Greenfinch (Carduelis chloris) Science Article 3
This paper examines the effect of sex and ring colour on the frequency of removal of plastic colour rings by Greenfinches Carduelis chloris. Of 55 recaptures of 42 individuals, 22 (40%) had lost at least one of its colour rings. Females showed a tendency to remove colour rings more frequently than males. For both sexes, there was a similar tendency to remove more dark than light-coloured rings. While it is not possible to identify a specific reason why the birds remove their colour rings, it is possible that discomfort on the nest may play a role in ring removal by females and, more speculatively, it is possible that males might remove colour rings to manipulate their sexual attractiveness to females. Wrap-around rings might provide a solution to the problem of colour-ringing species with powerful beaks.
Ziemowit Kosinski, Ringing & Migration (2004) 22, 4-6