Fifty-year change in penguin abundance on Elephant Island, South Shetland Islands, Antarctica: results of the 2019–20 census

Elephant Island sits on the front lines of ecological change in the Scotia Arc region, but most of the island has remained unsurveyed for nearly 50 years. As a result, there has been no way to establish whether changes on the island reflect those to the south along the Western Antarctic Peninsula or whether, in contrast, populations have remained stable, as on the more northerly South Sandwich Islands. At the core of the Chinstrap Penguin (Pygoscelis antarcticus) breeding range, at the southern edge of the Macaroni Penguin (Eudyptes chrysolophus) and (very recently) King Penguin (Aptenodytes patagonicus) ranges, at the northern limit of the Adélie Penguin (Pygoscelis adeliae) range, and in an area where Gentoo Penguin (Pygoscelis papua) populations are expanding southward, Elephant Island is situated at a unique ecological crossroads, hosting both sub-Antarctic and Antarctic seabirds, the former of which may be responding favorably to the very same climate changes that imperil the latter. Fortunately, an exhaustive census of the island in 1970–71 provides a rigorous baseline against which to document ecological change. Here, we report on the first complete survey of the island since 1970–71, conducted from January 9–20, 2020. Results indicate a decrease in Chinstrap Penguin populations, a doubling of Gentoo Penguins, a stable number of Macaroni Penguins, continuing occupancy by a few Adélie Penguins, and evidence of King Penguin breeding expansion. Our findings demonstrate that Elephant Island’s seabird community has changed dramatically over the past five decades and that these changes appear to be ongoing.