High voltage pylons as roost sites of the Lesser Kestrel (Falco naumanni) during the pre-migratory period in the Southeastern Balkans

Abstract

Although the Lesser Kestrel (Falco naumanni, Fleischer, 1818) was a widespread species in Bulgaria, there are no detailed surveys on its biology and ecology like the ones implemented in countries still harbouring abundant populations, such as Spain, Italy, Greece, etc. After 2014 when “Green Balkans”, as a breeder, launched the reinforcement of the species and its recovery in Bulgaria now it is possible to study the species using modern technologies and methods like radio and satellite transmitters. The known roost sites (n=12), the subject of our study, are located from 55 to 745 m above the sea level, as the main part of them is situated about 100 - 200 m above the sea level. The most numerous roost site, which is located in the North-eastern Greece, is comprised of about 80 individuals but in the other roost sites the number of the Lesser Kestrel reach 20-40 individuals. During the period 2014 - 2021 the Lesser Kestrels in the largest known colony of the species in Bulgaria, which is located in SPA Sakar, have used different high voltage pylons from the same power lines, alternating pylons depending on the type of agricultural crops in the area. It has been found that the birds express preferences for cereal crops around high voltage pylons, which they use as roost sites. Keywords: communal roost sites, LIFE for Lesser Kestrel, post-breeding dispersal.