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- 6 -

PART 1. 

BACKGROUND INFORMATION 

 

The information given below a summary of the available material; see Gretton (1991) for further 



details. 

 

 



Distribution and population 

The only fully confirmed breeding records of the Slender-billed Curlew were made between 

1914 and 1924 near Tara, to the north of Omsk in Siberia (Ushakov 1916, 1925). There are a 

number of historical records of summering birds from elsewhere in south-west Siberia and 

northern Kazakhstan which may refer to breeding birds, though there is no hard evidence of 

nesting. 

 

From the breeding area the main migration route is in a WSW direction, north of the Caspian and 



Black Seas through south-east and southern Europe to north-west Africa. There are also records 

of wintering birds in the Middle East, but because of the low density of observers in much of this 

area it is not clear whether these records represent a second wintering area or whether they refer 

to vagrants. Iran and Iraq may be of particular importance for wintering birds, but unfortunately 

it has been impossible to carry out surveys there in recent years. 

 

The situation in North Africa is also rather unclear at present. Historically this area supported 



considerable numbers of wintering Slender-billed Curlews, with large flocks reported from 

Algeria and Tunisia at the end of the nineteenth century. Indeed the species was described as the 

most common curlew species in Tunisia (Stresemann and Grote 1943) and in Morocco and 

Algeria (Glutz von Blotzheim et al. 1977). As late as the 1960s and 1970s flocks of over 100 

birds were seen in Morocco. In recent years, however, despite increasing interest in the species, 

only one regular wintering site for it has been identified: Merja Zerga in Morocco, which had 

supported just two individuals in the previous two winters but only one during the winter of 

1994-95. There is thus almost as much mystery concerning the current winter quarters as the 

breeding area. During the late 1980s there were claimed observations of 30–90 Slender-billed 

Curlews in Algeria, but unfortunately these records could not be confirmed and have not been 

repeated. 

 

The population of the species was estimated in 1990 to be 80–400 individuals; this may have 



been too optimistic and the estimate was recently reduced to 50–270 birds (see Gretton 1994 for 

the background to this estimate). This estimate is based mainly on the number of passage birds; 

several difficulties exist in producing a population estimate from such data, notably uncertainty 

regarding the proportion of passage birds that are likely to be seen and whether the same birds 

would be seen in different locations. Since 1980, however, there have been (on average) almost 

10 confirmed records of the species per year, involving some 15–22 individuals, and many birds 

are likely to go unseen. Clearly birds are also wintering elsewhere than in the known site in 

Morocco. 

 



 

 

 



- 7 -

Life history 

 

* Breeding 

 

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 (Ushakov 

1916, 1925). This site, near Tara, is close to the northern limit of the forest-steppe zone. 

Ushakov described the habitat as “an extensive quaking peatbog with a dense cover of 

sedge...”, with willow, birch and pine present. 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 Ushakov found a single Slender-billed Curlew nest, with four eggs 



(Eurasian Curlews were also nesting nearby). He shot the female, thus curtailing any 

further observations. Ten years later, however, Ushakov found a colony of the species, 

containing 14 nests (within a few metres 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, but it is notable that Ushakov had not recorded colonial nesting previously. 

 

* Feeding 

 

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 (van den Berg 1988, Gretton 1991) 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. 

 

* Habitat 



requirements 

 

Breeding habitat (as far as it is known) is discussed above. 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. 





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