Acrocephalus agricola (Jerdon, 1845)
Order Passeriformes
Family Sylviidae
Conservation status: in Bulgaria: Endangered EN=C [2(a(i))], BDA-III.
General distribution. A Palearctic species, whose range extends from Southeastern Europe in the east to the coast of the Sea of Okhotsk and Manchuria; in the north it reaches Southwestern Siberia, and in the south – Turkey, the foot of the Great Caucasus Mountains, Iran, Tadzhikistan, Afganistan, Kazakhstan, Mongolia and China.
Distribution and abundance in Bulgaria. A breeding summer visitor with breeding localities only along the Black Sea coast. Since its finding in the country in 1968 near Shabla Lake [1], there have been comparatively few observations [2]. At present the largest numbers during the breeding season have been registered in Durankulak Lake: 40-100 pairs [3, 4, 5, 6], Shabla Lake – about 10 pairs [7, 8] and Shablenska Tuzla lake [2]. There are data about an expansion of its range along the Southern Black Sea coast: Atanasovsko Ezero lake [4, 7], Alepu Marsh [4] and Dyavolsko Marsh [4]. The numbers during the breeding period in the country varies widely: 60-200 pairs [4, P. Zehtindjiev , B. Nikolov, unpubl. data].
Habitats. Reedbeds in shore salty, brackish or freshwater lakes and lagoons [8].
Biology. In Bulgaria it is almost unstudied. It probably has or even second clutches, as neslings have been registered both in the middle of June (Durankulak Lake) and in the middle of July (Shablenska Tuzla lake) [2, 3]. Nest building has been observed only with females birds of a pair in Durankulak Lake on 16 May [6]. In the population from the same lake, a large genetic variety has been registered [Zehtindjiev, Bensch, unpubl. data]. The low percentage of recovored ringed birds of that population found in the last three years also points to the large inflow of immigrants determining the numbers of birds breeding in Bulgaria [5].
Similar species. None.
Negative factors. Unknown, most probably of inter-species reasons (a greatly restricted distribution).
Conservation measures taken. Protected according to the Biological Diversity Act. Almost all the breeding places are included in protected areas and sites of the Ramsar Convention. A study of the genetic structure and the blood parasites of the birds of the population in Durankulak Lake is being carried out.
Conservation measures needed. Study of the numbers and the area of the populations, the biology and the ecology of the species; study of the genetic variety of the Bulgarian population, the processes of migration and exchange of genetic material in it and between the separate populations within the species' range.
References. 1. Donchev, 1970; 2. Otto, 1984; 3. Nadler, Ihle, 1988; 4. Nankinov, 2002a; 5. Dontchev, Serebryakov, 1997; 6. Ivanov, 1998; 7. Michev et al., 2004; 8. Cramp, Brooks, 1992.
Authors: Pavel Zehtindjiev, Boris Nikolov