River Warbler
Locustella fluviatilis ( Wolf, 1810)
Order Passeriformes
Family Sylviidae
Conservation status: in Bulgaria: Vulnerable VU B1c+D1, BDA-III; International: IUCN-LC,BeC-II, BoC-II.
General distribution. A Palearctic species whose breeding area is from Denmark and Germany in the east to the upper reaches of the river Ob in Northern Kazakhstan. In recent years an expansion of the area to the south has been registered. It winters in the tropical part of Eastern Africa.
Distribution and abundance in Bulgaria. A breeding summer visitor and passage migrant. It was registered for the first time in the country in the middle of the 20th century [1, 2, 3, 4], and as breeding in 1980 [5]. It was found along the Danube (Belene Island, the fish farms Mechka and Nova Cherna, Garvansko Swamp and Srebarna Reserve) and the Black Sea coast (the lakes Durankulak, Vaya, Atanasovsko), in the Sofia field and in the valleys of the rivers Struma, Maritsa (the fish farms near Trivoditsi), Arda and Tundzha; a total of 9 breeding habitats are known, with about 60 pairs [6]. According to other data [7], its modern breeding distribution is exclusively along the Danube, with total numbers between 130 and 530 pairs.
Habitats. Flooded island forests along the Danube, environs of reed associations in different types of natural and artificial wetlands.
Biology. It incubates twice in the year singularly or in groups of up to 5 pairs at a distance of 50-100 m [6]. The nest is located on the ground amongst thick vegetation. It lays 4-7 eggs. The food consists of insects.
Similar species. Savi's warbler (Locustella luscinioides), the Grasshopper Warbler(Locustella naevia).
Negative factors. Unstudied.
Conservation measures taken. Protected according to the Biological Diversity Act. A large part of the breeding places are within Protected Territories.
Conservation measures needed. A more detailed study of the breeding distribution and the dynamic of the numbers.
References. 1. Mauersberger, 1960; 2. Donchev & Undzhiyan, 1961; 3. Paspaleva-Antonova, 1961; 4. Donchev, 1964; 5. Michev & Vatev, 1983; 6. Nankinov, 2000; 7. Iankov, in press.
Authors: Tanyo Michev, Pavel Zehtindzhiev, Iliya Vatev
