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<p>The decline of major known Magellanic penguin (<i>Spheniscus magellanicus</i>) colonies has highlighted the need to obtain information from other, less-studied colonies. Although smaller in size, and with only one previous assessment in the Tuckers Islets, located in Whiteside Channel in the Chilean sector of Tierra del Fuego, Chile, we updated abundance estimates and examined interannual variations in size and spatial distribution. Using a Bayesian spatial model, we analyzed three consecutive breeding seasons (2022/2023–2024/2025) on the main islet (Tucker 1), incorporating the smaller Tucker 2 during the final season. Posterior abundance estimates for Tucker 1 ranged between 1,532 (95% CI 1,039–2,185) and 1,857 (95% CI 1,521–2,370) breeding pairs, while Tucker 2 was estimated for the first time, yielding 129 (95% CI: 106–175) breeding pairs. Spatial predictions revealed shifting high-density areas (hotspot) across years in Tucker 1, and a single hotspot in Tucker 2. Although credible intervals overlapped among seasons, Tucker 1 showed an overall ~ 16.5% lower during the last season, driven by a reduction of active burrows density in the central sector, which harbors most of the breeding pairs. This lower abundance coincided with unusually high rainfall during September and October (140&#xa0;mm) compared with the two preceding seasons (24.8–28.4&#xa0;mm), likely decreasing nest-site suitability by increasing flooding risk during egg laying. Our findings highlight the need for long-term monitoring programs to track population changes and breeding success, as well as assess environmental stressors, such as extreme precipitation, which may significantly affect breeding performance under increasing climate variability.</p>

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Breeding population estimates and spatial distribution of Magellanic penguin (Spheniscus magellanicus) in the Tucker Islets, Chile

  • 期刊论文

  • 发表日期：

    2026年6月26日

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  • Jorge Acevedo,
  • Claudio A. Moraga,
  • Lisette Zenteno-Devaud,
  • Pedro Valenzuela,
  • Lautaro Oyarzún,
  • Oscar Mansilla,
  • Karen Chaura

摘要

The decline of major known Magellanic penguin (Spheniscus magellanicus) colonies has highlighted the need to obtain information from other, less-studied colonies. Although smaller in size, and with only one previous assessment in the Tuckers Islets, located in Whiteside Channel in the Chilean sector of Tierra del Fuego, Chile, we updated abundance estimates and examined interannual variations in size and spatial distribution. Using a Bayesian spatial model, we analyzed three consecutive breeding seasons (2022/2023–2024/2025) on the main islet (Tucker 1), incorporating the smaller Tucker 2 during the final season. Posterior abundance estimates for Tucker 1 ranged between 1,532 (95% CI 1,039–2,185) and 1,857 (95% CI 1,521–2,370) breeding pairs, while Tucker 2 was estimated for the first time, yielding 129 (95% CI: 106–175) breeding pairs. Spatial predictions revealed shifting high-density areas (hotspot) across years in Tucker 1, and a single hotspot in Tucker 2. Although credible intervals overlapped among seasons, Tucker 1 showed an overall ~ 16.5% lower during the last season, driven by a reduction of active burrows density in the central sector, which harbors most of the breeding pairs. This lower abundance coincided with unusually high rainfall during September and October (140 mm) compared with the two preceding seasons (24.8–28.4 mm), likely decreasing nest-site suitability by increasing flooding risk during egg laying. Our findings highlight the need for long-term monitoring programs to track population changes and breeding success, as well as assess environmental stressors, such as extreme precipitation, which may significantly affect breeding performance under increasing climate variability.