Temporal patterns of within-pair copulations, male mate-guarding, and extra-pair events in eastern red-winged blackbirds (Agelaius phoeniceus)

Within-pair activity was highest several days before egg-laying started and during morning and evening hours. Extra-pair events also peaked just before egg-laying but showed no distinct diurnal pattern. Pairs on average copulated 21-22 times per clutch. Males followed their females more than the reverse, but spent only a third of the time within 10m of their mates. Male presence on the territory deterred potential extra-pair events, and although males' were on their territories for 94% of their day, they did leave, apparently to forage, on occasion. Extra-pair events involving these males, females were more likely during these departures. Apparently as a consequence, males went on fewer forays when their female was most fertilizable. Males did not copulate with their females more often than normal just before or after forays or intrusions. Pairs that copulated more often had fewer extra-pair fertilizations in their broods, but no other behaviours were correlated with paternity. -from Author