RANDOM SETTLEMENT OF FEMALE PIED FLYCATCHERS, FICEDULA-HYPOLEUCA - SIGNIFICANCE OF MALE TERRITORY SIZE

In a study of the pied flycatcher the availability of nest sites, and hence the territory size of males, was manipulated. The number of females that a male attracted was positively correlated with his territory size; males in a low-density plot attracted more females than males in a high-density plot. A partial correlation analysis showed that territory size was the single most important determinant of male mating success, at least late in the season. If females actively choose between males on the basis of territory size or male density, males in the low-density plot should be preferred over those in the high-density plot. However, the relative number of females settling in the plots was the same before and after manipulation of male density. The results are consistent with an hypothesis of random female settlement where females arrive randomly in relation to area and mate with the first male they encounter. It is argued that when females are constrained by time and energy, random settlement is the best pairing strategy they can adopt, as high-quality males in high-quality territories are most likely to be detected by prospecting females. The results suggest that male pied flycatchers defend territories to gain access to females. © 1990.