Rare upside of climate-induced phenological changes: Gentoo penguins Pygoscelis papua aviod heat events at Martillo Isl., Tierra del Fuego, Argentina

Abstract

Heat waves have detrimental effects on most species, and particularly on cold-adapted species such as penguins. In this study we aim to understand what are the responses to heat weather events of Gentoo penguins (Pygoscelis papua) at one of their northernmost colonies: Martillo Island in Argentina. This colony was monitored using a time-lapse camera between 2013 and 2024. In this study we observe acute heat-related mortality events such as the death of five penguin chicks within forty-five minutes while registered temperatures reached 24°C. During the observation period we found Gentoos are advancing their breeding season by 2 days per year, which is concurrently reducing the number of days exposed to high temperatures (≥ 20°C). While future climate change scenarios may increase the frequency and intensity of heat waves, for now, this is a rare example in which a warming-induced phenological change withdraws chicks from potentially deadly hot summer days by fledging sooner.