Abstract:

To find better mating opportunities may be one of the reasons why birds disperse from one population to another, although evidence is scarce to prove this proposition. Penduline Tit is a highly suitable model species to clarify this question, since both males and females may have several mates during a single breeding season. We followed the dispersal of Penduline Tits in a system consisting of six populations. Our study provided evidence for short distance within-season breeding dispersal in Penduline Tit between our study sites. Both the rate of immigration and emigration showed a strong seasonal pattern, which may be related to the fluctuation in mating opportunities. The number of immigrating males increases with the number of unmated females in the population, i.e. mating opportunities of males. Furthermore, the number of unmated males (mating opportunities of females) in the population increased with the number of immigrating males. Our results thus indicate a relationship between dispersal behaviour and mating opportunities in Penduline Tits. Further studies are needed to distinguish between cause and effect.