Slender-billed Curlew (Numenius tenuirostris)

[order] CHARADRIIFORMES | [family] Scolopacidae | [latin] Numenius tenuirostris | [UK] Slender-billed Curlew | [FR] Courlis a bec grele | [DE] Dunnschnabel-Brachvogel | [ES] Zarapito Fino | [NL] Dunbekwulp

Subspecies

Physical charateristics

Very pale curlew, with shortish, slim, pointed bill.
White or pale buff ground color of head, neck and breast. Lower back, rump, undertail and underwing white. Uppertail coverts white with sparse brown markings. Typically has rounded or heart shaped dark markings on breast and flanks.
Similar to N. phaeopus, but paler, lacks dark crown stripe. Female averages larger with longer bill. Non-breeding adult has fewer marks on flanks.

Range

Eurasia : Central

Habitat

On migration a wide variety of habitats is used, including saltmarsh, steppe grassland, fishponds, saltpans and brackish lagoons. There is a similar degree of variation in the known wintering habitats, with some records from tidal mudflats (Tunisia), others from semi-desert “sebkhets” (temporary brackish wetlands in Tunisia and Algeria), and others from brackish marsh and sandy farmland (such as at Merja Zerga). In view of the species’ rather broad choice of habitat on passage and in winter, it is unlikely that habitat loss in these areas has played a major part in the decline (particularly since many other wader species using the same region have not suffered such a decline). Loss of breeding-ground habitat, which may be much more specialised, would better explain such a drastic collapse. It has been argued (e.g. by Belik 1994) that the species may nest primarily in steppe areas; if so, then the massive loss of such habitat (notably in Kazakhstan) may have played a part in its decline.

Reproduction

Little detailed information can be given on breeding ecology and behaviour, since the only confirmed observations come from just one site at least 70 years ago. This site, near Tara, is close to the northern limit of the forest-steppe zone. The habitat appeared largely unchanged during surveys in 1990 and 1994, and was closer to a taiga marsh than a typical forest-steppe marsh. It is possible that the habitat at this site was not typical of that used by the species, and thus the species may nest further north (in true taiga habitat) or south (in steppe habitat).

In May 1914 a single Slender-billed Curlew nest was found, with four eggs (Eurasian Curlews were also nesting nearby). In 1924 a colony of the species was found, containing 14 nests (within a few meters of each other), at the same site south of Tara. With so few observations there is no way of knowing how common such colonial nesting is. Eggs were found in May. Apparently breeds in small colonies, with nests 2-3 m apart. Nest in dense growth on dry areas within bogs, constructed of dry grass. 4 eggs(?).

Feeding habits

There is little information available on diet. The birds at Merja Zerga have been recorded taking earthworms and tipulid larvae, while elsewhere other insects (grasshoppers, an earwig and a beetle), molluscs and crustaceans have been recorded as prey. The most detailed observations of foraging behaviour have been made in recent years at Merja Zerga where the species uses two contrasting habitats, brackish grazing marsh and sandy agricultural land on higher ground nearby. In both areas the birds often feed with Eurasian Curlews and the feeding behaviour is broadly similar to that species: the birds walk slowly, occasionally pecking at the surface or probing the soil; if a food item is located, intensive probing results, until the item is extracted. On average 1.5-2.75 food items were obtained per minute, and feeding was concentrated in mid-morning and mid-afternoon, with the birds roosting in the lagoon at other times.

Conservation

There are very few recent records of this species and sightings have become more and more infrequent, presumably as a result of declines caused by habitat loss and exploitation. No regular breeding, passage or wintering population is known, and the number of remaining individuals must be tiny. For these reasons the species qualifies as Critically Endangered.

Migration

Migratory. Few recent observations anywhere due to growing rarity. In 19th century, when numbers larger, part of population migrated south across Turkmenistan and south Caspian to winter in Iran and Iraq, while others passed SW-WSW across Transcaucasia, Ukraine, Balkans (extending into south-east Hungary), and Italy (including Sicily), to winter in North Africa, especially in Maghreb. Stragglers then occurred across Europe, exceptionally north to Baltic and west to Low Countries and Atlantic coast of France.
Passage still occurs across Aral-Caspian steppes, Turkmenistan, and Ukraine, and recently reported Iran (38 in 1990, 21 in 1992, 15 in 1993). A few still migrate across Turkey, Balkans, and southern Hungary August-November and March-May, and occasionally occur December-February. Flock of up to 19 birds south-east of Italy January-March 1995. No modern records from Egypt or Libya, but several recent December-February reports from Tunisia. Morocco probably now the main wintering area for the species; recent records mainly November-March.

Distribution map