Adélie penguins north and east of the 'Adélie gap' continue to thrive in the face of dramatic declines elsewhere in the Antarctic Peninsula region

Summary

This expedition to the northern Antarctic Peninsula and Weddell Sea in 2021/22 surveyed penguin populations in a previously under-studied region. The study found that Adélie penguin populations north and east of the "Adélie gap" (a 400-kilometer stretch where no Adélies are found) have remained stable or grown over recent decades, in sharp contrast to documented population declines on the Western Antarctic Peninsula.

The research discovered new penguin colonies, revisited historical breeding sites, and found that the Adélie gap represents a true ecological boundary rather than the Peninsula mountain range itself. Gentoo penguins have also expanded their range southward into the northern Weddell Sea. Sea ice analysis showed the northeast region experienced different patterns compared to areas south of the gap, with slight increases in summer sea ice while other areas showed decreases.

Map showing Adélie and gentoo penguin breeding colonies on the Antarctic Peninsula. Lower left inset shows the Antarctic Peninsula region (highlighted in yellow) within the entire Antarctic continent. Map created using ArcGIS Pro 3.0 mapping software (https://pro.arcgis.com).

Key Findings

Researchers counted 102,142 Adélie penguin chicks across 9 breeding sites, including several previously unknown colonies.

The Devil Island population grew by 8% annually from 1996-2021, while other major colonies showed stable population trends.

The team found 3,694 gentoo penguin chicks across 4 colonies, including a new southernmost breeding colony at Cape Scrymgeour.

More than half (55%) of all Antarctic Peninsula Adélie penguins nest in the Danger Islands region.

Sea ice concentrations increased slightly during summer months northeast of the gap, while decreasing in other areas.

The "Adélie gap" represents a real ecological boundary that separates stable penguin populations from declining ones.

Abstract

While population declines among Adélie penguins and population increases among gentoo penguins on the Western Antarctic Peninsula are well established, the logistical challenges of operating in the sea ice-heavy northern tip of the Antarctic Peninsula have prohibited reliable monitoring of seabirds in this region. Here we describe the findings of an expedition to the northern and eastern sides of the Antarctic Peninsula—a region at the nexus of two proposed Marine Protected Areas—to investigate the distribution and abundance of penguins in this region. We discovered several previously undocumented penguin colonies, completed direct surveys of three colonies initially discovered in satellite imagery, and re-surveyed several colonies last surveyed more than a decade ago. Whereas our expectation had been that the Peninsula itself would divide the areas undergoing ecological transition and the apparently more stable Weddell Sea region, our findings suggest that the actual transition zone lies in the so-called "Adélie gap," a 400-km stretch of coastline in which Adélies are notably absent. Our findings suggest that the region north and east of this gap represents a distinct ecoregion whose dynamics stand in sharp contrast to surrounding areas and is likely to be impacted by future conservation measures.

Published in

Scientific Reports

2023

Authors

Wethington, M., Flynn, C., Borowicz, A., Lynch, H. J.

Institutions

Department of Ecology and Evolution, Stony Brook UniversitySchool of Marine and Atmospheric Sciences, Stony Brook UniversityInstitute for Advanced Computational Science, Stony Brook University

Methods

Biological sampling DataField

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