Curlews are a group of wading birds belonging to the genus Numenius, recognized by their distinctively long, down-curved bills. These birds are found across various continents, making them a recognizable sight in many coastal and wetland environments globally.
Distinctive Features
Curlews are generally large shorebirds, with the Eurasian Curlew being the largest European wading bird, measuring 50-60 cm in length with an 80-100 cm wingspan. Their most prominent feature is their exceptionally long, slender, and distinctly down-curved bill, which can be up to 20 cm long in species like the Long-billed Curlew. This specialized bill is crucial for foraging, allowing them to probe deep into soft substrates like mud and sand. The bill tip is highly sensitive, packed with nerves that detect pressure and movement, helping the bird locate hidden prey.
Their plumage typically features mottled brown or grey patterns, providing effective camouflage. Curlews also possess long legs, adapted for wading in shallow waters. A characteristic element of their presence is their unique vocalization; the English name “curlew” itself is an imitation of the plaintive “cur-lee” or bubbling calls many species produce. Females often have longer and more curved bills than males.
Ecological Niche
Curlews inhabit diverse environments, including coastal mudflats, estuaries, salt marshes, wet grasslands, and agricultural fields. They are also found in upland moorlands during the breeding season. Their unique bill enables them to probe for a variety of invertebrates such as worms, crabs, molluscs, and shrimp buried in soft substrates. Some species, like the Long-billed Curlew, also consume insects like grasshoppers and beetles found on breeding grounds.
Many curlew species undertake long-distance migrations. For example, some Eurasian Curlews breed in Europe and Asia and winter along the Atlantic coast from North Africa to the North Sea. Long-billed Curlews in North America breed in grasslands and migrate to coastal areas, interior Mexico, or the Gulf Coast for winter. Curlews are often observed foraging individually or in small groups, and outside the breeding season, they may gather in large flocks on tidal mudflats.
Worldwide Species and Status
The genus Numenius includes nine distinct species of curlews. Prominent examples include the Eurasian Curlew (Numenius arquata), widespread across Europe and Asia, and the Long-billed Curlew (Numenius americanus) in North America. Other species include:
- Whimbrel (Numenius phaeopus)
- Bristle-thighed Curlew (Numenius tahitiensis)
- Little Curlew (Numenius minutus)
- Eastern Curlew (Numenius madagascariensis)
Many curlew populations are experiencing significant declines and face various conservation challenges. Habitat loss and fragmentation, driven by intensive agricultural practices, wetland drainage, and afforestation, are major threats. Climate change also poses a risk, with increased rainfall and sea-level rise threatening lowland breeding sites. Predation of eggs and chicks, particularly by foxes and crows, contributes to low breeding success in some areas. The Eurasian Curlew is classified as “Near Threatened” globally by the IUCN. The Slender-billed Curlew (Numenius tenuirostris) is considered critically endangered, and is presumed extinct. The Long-billed Curlew population has also suffered historical declines due to overhunting and habitat loss, with current populations still declining in some areas.