HABITAT DIFFERENCES AND VARIABILITY IN THE LEK MATING SYSTEM OF BLACKGROUSE

Spatially fixed territoriality has been regarded to be a general featu re in lek mating systems. In the absence of territories, however, the nature of leks may change remarkably. We compared leks of black grouse in areas, where territoriality was governed by habitat characteristic s. On ice-covered lakes, where the lekking ground was homogeneous and offered no landmarks by which the displaying males would be able to re cognize territory boundaries, the male aggregations were mobile. 'Clas sical' leks on bogs, however, were stable. It also appeared that on mo bile leks, as compared to stable leks, the opportunities for females t o choose their mates were reduced. The distribution of mating success was more biased in the absence of fixed territories, which may indicat e more intense sexual selection.