THE RELATIONSHIP BETWEEN INDIVIDUAL-DIFFERENCES IN MALE SONG FREQUENCY AND PARENTAL CARE IN BLACKCAPS

Song rates in male blackcaps were examined over the course of the bree ding season and compared with various aspects of mating and later pare ntal behavior in individual birds. Song rates decreased steadily over the breeding season although relative individual rates remained consta nt. Early territory holders sang more and mated faster than late-comer s. Song frequency was positively related to alarm call frequency durin g nesting but negatively related to male incubation and offspring feed ing rates. Surprisingly, under the conditions studied, higher song rat es were indicative of higher nesting success. This demonstrates the po tential role of song frequency in the advertisement of territorial qua lity. There may well be either environmentally dependent differences i n parental care as adaptations to temperature, food or predation press ure or simply a trade-off for males between singing and parental care, where early arriving males derive greater fitness benefits from singi ng, while late arriving males benefit more from engaging in parental c are.