Late Holocene occupation of Gentoo Penguins (Pygoscelis papua) on Byers Peninsula, Livingston Island, Antarctica

Abstract

We report excavations of an abandoned penguin colony on Byers Peninsula, Livingston Island, Antarctica, in austral summer 2008/2009. Nine abandoned pebble mounds were located on Devils Point, near an active Gentoo Penguin (Pygoscelis papua) colony of about 3,000 nests, at an elevation of 40–45 m above sea level. Three of the nine mounds were excavated to recover organic remains for radiocarbon and ancient DNA analyses; two additional mounds were probed to obtain tissue samples for additional dating. All radiocarbon dates were corrected for the marine-carbon reservoir effect using a ΔR of 700 ± 50 years. Calibrated 2-sigma ranges in calendar years before present (B.P.) on 23 samples of egg membrane and bone provided an overall range of 40–1,150 B.P., with most of the dates falling between 225 and 465 B.P. Ancient DNA analysis confirmed that the tissues recovered from these excavations represent Gentoo Penguin. One radiocarbon date from the active Gentoo Penguin colony indicated an age of 285–480 B.P. for the initiation of this current occupation and corresponding in age with most of the abandoned mounds. Although geologic evidence indicates that Byers Peninsula has been ice free for at least 3,000 years, these results indicate that penguin occupation lagged behind deglaciation by over 2,000 years. Small numbers of Chinstrap Penguins (P. antarctica) also occupy the same breeding colonies as Gentoo Penguins at Byers Peninsula, but their absence in the ancient sediments suggests that they have only recently colonized this area.