Effect of Environmental Variables on African Penguin Vocal Activity: Implications for Acoustic Censusing oleh Franziska Hacker, Francesca Terranova, Gavin Sean Petersen, Emma Tourtigues, Olivier Friard, Marco Gamba, Katrin Ludynia, Tess Gridley, Lorien Pichegru, Nicolas Mathevon, David Reby, Livio Favaro