Eurasian Curlew

The Eurasian curlew (Numenius arquata) is one of the largest waders in Europe, recognised immediately by its very long, evenly downcurved bill and streaked brown plumage. Adults are about 50–60 cm long with a wingspan of roughly 89–106 cm, and females average larger than males with especially long bills.

The similar whimbrel (Numenius phaeopus) is smaller and shorter-billed, with a more strongly patterned head and a pale central crown stripe. In flight, Eurasian curlews show a white wedge on the lower back and rump. Their far-carrying bubbling display call is one of the characteristic sounds of open breeding landscapes in spring.

Breeding Eurasian curlews use open landscapes including wet and semi-natural grassland, moorland, peatland, heath and agricultural fields. After breeding, many move to estuaries, tidal mudflats, saltmarshes, coastal grassland and nearby farmland, where rich intertidal feeding areas can support large winter concentrations.

The species therefore depends on very different habitats during different parts of the year, making both inland breeding landscapes and coastal stopover and wintering sites important.

Eurasian curlews feed mainly on invertebrates. Earthworms, insects, marine worms, molluscs and crustaceans form most of the diet, while plant material and small vertebrates are taken occasionally. Insects are particularly important on inland breeding grounds, whereas coastal birds exploit a broader range of marine prey.

The long, downcurved bill is a specialised feeding tool. Curlews probe deep into soft ground and mud, and the sensitive bill tip can detect pressure and vibrations in the substrate, helping the bird locate hidden prey. The curved shape also lets the tip follow irregular cavities beneath stones and inside burrows where a straight bill is less effective. Surface prey can also be picked directly when it is exposed.

A field experiment at the Taff Estuary in Wales, published in 1994, used models based on real male and female curlew bills. Curved bills reached farther into crab burrows and could rotate more once inserted. The longer female bill reached deeper, while the shorter male bill could rotate more at comparable depths, giving the sexes somewhat different mechanical advantages when probing.

Migration varies across the enormous range. Many birds breeding in western Europe are resident or move only moderate distances, while populations from Fennoscandia, the Baltic region and Russia migrate southwest or south after breeding. Important wintering areas stretch along the Atlantic coasts of western Europe and northwestern Africa and through the Mediterranean, Middle East and southern Asia.

Wintering populations can therefore mix birds from widely separated breeding areas. Britain and Ireland, for example, hold resident curlews as well as large numbers arriving from Fennoscandia. Adults often show strong fidelity to both breeding and wintering areas.

Eurasian curlews nest on the ground in open grassland, moorland, peatland and similar habitats with enough vegetation to conceal the nest while preserving good visibility around it. The nest is a shallow scrape lined with nearby vegetation. Four eggs are typical, and incubation lasts about 27–29 days with both sexes taking part.

The chicks are precocial, meaning they hatch well developed and leave the nest soon afterwards. They find their own food but remain guarded while they grow, normally becoming capable of sustained flight after about 32–38 days. A study published in 2001 from western Finland found that females usually left the brood around 16 days after hatching, while males remained until the young were independent, about 35 days after hatching.

Because the eggs and chicks remain on the ground for several weeks, breeding success is highly sensitive to agricultural operations, disturbance and predation.

The Eurasian curlew is classified as near threatened on the IUCN Red List. It is assessed as Vulnerable in Europe, where many breeding populations have declined substantially.

The species still has a very large Eurasian range, but its conservation status reflects widespread long-term declines rather than a naturally small distribution.

The most important threats are concentrated on the breeding grounds. Loss and degradation of open grassland, peatland and wet farmland, drainage, agricultural intensification, afforestation and development can remove feeding and nesting habitat. Early mowing and other field operations can destroy nests or kill chicks, while predation can cause very low breeding success in some landscapes.

Additional pressures occur elsewhere in the annual cycle. Hunting has affected some migratory populations, and climate change may alter both breeding conditions and the coastal wetlands used during migration and winter.

Conservation focuses on improving breeding success while retaining large, open landscapes with wet feeding areas. Measures include delaying or adapting field operations around active nests, protecting nests from predators, restoring wet grassland and peatland, and targeted predator management where predation is preventing recovery.

The species has also been the subject of an international AEWA action plan, while programmes in the United Kingdom and elsewhere combine monitoring, habitat management, farmer support and protection of key breeding areas. Restrictions on hunting along the flyway are another important part of reducing avoidable adult mortality.