Spacing of Adult and Subadult Male Common Capercaillie during the Breeding Season

Abstract

The spacing behavior of 58 male Common Capercaillie (Tetrao urogallus) was studied at Varaldskogen in southeast Norway during 1979-1985. Birds captured at leks were equipped with radio-transmitters, and their movements were monitored throughout the year. During spring, males 4 yr old and older occupied exclusive day territories of 10.2-66.0 ha that extended radially from a center at the lek. Adult cocks used the same lek and the same territory during successive years. Among marked birds, the youngest bred at 4 yr. No difference was found in territory size between breeding and nonbreeding adult males. Territories of 3-yr-olds (60.8 ± 10.4 ha) were larger than those of older males (26.3 ± 5.0 ha) and were located farther from the lek. All territories were within a 1.2-km radius of the lek center and were maintained from early April to the end of May. Yearlings and 2-yr-old males were nonterritorial. They moved irregularly among different, neighboring leks, settling near one lek at the end of their second spring season. When associated with one lek, their home ranges were 3-6 times larger than and overlapped peripherally the territories of resident adults. Established subadult and adult males did not change territories when vacancies were created by deaths of older birds, and successful matings were not dependent on occupying a particular territory.