ИСТИНА

We investigated the energetic cost of advertising behaviour (AB) of free-living Pied Flycatcher males occupying nestboxes in the pre-breeding period. AB of bachelor males was recorded by metronomic timekeeping and their basal metabolic rate (BMR) was measured at night time. Males differed in the ratio of time spent on singing and flight activities. This ratio was influenced by male colour type and habitat fragmentation. The rates of singing and flights were negatively related. Mass specific BMR was positively related to daily energetic cost of AB which was mainly influenced by time spent on such expensive activities as flights. At the same time, BMR was negatively related to song rate. The results suggest that the use of an expensive advertising strategy is accompanied by the need for an increased BMR in this species.