On the spatial relationship of males on “exploded” leks: the case of Capercaillie grouse Tetrao urogallus examined by GPS satellite telemetry

Abstrakti

Themating system of Capercaillie has been referred to as “exploded lek” because displaying males are spaced farther apart than on classical leks. However, inter-male distances and spacing behavior rarely have been quantified. In 2009–2011, we examined the spatial relationships of males on two leks in southeastern Norway by GPS satellite telemetry. Largely exclusive display territories (median 2 ha) surrounded the mating site, but the males spent most of the time displaying on smaller, well-defined display sites (median 182 m2) within their territories. When on their display sites, neighboring birds were spaced 64–212 m apart; decreasing to a minimum during the time of mating. Occasionally, males made long exploratory excursions (median 243 m) across the territories of neighbors, sometimes interacting with them at close distance (<10m). During daytime, males resided solitarily in radially extending ranges within 1 km of the lek center, commuting to the lek either in the evening or morning by walking or flying, leaving in the morning mostly by walking. The distance from the lek center to night roosting trees and daytime resting areas decreased during the mating season. With interacting males and a spatial arrangement in-between that of classical leks and dispersed polygyny, the term “exploded lek” seems appropriate for the mating system of Capercaillie.