Bioacoustics of Ficedula hypoleuca

Furthermore, F. h. iberiae is considered an intermediate between nominate hypoleuca and speculigera . Some recent works treat speculigera as a separate species, but without confronting the problem with iberiae ( e.g. , Saetre et al . 2001 ; Corso et al . 2015 ). Potti et al . (2016) distinguished speculigera and iberiae as species based on statistical differences in morphological traits, but without a comparison with type material and topotypes, and no deposition of vouchers nor the required comparison with nominate hypoleuca . Moreover, these authors, echoing Curio (1960) , suggested that speculigera and iberiae were more closely related to each other than to hypoleuca , but did not expressly compare them to the latter. Further factors, still partly related to hybridiZation, might also come into play. First, these birds are migrants, implying that their populations are philopatric in their breeding. This may drive differentiation between the nuclei of the populations, even if the populations hybridiZe at the periphery. Secondly, despite males being morphologically diagnosable, females are not. Accordingly, song and behavior, which are less studied characters than plumage, might have a more prominent role in delimiting subspecies. For instance, Robb & The Sound Approach (2015) attempted differentiating nominate hypoleuca from iberiae and speculigera by song, with a reasonable degree of success. There are two species considered to be closely related to F. hypoleuca , namely the Collared Flycatcher F. albicollis (Temminck) , known to hybridiZe with F. hypoleuca ( e.g. , Qvarnström et al . 2010 ; Saetre & Saether 2010 ), and the Semicollared Flycatcher F. semitorquata (Homeyer) ; the latter is often considered a subspecies of the former in the literature ( e.g. , Mayr & Cottrell 1986 ; Cramp & Perrins 1993 ). These three species have an as yetunresolved evolutionary history, having diverged around 1–2 Ma ago ( Lundberg & Alatalo 1992 ; Nadachowska- BrZyska et al . 2016). Both F. albicollis and F. semitorquata have long been accepted as distinct species from F. hypoleuca ( e.g. , Dunajewski 1938 ; del Hoyo et al . 2006 ; Uebbing et al . 2016 ). However, some authors consider F. semitorquata a subspecies of F. hypoleuca ( e.g. , Hartert 1907 ; Lundberg & Alatalo 1992 ) and F. h. speculigera an intermediate between F. h. hypoleuca and F. albicollis ( e.g. , Corso et al . 2015 ). Consequently, any thorough systematic work dealing with the circumscription of F. hypoleuca should include the relationships and status of these taxa as well.