Dj. Ziolkowski et al., COORDINATION OF FEMALE NEST ATTENTIVENESS WITH MALE SONG OUTPUT IN THE CAVITY-NESTING HOUSE WREN TROGLODYTES-AEDON, Journal of avian biology, 28(1), 1997, pp. 9-14
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.