The pied avocet (Recurvirostra avosetta) is a species of wader in the Recurvirostridae family, the only member of the genus Recurvirostra found in Europe.

This characteristic wader of coastal lagoons and marshes is easily recognizable by its long, upturned bill, long legs, and striking black-and-white plumage. Measuring approximately in length with a wingspan of about , it is a relatively large species that feeds on various invertebrates in water and mudflats, captured using its distinctive bill. It typically nests in colonies of 10 to 70 pairs on islets or dikes near water, laying usually four eggs in a simple, shallow scrape in the sand. Highly territorial when defending its chicks against conspecifics or predators—such as various raptors, corvids, and mammals—the pied avocet has a lifespan of about 20 years, with a record of 27 years.

The species has a wide distribution, spanning western Europe, central Asia, the Indian subcontinent, and Africa. Part of its population is migratory, undertaking long journeys south to its wintering grounds, while others are resident. In France, it is found along the English Channel, Atlantic coast, and Mediterranean, with northern populations joining in winter, while some individuals winter in Southern Europe or Africa.

Described by Carl Linnaeus in 1758, the pied avocet is one of four species in its genus, the others inhabiting different continents. Classified as Least Concern (LC) by the IUCN due to its extensive range and relatively large population, it nonetheless faces threats from anthropogenic factors such as habitat destruction, climate change, and pollution. Numerous scientific programs aim to better understand its biology, particularly its migratory routes, to enhance its protection.

Description

Adults have a striking black-and-white plumage, with a black cap extending to the back of the neck. The primaries are black, with the base of the inner primaries white, while the secondary coverts are dark grey. The rectrices are pale grey-brown in the middle and white elsewhere. The species shows no seasonal plumage variation. The tail is white, and the legs are bluish. The long, black beak is slender and upturned. The male's bill is longer and less curved, while the female's is shorter and more distinctly curved. The black markings on the female's head may occasionally appear browner and less distinct. with a wingspan of , occasionally up to . The wing of an adult male measures , while that of a female measures .

The bill measures in males and is slightly shorter in females, ranging from . The legs extend beyond , with a tarsus of in males and in females.

Its breeding habitat is shallow lakes with brackish water and exposed bare mud. It nests on open ground, often in small groups, sometimes with other waders. Three to five eggs are laid in a lined scrape or on a mound of vegetation.

Vocalizations

The contact and alarm calls, often emitted by adults when chicks are threatened, are a fluty whistle, sometimes plaintive, resembling plut-plut-plutt or klup-klup-klup. Paul Géroudet notes kvit-kvit-kvit when birds are excited, as well as krit-krit or kvèt. Near predators, avocets may emit kriyu. They also produce soft buk-buk during chick-rearing or glouglou... grrugrrugrru with mates during breeding.

Diet and feeding techniques

alt=Photo of a bird swimming in water and eating a small invertebrate with its bill.|left|thumb|Feeding on small invertebrates with its curved bill.

The pied avocet primarily feeds on small benthic invertebrates, such as annelids, small crustaceans like Corophium, oligochaete and polychaete worms (e.g., Hediste diversicolor or Polydora species), and bivalve molluscs.

It occasionally eats small fish, seeds, and small roots.

It uses its bill to probe the sediment surface, making lateral pecks to find prey, or catches them by sight. It may also peck on beaches or swim in deeper water, dipping its head like a duck. Survival and return rates in the Atlantic range from 48–75% (average 58%) for first-year birds and 78–100% (average 90%) for adults, depending on the year.

Reproduction

Nest and eggs

alt=Photo of a beige egg speckled with black.|right|thumb|Egg from the [[Muséum de Toulouse|Toulouse Museum collection.]]

The species is semi-colonial. It nests in dense colonies of 10–70 pairs, It is monogamous, with pairs forming soon after arriving at breeding sites.

The nest is a shallow scrape, averaging in diameter, ranging from , Islets improve hatching success by reducing predation. Unlike the Eurasian oystercatcher, the avocet does not adjust nest size for water level changes.

Nests often include shell fragments, particularly Cerastoderma glaucum, and vegetation like samphire, grasses, goosefoots, sea-lavender, bromes, widgeon grass, or saltmarsh bulrush.

In colonies, nests are typically spaced to , though in an Iranian colony, the average was . Clutches range from 69 to 92 days, Eggs measure and weigh about . Incubation lasts 19–34 days, averaging 23 days. Both parents incubate, with a ritual involving debris-tossing and sliding under the incubating bird to take over. This ritual diminishes over time. The non-incubating parent may feed up to from the colony. In the first hours, they alternate between sheltering under parents and exploring nearby. Within 72 hours, the family moves to nearby feeding areas.

Both parents protect chicks from predators and weather. Adults use distraction displays, such as feigning a broken wing or swooping at intruders.

Reproductive success varies by year and site, with productivity of 0.49–0.52 fledglings per pair on the Atlantic and Channel coasts, 0.45–0.63 in Languedoc colonies, and 0.04–0.22 in Camargue.

Sexual maturity varies: 25% of French birds breed in their first year, 40% in their second, while North Sea birds mature between two and five years. Generally, maturity is reached at 2–3 years.

Nests may be destroyed by flooding Poor water quality or inappropriate salinity can limit food availability,

Chick dispersal for food increases mortality risk, and harsh weather affects chicks aged two to three weeks. and Eurycestus avoceti, first observed in the American avocet and later in Camargue individuals, with the crustacean Artemia salina as an intermediate host.

Habitats

alt=Color photo taken by a pond, with houses in the background and a dirt path on the side.|right|thumb|Typical Mediterranean habitat, here at the Frontignan Salt Flats in Hérault.

The species frequents coastal habitats. In winter, it gathers in groups on soft substrates like brackish or saline bays, sandbanks, estuaries, lagoons, deltas, or intertidal mudflats, used for resting and feeding. or dikes with samphire. Preferred islets are elongated, long and wide, offering a clear view of nearby water. It has been observed breeding near hunting blinds. It breeds up to in altitude in Anatolia.

Distribution

The pied avocet is a Turano-Mediterranean species, found in the Palearctic. Its fragmented range spans European coastlines from southern Scandinavia and the Baltic states (e.g., Estonia since 1964) to the Iberian Peninsula, the Mediterranean, Black Sea, and eastern European plains (Ukraine, Bulgaria, Romania, Hungary). Major European populations are in the Netherlands, Germany, Denmark, Spain (southern and Ebro Delta), Italy (Po Delta and Sardinia), France, and Russia. It occurs on southern England coasts (about 150 pairs in 1979), having returned to breed in 1947 in Suffolk’s Minsmere RSPB reserve after disappearing in the mid-19th century.

In Asia, it ranges from Turkey (Anatolia) to northern Mongolia, northern China, southern Russian Far East, Kazakhstan, and Middle Eastern countries (Iran, Iraq, Jordan). Western European birds winter in West Africa (Senegal, Gambia, Niger) and Mediterranean countries, especially Spain and Portugal (one-third of migratory European birds). Later, a single specimen was found in 14th-century deposits in Abbeville, Somme.

It was noted as breeding in Camargue and Languedoc only from the early 20th century. It established breeding on the Atlantic coast from the 1950s, starting in Vendée in 1952, reaching Morbihan by 1983, and the English Channel and Somme Bay in the 1970s. It likely bred in France before the 20th century, possibly colonizing or recolonizing spontaneously from its Mediterranean range. It is less common along the English Channel, mainly in Somme Bay and Lower Normandy, and in the Mediterranean, primarily in Camargue and Montpellier ponds.

In Belgium

The species is distributed in the Zwin Nature Park, Antwerp, and Ghent, with over 480 breeding pairs. Its successful recolonisation at Minsmere, Suffolk, in 1947 led to its adoption as the logo of the Royal Society for the Protection of Birds. The pied avocet has spread inland and northwards and westwards in Britain since then and it has bred in Wales and in Scotland in 2018 at Skinflats.

Nomenclature and taxonomy

Etymology

The term "avocet" derives from the old Italian avosetta, attested in the 17th century, of unknown origin. In French, "avocette" stems from a 1760 error by Brisson, who replaced the "s" with a "c" in his bilingual Latin-French Ornithologie. This spelling was adopted by Buffon and standardized across languages. This species gets its English and scientific names from the Venetian word avosetta. It appeared first in Ulisse Aldrovandi's Ornithologia (1603). While the name may refer to black and white outfits once worn by European advocates or lawyers, the actual etymology is uncertain. Other common names include black-capped avocet, Eurasian avocet or just avocet.

It is one of four species of avocet that make up the genus Recurvirostra. The genus name is from Latin recurvus, "curved backwards" and rostrum, "bill". A 2004 study combining genetics and morphology showed that it was the most divergent species in the genus.

Phylogeny

The mitochondrial genome is base pairs long.

Fossil record

The species is recorded from the Middle and Late Pleistocene in the Mediterranean region, specifically in Sicily. It is also reported in northeastern Bulgaria, along the Black Sea coast, at the Yaylata site, in a deposit dating to the mid-Holocene, alongside other bird species.

Threats and conservation

The global population was estimated to be between 280,000 and 470,000 individuals in 2015. The overall population trend is unknown. In Europe, the species' population is estimated at between 117,000 and 149,000 adult individuals in 2015, equivalent to 58,400 to 74,300 breeding pairs, or, according to another source, between 38,000 and 57,000 pairs.

The Western European breeding population is estimated at 73,000 birds, wintering across Europe and Africa, from the Netherlands to northern Guinea, with 22,500 individuals in Sub-Saharan Africa. In contrast, along the Atlantic coast, numbers increased by 107% since 1980. The Mediterranean wintering population has also risen by 200% since 1980, though this is tempered by strong interannual variations. Between 1996 and 2011, the Mediterranean breeding population increased by over 50%, reaching approximately 1,500 pairs.

The species is considered vulnerable (VU) as a breeding species on the regional red list of Provence-Alpes-Côte d'Azur, near threatened (NT) on the red list of breeding birds in Languedoc-Roussillon, vulnerable (VU) in Poitou-Charentes, and least concern (LC) in Pays de la Loire. In Brittany, it is vulnerable (VU) as a breeding species and near threatened (NT) as a migrant. In Normandy, it is critically endangered (CR) as a breeding species and endangered (EN) as a wintering species. In Nord-Pas-de-Calais, it is vulnerable (VU) as a breeding species. In Belgium, specifically Wallonia, it is considered vulnerable (VU).

Threats

alt=Map showing the impact of the Erika oil spill on the French Atlantic coast.|thumb|Pollution (oil spill) from the Erika on French coasts during the winter of 1999–2000.

Various threats, mostly of anthropogenic origin, affect the Pied Avocet. The European population is relatively small and confined to a limited number of sites, particularly in winter. Many key wintering sites are located near oil port facilities, posing a significant petrochemical risk, as evidenced by a collision between two butane carrier ships in January 2006 in the Loire Estuary. The species may also be affected by reduced river flows in certain areas, such as in China.

Pollution is harmful to the Pied Avocet, with pollutants such as PCBs, insecticides, lead, mercury, and selenium found in eggs and bird tissues in Europe.

Finally, the species may occasionally be affected by egg collection for private collections.

Conservation measures

alt=Image showing bird leg rings, one blue with a white code C51 and two metal rings with unique codes placed on cardboard.|left|thumb|Metal and Darvic rings used for banding an avocet chick at Salins-d'Hyères (Var).

The species is protected in France under the Nature Protection Law of July 10, 1976, and its implementing decrees. The European Commission’s 1979 Birds Directive and the 1979 Bern Convention on European wildlife ensure full legal protection, prohibiting disturbance of birds and their nests. Increased breeding pairs have also been noted with the introduction of livestock grazing in coastal meadows near breeding sites, reducing vegetation cover and improving visibility and predator detection.

Numerous color-banding programs, using metal and colored rings, exist in Europe, enhancing ornithologists’ understanding of the species’ ecology and migratory movements, as well as improving monitoring of breeding behavior and site management.

<gallery>

File:Saebelschnaebler (Recurvirostra avosetta).jpg|Adult feeding

File:Recurvirostra avosetta-pjt2.jpg|Adult in flight

File:Avocet from the Crossley ID Guide Britain and Ireland.jpg|ID composite

File:Pied Avocet.ogv|Video showing bird seeking food

File:Pied Avocet in LRK.jpg|Pied avocets in Little Runn of Kutch, India

File:Skärfläckans fötter med simhud.jpg|Unlike other waders, the pied avocet has webbed feet, and can swim well.

</gallery>

References

  • (Pied) avocet species text in The Atlas of Southern African Birds