Adelie Penguin
These penguins are mid-sized, being 46-71 cm in height and 3.6-6.0 kg in weight. Distinctive marks are the white ring surrounding the eye and the feathers at the base of the bill. These long feathers hide most of the red bill. The tail is a little longer than other penguins' tails. The appearance looks somewhat like a tuxedo. They are a little smaller than most other penguin species. Adélie penguins usually swim at around 5 miles per hour. They are able to leap some 3 metres out of the water to land on rocks or ice.
Habitat
The colonies are distributed around the coastline of the Antarctic land and ocean. Colonies have declined on the Antarctic Peninsula since the early 1980s, but those declines have been more than offset by increases in East Antarctica. During the breeding season, they congregate in large breeding colonies, some over a quarter of a million pairs. Individual colonies can vary dramatically in size, and some may be particularly vulnerable to climate fluctuations. The Danger Islands have been identified as an important bird area by BirdLife International largely because it supports the colonies, with 751,527 pairs recorded in at least five distinct colonies. In March 2018, a colony of 1.5 million was discovered.
Diet
They are known to feed mainly on Antarctic krill, ice krill, Antarctic silverfish, sea krill, and glacial squid (diet varies depending on geographic location) during the chick-rearing season. The stable isotope record of fossil eggshell accumulated in colonies over the last 38,000 years reveals a sudden change from a fish-based diet to krill that began around 200 years ago. This is most likely due to the decline of the Antarctic fur seal since the late 18th century and baleen whales during the early 20th century. The reduction of competition from these predators has resulted in a surplus of krill, which the penguins now exploit as an easier source of food
Breeding
They arrive at their breeding grounds in late October or November, after completing a migration that takes them away from the Antarctic continent for the dark, cold winter months. Their nests consist of stones piled together. In December, the warmest month in Antarctica (about −2 °C or 28 °F), the parents take turns incubating the egg; one goes to feed and the other stays to warm the egg. The parent that is incubating does not eat. In March, the adults and their young return to the sea. The Adélie penguin lives on sea ice, but needs the ice-free land to breed. With a reduction in sea ice, populations of the Adélie penguin have dropped by 65% over the past 25 years in the Antarctic Peninsula. Young Adélie penguins which have no experience in social interaction may react to false cues when the penguins gather to breed. They may, for instance, attempt to mate with other males, with young chicks, or with dead females.
Population
The total global population was previously estimated at 2.37 million breeding pairs (range 1.83-2.88 million pairs) equating to 4.74 million mature individuals, based on survey data collated up to the mid-1990s. More recently, they estimated the global population to be 3.79 million pairs (range 3.52-4.10 million pairs), equating to 7.58 million mature individuals, based on satellite imagery obtained between 2006 and 2011. It was reported that the global population had increased between the times of the two global estimates in the mid-1990s and 2014, with 27% of the difference accounted for by increasing abundance at known colonies and 32% of the difference accounted for by colonies that had not previously been surveyed. Recent direct surveys in East Antarctica have estimated a greater increase in this region (average rate of increase of 1.9% per year over 30 years), indicating that the increase in the global population is probably greater than the 27%. Recent population increases were found in those regions where most of the world population breeds, including East Antarctica and Victoria Land in the Ross Sea; the species is now also increasing on the southern Antarctic Peninsula south of 66° S. In the northern Peninsula region, there is also new evidence that some populations are beginning to stabilize after decades of significant decrease; population decreases had previously occurred in the northern Peninsula region. The net change in world population is now positive. It should be noted that modelled projections in response to climate change, with associated inherent uncertainty, suggest that populations could decline north of 70áµ’S in the future, and such decline will necessitate a future re-examination of the Adélie Penguin’s status.
Threats
The current global population is exhibiting a net increase, while that portion in the northern Antarctic Peninsula is beginning to stabilize after decades of significant decrease. Computer modelling work suggests that these trends will continue in the near term but net population change may reverse in the future if climate change continues on its current track. Colonies experiencing novel conditions due to increased sea surface temperature were found to be declining or to have an unknown trend, strongly supporting ongoing environmental changes as a driver of population decline in the species. Furthermore, annual migration and winter survival may be negatively affected by decreases in sea ice coverage at northern latitudes. However, a simple latitudinal gradient in sea ice loss is unlikely, as warming so far has been regional in the Antarctic. During the summer, nesting habitat could be affected by an increase in the incidence of severe snowfall. On the basis of this and more recent modelling work, as well as continued revelations concerning climate change, it will be vital to periodically review population responses to ongoing climate variability and change.
Flightlessness and proximity to Antarctic stations and associate traffic makes the species susceptible to pollution and has previously suffered mortality from oiling, with the 1989 Bahia Paraiso oil spill near Palmer estimated to have killed 16% of local penguins. The risk of future spills remains, with potential for similar local scale impacts. The location of research stations near colonies has also led to reductions in suitable ground for breeding, excessive visits to colonies and disturbance caused by aircraft movements, although the impact of disturbance in relation to environmental conditions appears to vary with location and only impacts a small minority of sites. Human impacts potentially include disturbance from tourists, scientists, construction of new science facilities and fisheries, particularly those targeting Antarctic krill. Harvesting of krill could be a threat, if management does not adequately take into account the needs of species that feed upon krill. However, relevant (overlapping) fisheries are CCAMLR-regulated and unlikely to overlap with a majority of the population. Protection of habitat on land and at sea remains important, with the designation of appropriate protection for transit, foraging and rafting areas at sea.
Conservation
Conservation Actions Underway
This is one of the most thoroughly studied penguin species and is the subject of on-going research throughout its circumpolar range. Some colonies are located within protected areas. Human disturbance and scientific research are strictly regulated.
Conservation Actions Proposed
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. Continue international work to tackle the drivers of projected climate change.