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Understanding how vital rates vary with age, life-history stage, and among populations is fundamental for predicting the demographic consequences of environmental change, especially in longer-lived species with complex life histories. These species often exhibit delayed maturity and iteroparity, making nuanced demographic insights critical for assessing their long-term viability. This study investigated age- and colony-related variation in Adélie penguin vital rates including survival, recruitment, and breeding propensity. We used mark–recapture data collected over 25 years (1996–2020) from three Adélie penguin breeding colonies that differed in population sizes and trends but comprised a metapopulation located at capes Royds, Bird, and Crozier on Ross Island, Antarctica. We used multi-state models to estimate survival and detection rates relative to reproductive state and breeding colony and estimated transition probabilities reflecting movements between reproductive states and colonies. Apparent survival varied by reproductive state, colony, and age and averaged 0.80 (SD = 0.02) at Bird, and 0.72 (SD = 0.03) and 0.73 (SD = 0.03) at Crozier and Royds, respectively, for pre-breeders age 2–7 years with strong declines in pre-breeder survival after age 8. We observed less age-related variation in survival of breeders and non-breeders, but we observed differences between colonies with lower survival for breeders (0.72 to 0.80) compared to non-breeders (0.75 to 0.82). The average probability of surviving the first 2 years after fledging ranged from 0.43 (SD = 0.14) at Royds and Crozier (0.43, SD = 0.10) to 0.55 (SD = 0.15) at Bird. Movement between colonies was highest for pre-breeders (0.00%–12.00% depending on age and colony) and lowest for breeders (<0.20%). We observed the lowest age-related recruitment rates at Royds, with recruitment at Crozier almost twice as high, and intermediate at Bird. Breeding propensity was highest at Crozier and lowest at Bird. Colony-specific variation in vital rates likely contributed differently to population trajectories, suggesting that care must be taken to extrapolate vital rate estimates across colonies even within a metapopulation. These findings also highlight the importance of considering age, life-history stage, and geographic variation when assessing population vital rates in species with complex life histories.
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This content will become publicly available on March 18, 2027
Evidence of emperor penguins’ sensitivity to sea ice fluctuations
Abstract Using satellite-derived abundance indices over 20 years, we investigated population change among the seven Ross Sea emperor penguin (Aptenodytes forsteri) colonies. We found a 90% probability that the Ross Sea metapopulation had lower springtime attendance between 2005 and 2024 (mean change = −23%; 95% CI: −46 to +20%). We identified two distinct phases of change: slightly increasing 2005 to 2019/2020, followed by a steep decline 2020–2024, resulting in a decrease of approximately 23 000 birds in 5 years or approximately 32% of the regional population. Over the 20 years, the two southernmost colonies, Cape Crozier and Cape Colbeck, increased in size, yet Beaufort, Coulman, Roget and Washington declined, resulting in a negative population trend especially evident from 2021. Asynchronous population change suggests metapopulation dynamics, with immigration from western colonies possibly driving increases at Colbeck and Crozier. Winter and spring sea ice concentration anomalies (5 year lag) and El Niño phases (1 year lag) statistically explained the most variance in our time series. Our results indicate that emperor penguins may be sensitive to sea ice fluctuations, offering insight into how this species may have adapted throughout their history and emphasizing the need for timely re-evaluation of targeted conservation strategies in an era of sea ice change.
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- Award ID(s):
- 1935870
- PAR ID:
- 10711320
- Publisher / Repository:
- The Royal Society
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 293
- Issue:
- 2067
- ISSN:
- 1471-2954
- Subject(s) / Keyword(s):
- Antarctica emperor penguin metapopulation population dynamics remote sensing sea ice concentration
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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