FIGURE 1. Inspiratory calling of Bombina bombina (above) and expiratory calling in Pelophylax kl. esculentus (below). Oscillograms show one call and small photos show state of vocal sac at the respective time indicated. Video and sound recorded with a Nikon D750 and processed in Windows Movie Maker software; oscillograms drawn in CoolEdit Pro 2.0 software. Recording of Bombina made at Schorfheide-Chorin Reserve, Germany on 24 May 2015; recording of Pelophylax made at Riddagshausen Reserve, Braunschweig, Germany, on 2 June 2015.