquí
Santa Fe
Argentina
04/08/2018
Federico Nagel
Foto
Photography ID: 187089
  Adult

Tulum
Quintana Roo
Mexico
01/14/2017
Guillermo Garcia


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Species vocalizations

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Species reports



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Species records

Count: 93



Page 1 of 10
Record IDDateExact timeCountryProvince / departmentPlaceFilmedPhotographedRecorded vocalObservedHeardWounded or deadNumber of individualsUser or BibliographyDetail
252739308/09/2026ArgentinaBuenos AiresCosta de Hudson--Costanera, Berazategui3Gabriel Carbajales
245612104/04/2026ArgentinaSanta FeLaguna Melincué, Melincué25Pablo Bruni
249655819/02/2026ArgentinaBuenos AiresCostanera de Quilmes1Pablo Richter
235486807/09/2025ArgentinaBuenos AiresLaguna Espinoza, Darregueira150Mauro Desch
255110519/04/2025ArgentinaSaltaQuebrada Lizoite, Santa Victoria300Giselle Mangini
224788509/02/2025ArgentinaBuenos AiresEstancia Nahuel Ruca2Faustino Hollmann
264288721/12/2024ArgentinaSanta CruzLa Loberia, Deseado15Facundo Gandoy
255110421/12/2024ArgentinaSanta CruzLa Loberia, Deseado15Giselle Mangini
218443602/11/2024ArgentinaCorrientesInmediaciones Cambá trapo, Camino de Colonia Carlos Pellegrini a Esteros del Camba Trapo5Pablo Bruni
218372419/10/2024BrazilRio Grande do NorteCamurupim, Nisia florestaLucas Martín
Page 1 of 10

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Recommended citation
Please use the following reference when citing this species account.
EcoRegistros. 2026. Calidris sp. – Species account. Accessed from www.ecoregistros.org on 30/10/2026.