Published in HBW Volume 15 on page 490.
Original HBW caption:
After pair formation, the male cardueline finch accompanies the female everywhere she goes, guarding her from the attentions of other males. The male is dominant in winter, but becomes subordinate as the breeding season advances. However, in the European Greenfinch (Carduelis chloris), this is often interrupted by outbursts of the “sleeked wings-raised” display by the male, which has a strong aggressive component. This display becomes very much less frequent just before copulation starts. Prior to and during copulation, male finches fluff out their body feathers, as demonstrated by this Black-headed Greenfinch.