A change of land use is often cited as a causal factor in the decline of many species of farmland birds. Populations of the Little Owl (Athene noctua Scop., 1769) have notably decreased throughout Europe in the last 60 years, including the Czech Republic. The aims of this study were to estimate the recent population trend of the Little Owl and to analyze the importance of altitude and grassland habitat within Little Owl territories. The population trend of the Little Owl in the Czech Republic has still decreasing tendency. The population density dropped from 0.33 breeding pairs (bps) 10 km⁻² to 0.12 bps 10 km⁻² in the first (1993–1995) and second (1998–1999) monitoring program, respectively. The decline is apparent also from results from last Little Owl monitoring program which were carried out in 2005–2006 on 35 study plots (4607 km²). The average population density was estimated at 0.1 bps 10 km⁻². A distinct feature of these recent populations is that they occur in the places with relatively high local density (core areas) in comparison to the surroundings, which are unoccupied. At present, the Little Owl rarely breeds in natural tree cavities, but rather the majority of nesting sites are situated in human artifacts, especially within agricultural objects. Areas in which the Little Owl occurs have a significantly larger proportion of grasslands and are situated at lower altitudes. We suggest that the changes in agricultural landscape associated with disappearance of traditional farming management of grassland habitats, forceful pasturage and regular mowing were the main factors in this long-term population decline. The recent decrease of Little Owls could be also the consequence of the existence of small isolated populations in which mortality is not balanced by immigration from surrounding areas.
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