MALE AND FEMALE BEHAVIOR AND EXTRA-PAIR PATERNITY IN THE WHEATEAR

Behavioural observations and DNA fingerprinting were used to determine the relationship between male and female behaviours and levels of ext ra-pair paternity in the wheatear, Oenanthe oenanthe. Behavioural obse rvations were consistent with the hypothesis that males attempted to e nsure paternity by mate guarding, while pursuing extra-pair copulation s (EPCs) primarily outside the fertile period of their pair female. Th e intensity of guarding varied with time of season and was greater at late nests. However, although males on territories with late nests als o experienced high intrusion rates, the intensity of guarding was infl uenced more by the operational sex ratio (which was female skewed at e arly nests) than by intrusion rates per se. We suggest that early bree ding males adopted a strategy of territorial defence to ensure paterni ty, as opposed to guarding their female directly (which late breeding males did), to capitalize on the increased opportunities to pursue EPC s in neighbouring territories. Females were less conspicuous than male s in their pursuit of EPCs, were never seen off territory or observed to solicit extra-pair males directly, and rejected the majority of EPC s. The frequency of extra-pair paternity was 11% of 73 offspring, in 2 9% of 17 broods, and was not correlated with the intensity of guarding . Female cooperation appeared to be important for successful copulatio n, and extra-pair paternity is therefore likely to be a consequence of solicited, or at least accepted, EPCs. We discuss why females might h ave participated in EPCs. (C) 1998 The Association for the Study of An imal Behaviour.