Pair bonding in Eurasian Bullfinches Pyrrhula pyrrhula: observations from a colour-ringing study

ABSTRACT A colour-ringing project was used to study pair-bond formation by Eurasian Bullfinches Pyrrhula pyrrhula visiting a garden in northern England. During the period July 2011 to April 2017, 427 Bullfinches were colour ringed, and 235 (55%) resighted at a seed feeder. Thirty-six pairs were identified with both partners carrying a colour ring. There was evidence that some couples might initiate pair-bond formation from as early as November, but most new bonds were first identified from January onwards. The earliest bonds were formed between birds over one year old, and older females appeared to preferentially select older males. Nearly all partnerships continued until the disappearance of one or both birds, consistent with death or dispersal, and for 12 pairs where one bird disappeared the other was subsequently observed to form a new partnership. For two longer-surviving pairs the bond was maintained over two successive breeding seasons (23 and 27 months) and, for another, from winter to winter (13 months). The findings support the previous supposition that the typical breeding strategy for this species is one of bond fidelity until the death of one or both partners, and the subsequent formation of a new bond by the surviving partner. However, there was evidence that three couples had separated and survived to form new partnerships, with the female separating in one case from a bigamous male. The study provides novel information about the pair-bond system of this species.