Parents raise higher proportion of high quality recruits from low fledgling production in the local population of tawny owls, Strix aluco

Abstract. The effects of weather and individual attributes of the broods in the local population of tawny owl Strix aluco on recruitment were studied in the Duna-Ipoly National Park, Hungary (47°35′ N; 19°02′ E) in 1992–2007. In harsh breeding conditions, with many snowy days, the parents' body condition was low and they were able to raise only few fledglings. Nevertheless, the few fledglings remaining in this reduced broods left them in better condition and had a greater chance to be recruits than offspring which fledged in mild seasons, with many siblings, from broods raised by the parents in good condition. Parents produced most male recruits in adverse breeding seasons, when one offspring fledged from the broods, but raised most female recruits in mild breeding years, when two offspring left the broods. Sex related differences in the recruitment of a local population of tawny owls are discussed with a focus on environmental effects.