COOPERATIVE DEFENSE AND INTRASEXUAL AGGRESSION IN SCOPS OWLS (OTUS-SCOPS) - RESPONSES TO PLAYBACK OF MALE AND FEMALE CALLS

We tested 11 male Scops Owls (Otus scops) and their mates with the pla yback of conspecific male and female calls to determine whether their response to intruders differed according to the sex of the intruder. E ight measures of response intensity were recorded for each owl. Territ orial defense appeared to be strictly cooperative with both members of a pair reacting to intruders of either sex. Males responded more stro ngly to male playbacks for five measures of response intensity indicat ing that males are more aggressive toward intruding males. Females als o showed a tendency to respond stronger to female playbacks, bur, over all, both sexes showed little reaction to female calls. This may provi de a mechanism for polygyny in this species.