Alimentación de Turdus philomelos en los olivares mediterráneos ibéricos, durante la migración otoñal

Resum

Feeding habits of the Song Thrush (Turdus philomelos) in the Iberic mediterranean olive groves, during its autumnal migration
The gastric contents of 92 Song Thrushes caught in Majorca (n = 47) and Montsia (n = 45) during October 1986 have been analyzed. Diet composition is-given for taxonomic and typological prey-types. Song Thrushes of Majorca consumed high quality resources homogeneously, whereas those of Montsia used suboptimal resources heterogeneously. Trofic differences found between ecomorphotypes need further estudies to be adequately interpreted. The energy conversion of prey types clearly show that olives are the molt song thrushes’ profitable prey. The need of animal prey consumption related to proteine deficit and the alternative coevolutive hypothesis are discussed. Estimations of the costs of Song Thrush feeding activity during the winter to olive harvest are given.