Tageszeitlich früher Aktivitätsbeginn des Birkhuhns Tetrao tetrix im Aletschgebiet

On the morning of 21 May 2016, on a lek at 2200 m a.s.l. in the Aletsch region (canton of Valais), Black Grouse cocks started displaying at 3.35 h and the following day at 3.12 h CEST, 40 min earlier than the hitherto earliest observed starting time in the study area. It was a very light night with full moon and cloudless sky, and the snow cover was still nearly complete. The first calls of Rock Ptarmigan Lagopus muta were registered 79 and 88 min respectively after the first displays of Black Grouse cocks.