Observations of behaviours in males of a socially monogamous migrant passerine, Northern Wheatear (Oenanthe oenanthe), when attempting to mate outside of their social pair bond.

Instances of males in a normally socially monogamous species seeking an additional partner in a polygynous relationship are well known, yet the courtship behaviours associated with these two scenarios are less well reported. Here we use observations arising out of an ongoing long-term study of Northern Wheatear to demonstrate the different behaviours adopted by males in these two situations, one being more frantic than the other. Furthermore, we report how the occurrence of extra-pair paternity (EPP, offspring that are not solely those of a female’s socially bonded male) appears more widely exhibited in our study population than previously documented.