COMPARISON OF DIET IN COLLARED FLYCATCHER (FICEDULA-ALBICOLLIS) AND PIED FLYCATCHER (FICEDULA-HYPOLEUCA) NESTLINGS IN A HYBRID ZONE

A comparison of collared (Ficedula albicollis) and pied flycatcher (Fi cedula hypoleuca) diet was conducted on the basis of simultaneous samp ling of nestling diet taken by the ligature method in oak-beech forest s in central Moravia. Diet in the collared flycatcher contained 657 pr ey items and that of the pied flycatcher 747. No difference in average body length of prey was found. Differences were found in diet composi tion, both in total and during sunny and rainy periods. In total, the diet of the collared flycatcher contained more Coleoptera and Heteropt era and less Diptera. The collared flycatcher compensated for reduced intake of Araneida, Bibionidae and Coleoptera during rainy periods, wi th an increased uptake of Formicidae, whereas the pied flycatcher hunt ed more Formicidae, Heteroptera, Limoniidae and Syrphidae. The results show that species specific prey selection and responses to changing p rey availability can reduce food competition during nestling period.