Present occurrence and habitat selection of the Wood Lark Lullula arborea in SW-Finland

Abstract

The Wood Lark population in SW-Finland crashed at least once during 1960-1993 . This was probably due to the severe winters in South and Central Europe during 1984- 1986. The population recovered from the crash in SW-Finland by the beginning of the 1990s. The population crash of the mid-1980s was reflected in the two Atlas-samples (1974-79 and 1986-89) : the number of Atlas-squares with Wood Larks declined by 29% in Turku-Pori, and by 67% in the whole of Finland. We estimate the size of the Wood Lark population in SW-Finland to be about 400 pairs. We could not confirm the steady decline from the 1940s, which has been reported based on migration counts, probably because observer density and behaviour have changed concurrently . By an analysis of habitat characteristics we show that Wood Larks select their breeding sites carefully . Wood Lark territories were larger and more open than nearby control plots. The number and height of trees, and proportion of deciduous trees also differed between territories and control plots. Based on the same analysis, we estimate that 10- 35% of the suitable sites of the rocky habitat type were vacant in the beginning of the 1990s .