TEMPORAL PATTERNS OF WITHIN-PAIR COPULATIONS, MALE MATE-GUARDING, ANDEXTRA-PAIR EVENTS IN EASTERN RED-WINGED BLACKBIRDS (AGELAIUS-PHOENICEUS)

I studied the timing of within-pair and extra-pair behaviors in an eas tern population of red-winged blackbirds. Within-pair activity was hig hest several days before egg-laying started and during the morning and evening hours. Extra-pair events also peaked just before egg-laying b ut showed no distinct diurnal pattern. Red-winged blackbird pairs on a verage copulated 21-22 times per clutch. Males followed their females more than the reverse, but spent only a third of the time within 10 m of their mates. Male presence on the territory deterred potential extr a-pair events, and although males were on their territories for 94% of their day, they did leave, apparently to forage, on occasion. Extra-p air events involving these males' females were more likely during thes e departures than expected by chance. Apparently as a consequence, mal es went on fewer forays when their female was most fertilizable. Males did not copulate with their females more often than normal just befor e or after forays or intrusions. Pairs that copulated more often had f ewer extra-pair fertilizations in their broods, but no other behaviors were correlated with paternity. These results have several important implications for understanding the effects of sperm competition of mat ing and parental behavior.