“…Tits, especially the Great Tit Parus major and the Blue Tit specialise in exploiting caterpillars as the most profitable food for their nestlings (Blondel et al 1991, Perrins 1991, Bańbura et al 1999. Caterpillars contain a balanced proportion of essential nutrients and water necessary for tit nestling development and, in addition, their sizes and physical form are suitable for easy swallowing by nestlings (Perrins 1991, Zandt 1997, Bańbura et al 1999.…”