COPULATION BEHAVIOR AND PATERNITY IN THE CHAFFINCH

We investigated two aspects of sperm competition in a wild population of chaffinches Fringilla coelebs: copulation behavior and genetic pare ntage determined by DNA fingerprinting. Pairs copulated at a high rate before laying, peaking at 4.4 copulation attempts per hour on day -3 relative to laying, with an average of 207 copulation attempts (83 beh aviorally successful) per clutch. Extra-pair copulation attempts (n = 20) made up 7.8% of all copulation attempts that females were involved in. The rate at which pairs copulated was lower during egg-laying, bu t there was no evidence that this was due to the male of the pair timi ng copulations to coincide with an 'insemination window'; it was more likely due to the fact that females solicited copulations at a lower r ate. Both sexes solicited copulations but males solicited mainly extra -pair copulations. DNA finger-printing showed that 17.0% of chicks (n = 47) in 23% of broods (n = 13) were fathered by a male other than the one paired to their mother. There was no evidence of intraspecific br ood parasitism. In three cases where we were able to identify the fath er of extra-pair offspring it proved to be a neighboring male.