Colour bands, mate choice and paternity in the bluethroat

Studies of several bird species have shown that coloured leg bands may affect a male's success in mate attraction and/or mating competition. From a colour band experiment in the field, we have previously reported that male bluethroats, Luscinia s. svecica, with blue and orange bands (BO males) guarded their mates less intensely at the peak of female fertility, and spent more time advertising for additional mates, than males banded with non-BO colours. These responses indicated that BO males experienced less threat to their paternity than did non-BO males, possibly mediated through an increased attractiveness. Here we present paternity analyses of the broods from the field study and test whether there were differences between the two male groups in within-pair or extrapair paternity. There were no significant differences between the two groups of males in paternity, suggesting effective male protection of paternity. However, extrapair paternity was infrequent in the 2 years of the field experiment; hence, the power in detecting effects on paternity does not allow a definitive conclusion on this issue. We also conducted an aviary experiment in which females were given the choice between a BO male and a non-BO male, to test whether females had preferences for particular colour bands. Females did not associate more with BO males, as would have been expected if these males were more attractive in social mate choice. Our results suggest that the effects of colour bands on social mate choice and paternity are, at best, weak. Copyright 2000 The Association for the Study of Animal Behaviour.