Male territoriality, female range use, and spatial organisation of capercaillie Tetrao urogallus leks

Abstract

This paper compares spacing behaviour of male and female capercaillie Tetrao urogallus in the German Alps, to those reported from the boreal zone, and discusses their implications for models of lek evolution. Based on 23 males and 13 females radio-tracked during April-May 1988-1992, the size, arrangement, and overlap of home ranges of males, and home ranges, lek visitation, and location of nest sites of females are described in relation to habitat, lek location, and the birds' age. Independently of sex and age, capercaillie preferred old forest habitats. With the exception of juveniles and some subadults that used large home ranges and visited several leks, males occupied permanent but overlapping territories clumped within 1 km of lek centres. Territorial traits were most pronounced in the oldest, dominant males: they used the smallest territories closest to the lek centre, used the central parts of their territories exclusively and showed the strongest site tenacity; nevertheless they tolerated subordinates within their territories. Females stayed farther from leks than males, most visited several leks, and nested at random distances from leks. Independently of habitat, multi-lek females used larger home ranges than single-lek females. The great variation in female home range size did not agree with Bradbury's hotspot and female-preference hypotheses, indicating that female home range size may be unsuitable in revealing clues about lek evolution in capercaillie.