Lek site defines annual spatial use of male Black Grouse (Tetrao tetrix)

Abstract

Adult male Black Grouse ( Tetrao tetrix ) are assumed to use the same lek throughout their life-span and juveniles are rarely observed settling far from their natal areas. Here we re- port results on a study of lek site fidelity in male Black Grouse using mark-recapture, ra- dio-telemetry, and lek observations between 1984 and 1992. Data were collected at two sites in central Sweden with six and two lek s, respectively. A total of 306 Black Grouse (230 full-grown adult and juvenile males, and 76 chicks) were captured and tagged. We found that all recaptured males tagged as chicks ( n = 7) were caught on the lek closest to their initial capture site. Twenty-six percent ( n = 59) of individuals ringed as full-grown were recaptured at least once in the subseque nt springs. Fewer individuals attended leks during the mating period than the premating period ( t (15) = 3.06, P = 0.008). Juvenile males were closer to the lek in the premating period (95% confidence interval = 0.45–0.65 km) than in the mating period (0.73–1.13 km), in contrast to adults, which were closer to leks in the mating period (0.44–0.61 km) than the premating period (0.80–0.95 km). Inter-lek movement probability of the birds was 15% ( n = 9) in the study area. Male Black Grouse remain close to their lek all year round and their recruitment is local. This indicates that leks consist of well-defined local populations , which have limited interactions with other leks.