Breeding Distribution and Nest Site Diversity of Barn Owl (Tyto Alba) in the Context of Restoration of Agricultural Sector in Central South Bulgaria

The Barn Owl (Tyto alba) bred in 15 UTM squares (75%, n = 20) of the Kazanlak Valley (central south Bulgaria) at 33 localities (55% confirmed, 12% probable and 33% possible breeding). Its distribution in the Valley was found to be five times larger and its population size ten times greater during our study period than previously thought. Evidence of one to five breeding localities (mean 2.2±1.3) was detected in each occupied UTM square. A breeding density of 4.1 bp/100 km2 was close to the average in Central Europe. Nests inside or on metal frames and ducts were typical in the region and gave possibility for its successful breeding in most of the habitable buildings. The Barn Owls were breeding mainly in poorly maintained and abandoned buildings whose supply has not decreased markedly since the agricultural restoration started in Bulgaria after it joined the European Union and intensive industrial agriculture has resumed with EU support. Currently, it appears that Barn Owl is not threatened by a ‘housing shortageʼ over the next decade.