Phylloscopus sp., possible hybrid P. collybita × P. ibericus

Passeriformes – Phylloscopidae

CZEP18-461

Sex: M, age: 1CY+ (euring: 4), trapped: July, 2018 in Vysočina Region, Czech Republic

A rather interesting individual found by a birder in Czechia which was showing some marks typical for Iberian Chiffchaff (Phylloscopus ibericus), especially the song which contained syllables of an Iberian Chiffchaff as well as those of a Common Chiffchaff (P. collybita). It was later excelently documented by Jan Studecký (see his outstanding video recording on youtube ). We were then asked to trap it and perform genetical analysis. We analysed part of its mitochondrial DNA and were surprised to find out it's a Common Chiffchaff. The bird seemed clearly different in hand. We searched literature to find out if it is possible to identify a hybrid of Iberian Chiffchaff and Common Chiffchaff (as hybrids are reasonably common where these two overlap) but, unfortunatelly, with current knowledge, we were unable to identify it without any doubt. We could try to design our own genetic markers but that is currently way too expensive for a curious birders. Maybe we will be able to go back to this bird in the future. The bird was apparently paired with a female Common Chiffchaff and there were four nestlings in its presumed nest.