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Adelie Penguin Pygoscelis adeliae

This species has been uplisted to Near Threatened because it is expected to undergo a moderately rapid population decline over the next three generations owing to the effects of projected climate change. It should be noted, however, that there are considerable uncertainties over future climatic changes and how they will impact the species.

Taxonomic source(s)
Christidis, L.; Boles, W. E. 2008. Systematics and taxonomy of Australian birds. CSIRO Publishing, Collingwood, Australia.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
SACC. 2006. A classification of the bird species of South America. Available at: #
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Distribution and population
Pygoscelis adeliae is found along the entire Antarctic coast and some of its nearby islands. Individuals are dispersive, moving towards areas of persistent sea ice to moult after breeding (Ainley et al. 2010). Numbers are increasing in the Ross Sea region and decreasing in the Peninsula region, with the net global population increasing overall (Ainley et al. 2010). However, analyses based on the modelling of climate effects suggest that the population could start to decline in a few decades (Ainley et al. 2010, D. Ainley in litt. 2012). Although these declines may only start after a warming of 2°C above pre-industrial levels is reached, and overall trends will potentially be positive before this point (D. Ainley in litt. 2012), BirdLife International has precautionarily projected a population decline approaching 30% over the next three generations, factoring in the potential for negative impacts to take place within this timescale, as well as substantial uncertainties over climate predictions and the adaptability of the species. 

Population justification
The total number of breeding pairs is estimated at c.2.37 million (range 1.83-2.88 million), based on survey data collated and published by Woehler (1993) and Woehler and Croxall (1997), equating to at least 4.74 million mature individuals.

Trend justification
An analysis carried out by Ainley et al. (2010) suggests that all colonies north of 67-68°S could be lost by the time that Earth's average tropospheric temperature reaches 2°C above pre-industrial levels, with negative impacts on all colonies north of 70°S. In this study, 2042 is the median year (range 2025-2052) at which a 2°C warming is forecast to be exceeded by the four climate models used (those models used in the IPCC Fourth Assessment Report [AR4] that most closely predicted data collected on environmental conditions in the Southern Ocean over recent decades) (Ainley et al. 2010). An ensemble of these models was then used to predict changes in climate and habitat in the Southern Ocean until 2025- 2052, namely sea ice extent, persistence, concentration and thickness, wind speeds, precipitation and air temperature. Predictions were then made based on historic responses of the species to past variation in environmental conditions (Ainley et al. 2010). Although the declines predicted by Ainley et al. (2010) may only start after a warming of 2°C above pre-industrial levels is reached, and overall trends will potentially be positive before this point (D. Ainley in litt. 2012), BirdLife International has carried out a population trend projection over three generations (36 years; trend period 2012- 2048), assuming an exponential decline, based on the precautionary assumption that negative impacts will occur before a warming of 2°C is reached. The current total number of breeding pairs is estimated at 2.37 million (range 1.83-2.88 million), based on survey data collated and published by Woehler (1993) and Woehler and Croxall (1997). According to the same data, the number of pairs situated in colonies north of 67°S is estimated to be 926,000 (range 595,000-1,270,000). A trend projection is made based on the loss of colonies north of 67°S over a time scale of 2012-2042, projecting a decline of c.45% over 36 years (by 2048). However, in this species some relocation of colonies is expected, with growth perhaps occurring south of 73°S (Ainley et al. 2010). The species would be expected to colonise new areas as the collapse of ice shelves in northern portions of its range exposes new areas of coastline, and as highly concentrated sea ice at southern latitudes becomes more divergent. Reduced suitability of nesting habitat, however, could result from an increase in the incidence of severe snowfall. In addition, annual migration and winter survival may be negatively affected by decreases in sea ice coverage at northern latitudes where the species requires a few hours of daylight in each 24-hour period (Ainley et al. 2010, Ballard et al. 2010). It has been shown, however, that a simple latitudinal gradient in the loss of sea ice is unlikely, and that warming has so far been regional in the Antarctic (Zwally et al. 2002, Turner et al. 2009, Trathan et al. 2011, Fretwell et al. 2012). With these uncertainties in mind, the species is projected to decline at a rate of 20-29% over the next three generations.

This species nests on ice-free rocky coasts, often in extensive open areas to accommodate typically large colonies which may be far from the open sea. Females lay two eggs, which are incubated by both sexes in alternating stints. It mainly feeds on krill, with smaller quantities of fish, amphipods and cephalopods. It captures such prey by pursuit diving, usually less than 20 m down (del Hoyo et al. 1992).

It is thought to be threatened by the effects of projected climate change, primarily through future decreases in sea ice concentration, as affected by wind speed and persistence, as well as associated changes in other climatic variables such as precipitation (Ainley et al. 2010). Reduced suitability of nesting habitat could result from an increase in the incidence of severe snowfall. In addition, annual migration and winter survival may be negatively affected by decreases in sea ice coverage at northern latitudes where the species requires a few hours of daylight in each 24-hour period (Ainley et al. 2010, Ballard et al. 2010). The location of research stations near colonies has led to reductions in suitable ground for breeding, excessive visits to colonies and disturbance caused by aircraft movements (del Hoyo et al. 1992), although the impact of disturbance in relation to environmental conditions appears to vary with location (Bricher et al. 2008). Oil-pollution and fishing (for krill and finfish) also pose threats (D. Ainley in litt. 2012).

Conservation Actions Underway
This is the most studied penguin species (del Hoyo et al. 1992), and is the subject of on-going research. Some colonies are located within protected areas. Human disturbance is strictly regulated.

Conservation Actions Proposed
Carry out surveys to obtain an improved and more up-to-date population estimate. Continue to monitor population trends. Continue to closely monitor trends in the extent and persistence of sea ice, and associated climatic variables. Carry out further research into the species's ecology to improve understanding of how environmental changes and human activities, such as fishing, will affect the population. Improve predictions of future environmental changes and how these will impact the species's population, and conduct research into the potential effects of fish and krill extraction (D. Ainley in litt. 2012). Continue international work to tackle the drivers of projected climate change.

Ainley, D.; Russell, J.; Jenouvrier, S.; Woehler, E.; Lyver, P. O’B.; Fraser, W. R.; Kooyman, G. L. 2010. Antarctic penguin response to habitat change as Earth’s troposphere reaches 2°C above preindustrial levels. Ecological Monographs 80: 49-66.

Ballard G.; Toniolo, V.; Ainley, D. G.; Parkinson, C. L.; Arrigo, K. R.; Trathan, P. N. 2010. Responding to climate change: Adélie penguins confront astronomical and ocean boundaries. Ecology 91: 2056-2069.

Barbraud, C.; Weimerskirch, H. 2006. Antarctic birds breed later in response to climate change. Proceedings of the National Academy of Sciences of the United States of America 103(16): 6248-6251.

Bricher, P. K.; Lucieer, A.; Woehler, E. J. 2008. Population trends of Adélie penguin (Pygoscelis adeliae) breeding colonies: a spatial analysis of the effects of snow accumulation and human activities. Polar Biology 31: 1397-1407.

del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Forcada, J.; Trathan, P. N.; Reid, K.; Murphy, E. J.; Croxall, J. P. 2006. Contrasting population changes in sympatric penguin species in association with climate warming. Global Change Biology 12: 411-423.

Fretwell, P. T.; LaRue, M. A.; Morin, P.; Kooyman, G. L.; Wienecke, B.; Ratcliffe, N.; Fox, A. J.; Fleming, A. H.; Porter, C.; Trathan, P. N. 2012. An Emperor Penguin Population Estimate: The First Global, Synoptic Survey of a Species from Space. PLoS ONE 7(4).

Hinke, J. T.; Salwicka, K.; Trivelpiece, S. G.; Watters, G. M.; Trivelpiece, W. Z. 2007. Divergent responses of Pygoscelis penguins reveal a common environmental drive. Oecologia 153: 845-855.

Trathan P. N.; Fretwell P. T.; Stonehouse, B. 2011. First Recorded Loss of an Emperor Penguin Colony in the Recent Period of Antarctic Regional Warming: Implications for Other Colonies. PLoS ONE 6(2).

Turner, J.; Comiso, J. C.; Marshall, G. J.; Lachlan-Cope, T. A.; Bracegirdle, T.; Maksym, T.; Meredith, M. P.; Zhaomin Wang; Orr, A. 2009. Non-annular atmospheric circulation change induced by stratospheric ozone depletion and its role in the recent increase of Antarctic sea ice extent. Geophysical Research Letters 36.

Weimerskirch, H.; Inchausti, P.; Guinet, C.; Barbraud, C. 2003. Trends in bird and seal populations as indicators of a system shift in the Southern Ocean. Antarctic Science 15: 249-256.

Woehler, E. J. 1993. The distribution and abundance of Antarctic and Subantarctic penguins. Scientific Commission on Antarctic Research, Cambridge, U.K.

Woehler, E. J.; Cooper, J.; Croxall, J. P.; Fraser, W. R.; Kooyman, G. L.; Miller, G. D.; Nel, D. C.; Patterson, D. L.; Peter, H.-U.; Ribic, S. A.; Salwicka, K.; Trivelpiece, W. Z.; Weimerskirch, H. 2001. A statistical assessment of the status and trends of antarctic and subantarctic seabirds.

Woehler, E. J.; Croxall, J. P. 1997. The status and trends of antarctic and sub-antarctic seabirds. Marine Ornithology 25: 43-65.

Zwally, H. J.; Comiso, J..C; Parkinson, C. L.; Cavalieri, D. J.; Gloersen, P. 2002. Variability of Antarctic sea ice 1979–1998. Journal of Geophysical Research 107.

Further web sources of information
Explore HBW Alive for further information on this species

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Text account compilers
Butchart, S., Calvert, R., Ekstrom, J., Taylor, J.

Ainley, D., Kooyman, G., Woehler, E.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Pygoscelis adeliae. Downloaded from on 01/08/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 01/08/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Adélie penguin (Pygoscelis adeliae) 0

Key facts
Current IUCN Red List category Near Threatened
Family Spheniscidae (Penguins)
Species name author (Hombron & Jacquinot, 1841)
Population size 4740000 mature individuals
Population trend Increasing
Distribution size (breeding/resident) 148,000 km2
Country endemic? No
Links to further information
- Additional Information on this species