In the French Pyrenees, lek habitats of capercaillie Tetrao urogallus are spatially separated from brood-rearing habitats, which are defended by hens before laying. Spring territories of hens thus determine the placement of leks, which are as near to the geometric centre of the locations of one or more territorial hens as lek habitat allows. The number of cocks on leks on a small and large study area was proportional to the number of territorial hens. Locations of leks were systematically influenced by proximity of brood habitats, and the number of cocks on leks was positively correlated with the total area of brood habitats. Establishment of a lek may depend on the prior presence of one or more territorial hens. Because hens influence establishment and size of leks, territoriality in hens may limit numbers of both cocks and hens. These findings support recent models emphasising the effects of hens on lek formation, and contrast with those from Norway, where behaviour and habitat requirements of cocks determine size and location of leks. This may result from brood habitats in the Pyrenees being in localised patches, whereas those in Norway are available throughout the forest. However, the regular distribution pattern of leks in both the Pyrenees and Norway, supports the aspect of the Norwegian model which attributes lek location to the spacing behaviour of cocks.