Had been observing male & female Pied Wagtails bring food to a nest in our wood store, until last Sunday (19Jul15) the male appeared to have lost his tail feathers. He nevertheless continued to bring food to the nest and remove faecal pellets.
Astonished then to see another male do the same (tail intact) and the female. So, three adults, two male and one female tending the same nestlings (assuming "stumpie" was a full adult; or could he have been from an earlier brood of the same parents?).
Seem to have fledged this week (as now all quiet - I've been away, so I missed the first emergence (or predation!)).
Explanations, of what I assume is pretty unusual behaviour, gratefully received.
If both of the fathers are recognisably male due to having black backs then they must be adults (young birds will be pale grey-backed until the post juvenile moult in autumn).
Mixed pairings like this occur in several species (infamously - the dunnock) and such behaviour is probably overlooked. During research on farmland birds, I've seen at least three cases of female yellowhammers rearing broods with the help of more than one male: two nests with two males and one with three! I've watched a couple more nests where I could not prove this was happening, but where the rate of nest visits was way too high for just two parents.
In the case of yellowhammers, the females appear to recruit extra help by soliciting copulations from multiple males, even when she is not laying eggs. Presumably this tricks the extra males into thinking that they have a genetic investment in the broods. In contrast, cirl bunting females only copulated during egg laying and we never saw a single instance of polyandry.
