COORDINATION OF FEMALE NEST ATTENTIVENESS WITH MALE SONG OUTPUT IN THE CAVITY-NESTING HOUSE WREN TROGLODYTES-AEDON

During the incubation stage of breeding, male House Wrens periodically move very near nest cavities and sing, and females, who alone incubat e in this species, often appear to wait to take a break from incubatin g until they hear their mate singing nearby. This study tested quantit atively for a non-random association between female nest attentiveness and male song output in two ways. First, 11 pairs of wrens were obser ved for 2 h during their incubation stages and the rime of each male s ong and each female exit from, and entrance into, the nest cavity was noted. Of the 60 exits observed, 29 (48%) occurred within 30 s of when the male began a song bout near the nest. Overall, female exits follo wed significantly sooner after the start of male song bouts than expec ted if exits normally occurred al random with respect to song. Males w ere also removed temporarily from 12 territories during incubation sta ges and the nest attentiveness of their females was monitored for 2 h. These experimental females spent, on average, 18% more time in nests than did 11 undisturbed control females (47 vs 40 min/h). This occurre d only because experimental females waited longer to exit nests during each attentive period. Experimental females did not take shorter rece sses. Females may benefit from waiting to exit nests until their mates are singing nearby because: (1) the male's song indicates to the fema le that no predators are present, (2) males will be present to guard n ests, especially against conspecifics, in the female's absence, and/or (3) males can act as sentinels while females are foraging.