Migration of the Curlew Sandpiper Calidris ferruginea through Bulgaria

Bulgaria lies along one of the main flyways of the Curlew Sandpiper between the breeding areas in the Asian tundra and the African nonbreeding areas. The species was recorded at 40 sites in Bulgaria, with the largest concentrations at hypersaline lakes along the Bulgarian Black Sea coast (Atanasovo and Pomorie Lakes), where birds feed on invertebrates, primarily brine shrimps. Northward migration begins with small numbers in the second half of March and in April, with peak passage in May. Stopovers are short, and departures are in a northeasterly direction. Some hundreds of individuals remain in Bulgaria during the breeding season. Southward migrations starts in the second half of July and continues till nearly the end of November; most passage is from mid-July to mid-September. The mean stopover duration is eight days and departure direction is to the southwest. The Bulgarian reservoirs, which are south of the 0°C isotherm in January, have maximum concentrations of 900 birds during the nonbreeding season. Birds ringed in South Africa, Tunisia, the Balearic Islands and southern Ukraine have been recorded in Bulgaria, and birds ringed in Bulgaria have moved to Egypt and Guinea-Bissau. The Bulgarian Black Sea lakes (together with wetlands in Romanian Dobrudja, the Ukrainian Black Sea coast and Greece) are part of a chain of important stopover and refuelling areas for migrant waders. The Curlew Sandpiper is a specialised species and potentially vulnerable to modification of habitats.