Falco vespertinus (Linnaeus, 1766)
Erythropus vespertinus (L.): Elwes, Buckley, 1870: 75; Reiser, 1894: 107; Prostov, 1964: 41.
Conservation status: in Bulgaria: Critically endangered CR = E, BDA-II, III; International: IUCN-NT, CITES-II, BeC-II, BoC-II, ECS-Spec 3, BD-I.
General distribution. A Palearctic polytypical species with two subspecies. The major area of the subspecies Falco vespertinus vespertinus embraces Europe in the east to lake Baikal. The total number of the European population is estimated at 26 000 – 39 000 breeding pairs [1, 2, 3].
Distribution and abundance in Bulgaria. A breeding summer visitor and passage migrant. At the end of the 19th century, only one breeding habitat was known, near the city of Yambol (Reiser, 1894). Later, singular birds or pairs were also found in the regions of Sofia, Lovech, Razgrad and Varna (Jordans, 1940; Arabadzhiev, 1962; Simeonov et al, 1990). In the last 25 years, it was found breeding near the towns of Shabla, Durankulak, Kaliakra and in Dobrudzha [4, 5, 6] and in the valley of the Danube (mainly Zlatiyata) . New breeding colonies have been registered along the valley of the Arda River and the Svetiiliyski Vazvisheniya (hills), where 1-4 pairs bred every year in the period 1998-2004 . The total breeding population in the country is estimated at 150 – 250 pairs , 160-200 pairs according to other assessments . The data given are obviously exaggerated, as in 2005 and 2006, in a focused search throughout country, only one breeding pair was found (E. Todorov, personal communication).
Habitats. Open spaces near agricultural areas, field-protecting belts and other forest plantations.
Biology. It breeds colonially from the middle of May in field-protecting belts of Acacia, Ash trees, etc. It uses old nests of Magpies and Rooks. The full clutch consists of 3-4 eggs. The young ones fly away after 26-28 days. It migrates from the end of April and the beginning of May. The autumn migration is during the second half of September to the beginning of October, whereby in Europe it is only over Burgas where real concentrations are observed (up to 3 110 individuals were reported for 1989, with a daily maximum of 1 200 individuals on 20 September 1998) . The food range includes mainly Mole crickets, dragonflies, crickets, beetles, lizards, small mammals .
Similar species. The Hobby Falco subbuteo (Linnaeus, 1758).
Negative factors. Use of semi-steppe regions for intensive agricultural production, illegal shooting and wood production in the field-protecting belts.
Conservation measures taken. Protected species since 1962, included in the Red Data Book of Bulgaria (1985) . Intensive studies were carried out on its autumn migration in the region of Burgas Bay . Plans for the management of the reserves Srebarna, Atanasovsko Ezero and Kaliakra, as well as for the lakes Durankulak and Shabla have been prepared and are being implemented. In 2006, the execution of a project for its detailed study was launched.
Conservation measures needed. Study of the factors for the failure of the breeding population in the country; urgent preparation of a National Plan for its preservation; provision of protection for the nests, placing bird houses, increasing the ecological culture of the population.
References. 1. Simeonov et al., 1990; 2.Cramp and Simmons (eds.), 1977; 3. BirdLife International 2004; 4. Dereliev, S et al., 1997a; 5. Dereliev, S et al., 1997 b; 6. Profirov, Ivanov. 1997. 7. BSPB, in press; 8. Nankinov et al., 2004; 9. Michev et al., 2004; 10. Nankinov, 1985.
Authors: Lyubomir Profirov, Pavel Simeonov, Ivaylo Angelov