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For other uses, see Curlew (disambiguation).
For other uses of "Numenius", see Numenius.

Curlew
Long-billed curlew (Numenius americanus)
Fishing Pier, Goose Island State Park, Texas
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Scolopacidae
Genus: Numenius
Brisson, 1760
Type species
Scolopax arquata
Linnaeus, 1758
Species

N. phaeopus
N. hudsonicus
†N. tenuirostris
N. arquata
N. americanus
N. madagascariensis
N. minutus
†(?)N. borealis
N. tahitiensis

Synonyms

Palnumenius Miller, 1942

The curlews (/ˈkɜːrljuː/) are a group of nine species of birds in the genus Numenius, characterised by their long, slender, downcurved bills and mottled brown plumage. The English name is imitative of the Eurasian curlew's call, but may have been influenced by the Old French corliu, "messenger", from courir, "to run". It was first recorded in 1377 in Langland's Piers Plowman "Fissch to lyue in þe flode..Þe corlue by kynde of þe eyre".[1] In Europe, "curlew" usually refers to one species, the Eurasian curlew (Numenius arquata).

Taxonomy

[edit]

The genus Numenius was erected by the French scientist Mathurin Jacques Brisson in his Ornithologie published in 1760.[2] The type species is the Eurasian curlew (Numenius arquata).[3] The Swedish naturalist Carl Linnaeus had introduced the genus Numenius in the 6th edition of his Systema Naturae published in 1748,[4] but Linnaeus dropped the genus in the important tenth edition of 1758 and put the curlews together with the woodcocks in the genus Scolopax.[5][6] As the publication date of Linnaeus's sixth edition was before the 1758 starting point of the International Commission on Zoological Nomenclature, Brisson and not Linnaeus is considered as the authority for the genus.[7] The name Numenius is from Ancient Greek noumenios, a bird mentioned by Hesychius. It is associated with the curlews because it appears to be derived from neos, "new" and mene, "moon", referring to the crescent-shaped bill.[8] The genus now contains nine species:[9]

The following cladogram showing the genetic relationships between the species is based on a molecular phylogenetic study published in 2023.[10]

Numenius

Little curlew (N. minutus)

Bristle-thighed curlew (N. tahitiensis)

Eurasian whimbrel (N. phaeopus)

Hudsonian whimbrel (N. hudsonicus)

Long-billed curlew (N. americanus)

Eskimo curlew (N. borealis)

Far Eastern curlew (N. madagascariensis)

Eurasian curlew (N. arquata)

Slender-billed curlew (N. tenuirostris)

Description

[edit]

They are one of the most ancient lineages of scolopacid waders, together with the godwits which look similar but have straight bills.[11] Curlews feed on mud or very soft ground,[12][13] searching for worms and other invertebrates with their long bills. They will also take crabs and similar items.

Distribution

[edit]
The Eurasian curlew pictured in the coat of arms of Oulunsalo, a former municipality of North Ostrobothnia, Finland

Curlews enjoy a worldwide distribution. Most species exhibit strong migratory habits and consequently one or more species can be encountered at different times of the year in Europe, Ireland, Britain, Iberia, Iceland, Africa, Southeast Asia, Siberia, North America, South America and Australasia.

The distribution of curlews has altered considerably in the past hundred years as a result of changing agricultural practices. For instance, Eurasian curlew populations have suffered due to draining of marshes for farmland, whereas long-billed curlews have shown an increase in breeding densities around areas grazed by livestock.[14][15] As of 2019, there were only a small number of Eurasian curlews still breeding in Ireland, raising concerns that the bird will become extinct in that country.[16]

The stone-curlews are not true curlews (family Scolopacidae) but members of the family Burhinidae, which is in the same order Charadriiformes, but only distantly related within that.

Genus Numenius – Brisson, 1760 – nine species
Common name Scientific name and subspecies Range Size and ecology IUCN status and estimated population
Eurasian whimbrel

Numenius phaeopus
(Linnaeus, 1758)

Five subspecies
  • N. p. islandicus Brehm, C.L., 1831
  • N. p. phaeopus (Linnaeus, 1758l)
  • N. p. alboaxillaris Lowe, 1921
  • N. p. rogachevae Tomkovich, 2008
  • N. p. variegatus (Scopoli, 1786)
subarctic Asia and Europe as far south as Scotland
Map of range 		Size:

Habitat:

Diet: 		 LC 


Hudsonian whimbrel

Numenius hudsonicus
Latham, 1790

Two subspecies
  • Numenius hudsonicus rufiventris – Vigors, 1829
  • Numenius hudsonicus hudsonicus – Latham, 1790
southern North America and South America. It
Map of range 		Size:

Habitat:

Diet: 		 LC 


Slender-billed curlew † (Last seen in 1995[17])


Numenius tenuirostris
Vieillot, 1817 		Russia, Persian gulf, in Kuwait and Iraq.
Map of range 		Size:

Habitat:

Diet: 		 EX 


Eurasian curlew

Numenius arquata
(Linnaeus, 1758)

Three subspecies
 temperate Europe and Asia
Map of range 		Size:

Habitat:

Diet: 		 NT 


Long-billed curlew

Numenius americanus
Bechstein, 1812 		central and western North America
Map of range 		Size:

Habitat:

Diet: 		 LC 


Far Eastern curlew

Numenius madagascariensis
(Linnaeus, 1766) 		northeastern Asia, including Siberia to Kamchatka, and Mongolia. coastal Australia, with a few heading to South Korea, Thailand, Philippines and New Zealand Size:

Habitat:

Diet: 		 EN 


Little curlew

Numenius minutus
Gould, 1841 		Australasia, far north of Siberia. Size:

Habitat:

Diet: 		 LC 


Bristle-thighed curlew

Numenius tahitiensis
(Gmelin, JF, 1789) 		tropical Oceania, and includes Micronesia, Fiji, Tuvalu, Tonga, Hawaiian Islands, Samoa, French Polynesia and Tongareva, lower Yukon River and Seward Peninsula
Map of range 		Size:

Habitat:

Diet: 		 NT 


Eskimo curlew – †? (Last seen in 1987[18])


Numenius borealis
(Forster, 1772) 		western Arctic Canada and Alaska, Pampas of Argentina
Map of range 		Size:

Habitat:

Diet: 		 CR 


The Late Eocene (Montmartre Formation, some 35 mya) fossil Limosa gypsorum of France was originally placed in Numenius and may in fact belong there.[19] Apart from that, a Late Pleistocene curlew from San Josecito Cave, Mexico has been described.[20] This fossil was initially placed in a distinct genus, Palnumenius, but was actually a chronospecies or paleosubspecies related to the long-billed curlew.

The upland sandpiper (Bartramia longicauda) is an odd bird which is the closest relative of the curlews.[11] It is distinguished from them by its yellow legs, long tail, and shorter, less curved bill.

References

[edit]

Further reading

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Curlew

View on Grokipedia
from Grokipedia
Curlews are a (Numenius) of eight of medium- to large-sized shorebirds in the Scolopacidae, characterized by long, slender, downcurved bills adapted for probing mud and soil in search of prey, along with mottled brown providing in their habitats. These waders breed predominantly in northern temperate and regions, favoring open grasslands, moors, and , before undertaking extensive migrations to winter in coastal estuaries, wetlands, and mudflats of tropical and subtropical latitudes. Notable for their distinctive, haunting calls that inspired their name—evoking the sound "cur-lee"—curlews exhibit high adult survival rates but low in fragmented s, rendering populations vulnerable to declines. Several species face severe conservation threats: the (N. borealis) is presumed extinct following massive 19th-century overhunting, while the (N. tenuirostris) remains critically endangered with no confirmed breeding sites, attributed to loss from agricultural expansion and wetland drainage rather than climate effects alone. The (N. americanus), the largest North American shorebird, persists but shows regional declines due to conversion, underscoring the need for targeted protection across flyways.

Taxonomy and Phylogeny

Genus Classification

The genus Numenius belongs to the family Scolopacidae within the order Charadriiformes and encompasses species of wading birds known as curlews. These birds are distinguished by their long, slender, decurved bills, mottled brown plumage, and adaptations for shorebird lifestyles, including long legs for wading. The genus was established by French ornithologist Mathurin Jacques Brisson in 1760, with the type species being the Eurasian curlew (Numenius arquata), originally classified by Carl Linnaeus as Scolopax arquata in 1758. The name Numenius originates from the Ancient Greek noumēnios, denoting a bird—likely the curlew—whose bill evokes the of a new . Phylogenetic analyses confirm Numenius as a monophyletic group within Scolopacidae, forming sister taxa among curlew species and positioned distantly from other genera in the family, reflecting deep evolutionary divergence. This placement underscores the genus's basal role in the Scolopaci , supported by evidence.

Species Diversity and Relationships

The genus Numenius encompasses eight species of curlews, all shorebirds in the Scolopacidae distinguished by their long, decurved bills adapted for probing . These species vary in size, ranging from the diminutive Little Curlew (N. minutus) at approximately 30 cm in length to the larger (N. arquata) exceeding 50 cm, with distributions spanning , , and the Pacific. Two species—the (N. borealis), extinct since the early 20th century, and the (N. tenuirostris), presumed extinct or critically endangered with no confirmed sightings since 2009—highlight significant losses in diversity, attributed to hunting, habitat alteration, and climate factors.
Scientific NameCommon NameConservation Status (IUCN, 2023)
N. minutusLittle CurlewLeast Concern
N. borealisExtinct
N. phaeopusWhimbrelLeast Concern
N. tenuirostrisCritically Endangered (possibly extinct)
N. arquataNear Threatened
N. madagascariensisVulnerable
N. americanusLeast Concern
N. tahitiensisVulnerable
Phylogenetic analyses based on morphological and molecular data confirm the monophyly of Numenius, placing it within the tribe Numeniini of subfamily Scolopacinae, with Bartramia (upland sandpipers) as a potential sister taxon. Mitochondrial DNA studies, including cytochrome B and complete mitogenomes, reveal interspecies relationships where the Slender-billed Curlew clusters closely with the Eurasian, Far Eastern, and Long-billed curlews, diverging by less than 3% in cytochrome oxidase I sequences from the Eurasian Curlew. The Bristle-thighed Curlew appears basal among sampled species, while the Whimbrel and Little Curlew form a distinct smaller-bodied clade; comprehensive phylogenomic reconstructions indicate that Holocene megafaunal extinctions, rather than climate alone, contributed to a 40.6% loss in the clade's evolutionary distinctiveness through reduced genetic diversity in surviving lineages. These findings underscore the genus's evolutionary cohesion but highlight gaps in whole-genome data for extinct taxa like the Eskimo Curlew, limiting full resolution of divergence times estimated at 2-5 million years ago for major splits.

Fossil Record

The genus Numenius first appears in the fossil record during the Middle Miocene, approximately 15–20 million years ago, based on fragmentary remains referred to the genus without assignment to specific species. A notable specimen, a complete left from San Josecito Cave in , (dated to the Rancholabrean land-mammal age, roughly 250,000–11,700 years ago), was originally described as the holotype of Palnumenius victima but subsequent analysis determined it inseparable from Numenius at the generic level, rendering Palnumenius a junior subjective . This fossil measures 72 mm in length, falling within the lower range of modern male N. americanus (69.8–81.5 mm), with minor morphological differences such as a more abrupt internal cotyla projection and a deeper extensor groove, tentatively interpreted as a temporal or geographic variant of the (N. americanus). The overall fossil record of Numenius remains sparse, with no well-defined extinct species distinct from extant ones beyond subfossil remains (e.g., abundant N. tahitiensis bones from pre-human deposits on Moloka'i and Kaua'i, , indicating formerly broader distributions). Recent extinctions, such as N. borealis and N. tenuirostris, are documented through historical specimens rather than paleontological fossils.

Physical Characteristics

Morphology and Adaptations

Curlews in the Numenius are large waders characterized by their elongated bodies, long necks, and notably decurved bills that often exceed half the length of the head and neck combined, with bill lengths ranging from 70 mm in smaller like the little curlew (N. minutus) to over 150 mm in the (N. americanus). Their legs are proportionally long, typically dull gray or greenish, facilitating wading through shallow water and mudflats without excessive energy expenditure. Plumage is predominantly cryptic, featuring mottled browns, buffs, and streaks on the upperparts and underparts, providing against grassland and estuarine substrates during breeding and non-breeding seasons. The decurved bill represents a primary morphological adaptation for subsurface foraging, allowing curlews to probe deeply into soft sediments—up to depths beyond 15 cm—to extract burrowing prey such as annelid worms, crustaceans, and bivalves that are inaccessible to straighter-billed shorebirds. The bill's curvature specifically aids in maneuvering around buried prey's U-shaped burrows and withdrawing long, intact annelids without fragmentation, enhancing feeding efficiency in intertidal and prairie habitats. Across the genus, bill length correlates with substrate type and prey depth, with longer bills in species favoring deep-probing in mud over surface pecking in drier grasslands. Sexual dimorphism in size and bill morphology is prevalent, with females generally larger and possessing longer, more robust bills than males, a reversed common in scolopacids that may reduce for food resources or signal fitness during mate selection. This dimorphism enables niche partitioning, as females target deeper or larger prey, while the overall streamlined body form, including pointed wings spanning up to 90 cm, supports endurance for long-distance migrations spanning continents. The mottled extends to downy chicks, which are precocial and rely on visual for predator avoidance in open nesting grounds.

Plumage, Size Variation, and Sexual Dimorphism

Curlews in the Numenius display cryptic adapted for concealment in open habitats, characterized by mottled brownish upperparts with dark streaks and barring on a buff or background, and paler, often or streaked underparts. This pattern persists year-round without marked seasonal variation in most , though juveniles feature fresher, buff-tipped feathers for added . lacks sexual dichromatism, with males and females indistinguishable by color or pattern. Size varies substantially across the genus, reflecting ecological adaptations; for instance, the (N. madagascariensis) measures 53–66 cm in and weighs 565–1,150 g, while the (N. arquata) ranges 48–57 cm and 415–980 g. Within species, body mass and dimensions fluctuate with age, condition, and geography; adult Long-billed curlews (N. americanus) span 50–65 cm and 490–950 g. Bill length, a defining trait, scales with body size and can exceed 20 cm in larger species, enabling deep probing for prey. Sexual dimorphism manifests chiefly in size, with females larger than males in body length, mass, and especially bill length—a pattern consistent across to facilitate division of niches during breeding. In the , female bills average 13–15.2 cm versus 10–12.4 cm in males; similarly, females average 170 mm bills compared to 139 mm in males. This size disparity aids sex determination via but does not extend to plumage differences.
SpeciesLength (cm)Wingspan (cm)Weight (g)Female Bill Length (cm) Advantage
Eurasian (N. arquata)48–5789–106415–980~2–3 cm longer than males
Long-billed (N. americanus)50–6562–89490–950~3 cm longer than males
Far Eastern (N. madagascariensis)53–66~110565–1,150Larger overall, specifics vary

Distribution and Habitat

Breeding and Non-Breeding Ranges


Species of the genus Numenius breed predominantly in the temperate and Arctic zones of the Northern Hemisphere, with non-breeding ranges extending to subtropical and tropical regions across multiple continents. All eight recognized species follow this pattern of high-latitude nesting followed by southward migration. The (N. arquata) breeds across a broad expanse from the through northwestern Europe, , and into , extending eastward to and northern . Its non-breeding range encompasses coastal and areas in , sub-Saharan , southern Asia, and parts of the , with significant winter concentrations in the hosting approximately 30% of the western European population. The whimbrel (N. phaeopus), one of the most widespread curlews, breeds in and from across northern Canada, , and to . Non-breeding grounds span from southern and the southward to in the , and from to and southern Africa in the , with migrations often involving transoceanic flights. In , the long-billed curlew (N. americanus) nests in short- to mixed-grass prairies of the , ranging from northward to the western Dakotas and southern in . It migrates to coastal estuaries, mudflats, and inland wetlands in , the , and for the non-breeding period. The (N. madagascariensis) breeds in mossy bogs and wet meadows of northeastern Asia, including , , and . Its non-breeding range is concentrated in intertidal mudflats and coastal wetlands of and , where it undertakes one of the longest migrations among shorebirds. Other species, such as the little curlew (N. minutus) in Russian forests and the (N. tahitiensis) in western , similarly shift to Pacific island chains and Australasian wetlands during non-breeding seasons.

Habitat Requirements and Preferences

Curlews in the Numenius exhibit distinct habitat preferences tied to their breeding and non-breeding phases, favoring open, low-disturbance landscapes that support nesting, , and predator avoidance. During breeding, they select sites with heterogeneous structure, including a mix of short and taller swards for cover and vigilance, such as upland moors, bogs, swampy heathlands, , damp grasslands, and meadows in temperate to boreal zones of , , and North America. These areas typically feature moderately wet or flooded conditions to facilitate access to invertebrate prey, with curlews avoiding short-cropped or arable fields in favor of taller, unmanaged grasslands. cover exerts a negative influence up to 2 km from nests, reducing occupancy, while proximity to open semi-natural habitats mitigates such effects. success is higher in bog-dominated territories compared to grasslands, though the latter support larger home ranges averaging several hundred hectares. In non-breeding seasons, curlews shift to coastal and environments, prioritizing intertidal mudflats, estuaries, saltmarshes, and brackish lagoons for their abundance of buried accessible via probe-foraging with long bills. These sites provide soft substrates and tidal cycles that expose prey, with winter distributions consistently favoring coastal over inland areas, though usage broadens to varied land covers like arable fields in colder months. Species-specific variations exist; for instance, the (N. americanus) requires 14–49 hectares of diverse topographic and vegetative breeding habitat in grasslands or prairies, emphasizing the genus-wide need for expansive, unfragmented open ground to minimize predation risk. Habitat suitability hinges on hydrological stability and low anthropogenic modification, with curlews preferring mosaics of dry and wet grasslands for chick-rearing due to higher prey in drier patches. Across populations, avoidance of built structures, drainage canals, and isolated trees underscores a requirement for unobstructed sightlines and minimal in selected territories.

Behavior and Ecology

Foraging Strategies and Diet

Curlews in the Numenius employ a primary strategy of deep probing into soft substrates such as mudflats, wet grasslands, and intertidal zones, utilizing their long, decurved bills to extract buried prey. This method relies on the bill's sensitivity to detect prey vibrations and movements subsurface, enabling access to at depths up to 10-15 cm in like the (N. americanus). Bill morphology varies by and , with longer-billed females often achieving higher foraging success rates than males in wintering habitats, as observed in Eurasian curlews (N. arquata) where female intake rates exceeded males by 20-30% due to deeper probing capabilities. Their diet is predominantly carnivorous, consisting of invertebrates such as worms, crustaceans (e.g., crabs and amphipods), (e.g., beetles and grasshoppers), and mollusks, supplemented occasionally by small vertebrates like lizards or . Prey selection is influenced more by availability than energy content, as demonstrated in eastern curlews (N. madagascariensis), which specialize on abundant soldier crabs despite lower caloric yields from alternative prey. In breeding grounds, diets shift toward terrestrial and earthworms in upland grasslands, while non-breeding ranges emphasize benthic marine invertebrates in coastal estuaries. Interspecific dietary differences reflect habitat and bill adaptations; for instance, far eastern curlews (N. madagascariensis) show greater specialization on with less flexibility compared to Eurasian curlews, which exploit a broader range of prey in varied wintering sites. Long-billed curlews in winter extensively in open pastures and lots for crustaceans and , facing risks from pesticide-reduced prey populations. often occurs solitarily or in small flocks outside breeding, with birds exhibiting site fidelity to high-prey areas on wintering grounds.

Reproductive Biology and Breeding Success

Eurasian curlews form socially monogamous pairs that defend territories, with males primarily responsible for territorial displays including undulating flights. Pairs typically form upon arrival at breeding grounds in spring, constructing a simple ground scrape nest lined with vegetation in moist grasslands, moors, or bogs. Breeding occurs once per season, with clutches laid from early April to early May in northern Europe. Clutches consist of four olive-buff eggs, incubated by both sexes for 27–29 days. Incubation is shared, though females may initiate and males take over night shifts; both parents exhibit distraction displays to deter predators. Chicks are precocial, hatching covered in down and leaving the nest within hours to follow parents, who lead them to areas while providing protection and limited brooding. Fledging occurs at 32–38 days post-hatching, after which young become increasingly independent, though parents may continue guarding until migration. Breeding success is generally low, with productivity often below 0.3 fledglings per pair annually, insufficient to offset adult mortality rates of 82–95% and maintain stable populations. Nest predation by foxes, , and mustelids accounts for most failures, with daily survival rates around 0.935 during incubation yielding hatching success of 20–40% in unmanaged habitats. Targeted conservation, such as predator control, can elevate fledging to 0.6 or higher per pair.

Migration Patterns and Social Behavior

Curlews of the genus Numenius exhibit diverse migration strategies, ranging from short- to long-distance movements, typically breeding in northern temperate or regions and wintering in more southern latitudes. Most undertake post-breeding southward migrations in late summer to early fall, followed by northward spring migrations, often in flocks to reduce predation risk and optimize energy use. Migration routes vary by and , with some employing migration where northern breeding populations winter farther south than southern ones. The (N. arquata) follows the , breeding from and eastward to the and Arctic , then migrating along a northeast-southwest axis to winter along Atlantic coasts from to the , including and western . Individuals depart wintering sites in mid- to late , primarily in the evening, and return from breeding grounds starting in early June, with arrivals concentrated in late June to mid-July; northern breeders tend to winter farther south, exemplifying chain migration. The (N. americanus), North America's largest shorebird, is a short- to medium-distance migrant, shifting from interior breeding grounds in the and to coastal and inland wintering areas in , , , and ; for instance, birds from southwestern primarily head to central and , while those from eastern follow different paths, with some tracked flights passing through to . Bristle-thighed curlews (N. tahitiensis) employ oceanic routes along the Central , flying directly between breeding grounds and tropical Pacific island wintering sites. Socially, curlews are generally solitary or form loose pairs during breeding, defending territories aggressively against intruders of both sexes, with monogamous pair bonds facilitating shared incubation and chick-rearing duties that vary by and conditions. Outside the breeding season, they aggregate into flocks for migration and roosting, enhancing vigilance and efficiency, though non-breeding long-billed curlews often forage solitarily while forming mixed-sex flocks during flights and at winter roosts. curlews (N. borealis), now critically endangered, were highly social during migration, contrasting with minimal interactions on breeding grounds. Fidelity to wintering sites and areas persists across years, supporting stable social structures in non-breeding habitats.

Conservation and Population Dynamics

Populations of curlew species in the genus Numenius exhibit widespread declines, driven primarily by habitat degradation and low reproductive success, though trends vary by species and region. The Eurasian curlew (N. arquata), the most abundant and widespread, holds a global population of approximately 835,000–1,310,000 individuals and is classified as Near Threatened by IUCN criteria, reflecting ongoing reductions particularly in breeding ranges. In Europe, where 212,000–292,000 breeding pairs occur, the population has decreased by 30–49% over recent decades, with national surveys in the UK and Ireland documenting persistent annual losses of 5–10% in core areas as of 2023. Other species face more acute risks; the Far Eastern curlew (N. madagascariensis) is experiencing continued decreases, with estimates indicating past declines of 50–79% and projected future reductions of 20–40%, contributing to its Vulnerable status. The Long-billed curlew (N. americanus) in shows relative stability overall, though Great Plains subpopulations are declining while those west of the remain steady or slightly increasing as of recent demographic analyses. Critically, the slender-billed curlew (N. tenuirostris) was officially declared extinct by the IUCN in 2025, marking the first recorded global of a curlew species amid decades without confirmed sightings. The Eskimo curlew (N. borealis), historically abundant, is now considered extremely rare or possibly extinct, with no verified breeding records since the early 20th century and only sporadic vagrant sightings. Across the genus, Europe-wide demographic modeling as of 2023 indicates median population growth rates below replacement (around 0.95), underscoring the need for targeted interventions to reverse trends observed through 2024 breeding seasons.

Anthropogenic and Natural Threats

Anthropogenic threats to curlew populations primarily stem from loss and degradation, driven by agricultural intensification, drainage, and land-use changes such as and . In , conversion of s and moors to has reduced suitable breeding habitats, with drainage and reseeding eliminating areas essential for chicks; for instance, the (Numenius arquata) has experienced rapid declines in the UK, where agricultural policy shifts contributed to a loss of nested habitats. Globally, similar pressures affect migratory stopover and wintering sites, including extraction in bogs and coastal destruction, exacerbating fragmentation for species like the (N. americanus), whose nesting areas have been converted to croplands. remains a localized threat, particularly in parts of and , where legal and illegal shooting targets curlews during migration and wintering; the extinction of the (N. tenuirostris) in 2024 was partly attributed to historical overhunting combined with loss. compounds these issues through sea-level rise inundating coastal grounds and altered weather patterns disrupting migration timing, with projections indicating further squeeze in wintering regions outside protected areas. and human disturbance, such as from near breeding sites, add to nest abandonment and reduced efficiency. Natural threats include predation on eggs, chicks, and adults, which limits breeding success across curlew species. In temperate breeding grounds, generalist predators like foxes (Vulpes vulpes) and corvids (e.g., ) depredate nests at high rates, with studies in the UK showing predation accounting for up to 50-70% of egg losses in some populations; this pressure has intensified due to natural predator in fragmented landscapes. Avian predators and small mammals also target flightless molting adults on wintering grounds, as seen in declines of Arctic-breeding species. Severe weather events, including storms during long-distance migrations, pose risks of mass mortality, though quantitative data remains limited; for example, hurricane impacts on stopover sites have been linked to sporadic die-offs in North American curlews. outbreaks and for resources occur but are less documented as primary drivers compared to predation.

Conservation Efforts and Outcomes

Efforts to conserve curlews, particularly species in the genus Numenius such as the Eurasian Curlew (N. arquata) and Long-billed Curlew (N. americanus), emphasize habitat restoration, predator management, and population supplementation techniques. In the United Kingdom, the 2025 Curlew Action Plan coordinates interventions including grassland management and reduced agricultural disturbance to support breeding on moorlands and wetlands, addressing a 48% population decline since the mid-1990s. Ireland's Curlew Conservation Programme, initiated in 2017, deploys wardens for nest monitoring, habitat enhancement, and feeding site creation, identifying key breeding and foraging areas across 20 sites. Headstarting programs, involving captive rearing of chicks for release, have been implemented for Eurasian Curlews in multiple European sites, with GPS tracking revealing a 42% survival rate from release to migration, though predation accounts for most early mortality within the first week. In , initiatives for Long-billed Curlews include solar-powered tagging to map migration routes from breeding grounds in states like and , informing habitat connectivity on working lands, and targeted incentives under the U.S. to maintain prairie grasslands. Outcomes show localized improvements but persistent global challenges. The Irish programme reported higher breeding pair detections in managed areas by 2023, yet emphasized that scaling efforts is essential for reversal, as populations remain unstable. UK moorland projects incorporating predator control and minimized disturbance have boosted chick survival in trials, though national declines continue at rates of 30-49% over three generations in Europe. For Long-billed Curlews, tracking has revealed cryptic subpopulations, aiding targeted protection, but the species was reassessed as Threatened in Canada in 2024 due to ongoing habitat fragmentation. The 2025 IUCN declaration of the Slender-billed Curlew (N. tenuirostris) as extinct highlights failures in historical efforts, with no confirmed sightings since 2001 despite searches, attributing loss to wetland drainage and hunting.

References

  1. https://www.inaturalist.org/taxa/3894-Numenius
  2. https://earthlife.net/curlews/
  3. https://www.rspb.org.uk/birds-and-wildlife/curlew
  4. https://www.allaboutbirds.org/guide/Long-billed_Curlew/overview
  5. https://www.bto.org/learn/about-birds/birdfacts/curlew
  6. https://datazone.birdlife.org/species/factsheet/slender-billed-curlew-numenius-tenuirostris
  7. https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/long-billed-curlew-2024.html
  8. https://conservewildlifenj.org/?species=numenius-phaeopus
  9. https://www.worldbirdnames.com/bird/eskimo-curlew/6200.html
  10. https://avibase.bsc-eoc.org/species.jsp?avibaseid=3BB5CBA66CF48884
  11. https://www.merriam-webster.com/dictionary/Numenius
  12. https://pubmed.ncbi.nlm.nih.gov/36451965/
  13. https://pubmed.ncbi.nlm.nih.gov/30968730/
  14. https://www.worldatlas.com/articles/the-eight-species-of-curlews.html
  15. https://birdsoftheworld.org/bow/species/lobcur/cur/systematics
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