Gentoo Penguin(Pygoscelis papua)
The gentoo penguin is easily recognized by the wide white stripe extending like a bonnet across the top of its head and its bright orange-red bill. It has pale whitish-pink webbed feet and a fairly long tail – the most prominent tail of all penguin species. Chicks have grey backs with white fronts. As the gentoo penguin waddles along on land, its tail sticks out behind, sweeping from side to side. Gentoos reach a height of 51-90 cm, making them the third-largest species of penguin after the emperor penguin and the king penguin.
Males have a maximum weight of about 8.5 kg just before molting, and a minimum weight of about 4.9 kg just before mating. For females, the maximum weight is 8.2 kg just before molting, but their weight drops to as little as 4.5 kg when guarding the chicks in the nest. They are the fastest underwater swimmers of all penguins, reaching speeds of up to 36 km/h. Gentoos are well adapted to extremely cold and harsh climates.
Habitat
They are native to sub-antarctic islands where chilly temperatures allow for ideal breeding, foraging and nesting conditions. Despite living in cold climates, gentoo penguins typically live in ice-free areas like flat, rocky beaches and low-lying cliffs where large colonies of individuals can gather.
Diet
Gentoos live mainly on crustaceans, such as krill, with fish making up only about 15% of the diet. They are, however, opportunistic feeders, and around the Falklands are known to take roughly equal proportions of fish, squat lobsters, and squid.
Breeding
The breeding colonies are located on ice-free surfaces. Colonies can be directly on the shoreline or can be located considerably inland. They prefer shallow coastal areas and often nest between tufts of grass. In South Georgia, for example, breeding colonies are 2 km inland. In colonies farther inland, where the penguins nest in grassy areas, they shift location slightly every year because the grass will become trampled over time. Gentoos breed on many sub-Antarctic islands. The main colonies are on the Falkland Islands, South Georgia and the South Sandwich Islands, and Kerguelen Islands; smaller colonies are found on Macquarie Island, Heard Islands, Crozet Islands, South Shetland Islands, and the Antarctic Peninsula. The total breeding population is estimated to be over 600,000 birds. Gentoos breed monogamously, and infidelity is typically punished with banishment from the colony. Nests are usually made from a roughly circular pile of stones and can be quite large, 20 cm high and 25 cm in diameter. The stones are jealously guarded and their ownership can be the subject of noisy disputes and physical attacks between individuals. They are also prized by the females, even to the point that a male penguin can obtain the favours of a female by offering her a choice stone. Two eggs are laid, both weighing around 130 g. The parents share incubation, changing duty daily. The eggs hatch after 34-36 days. The chicks remain in the nests for around 30 days before joining other chicks in the colony and forming crèches. The chicks molt into subadult plumage and go out to sea at around 80-100 days.
Population
According to the IUCN Red List, they are classed as Least Concern(LC). The global population is estimated at 774,000 mature individuals. Overall, the global population is assumed to be stable. On the Falkland Islands (Malvinas), annual monitoring has provided increasing evidence of large fluctuations at the population scale over extended time periods.
Threats
Interactions with fisheries may pose a threat to the species through incidental capture in fishing nets and resource competition. The species appears to be actively feeding on discards from trawling fleets, making it susceptible to bycatch, which potentially could be causing slow but significant declines for the minority of the population whose foraging range overlaps with fisheries. Future intensification of resource competition could lead to more rapid declines for exposed populations. Increasing oil exploration around the Falkland Islands is a growing concern for the species and pollution from oil spills represents a threat on local scales. Harmful algal blooms were attributed as the cause of the paralytic shellfish poisoning incident that resulted in a major Gentoo Penguin mortality event in 2002, from which the population took several years to recover. Hence, algal blooms appear to have the potential to cause population fluctuations in parts of the global population. Recent diseases leading to massive mortality at some colonies have also been observed recently at Crozet and Kerguelen, sometime in remote colonies. The origin of such diseases is still under study. Disturbance from tourism has been shown to cause decreased breeding productivity and the associated marine traffic is likely to impact penguins foraging in inshore waters; increased understanding about the potential impacts of tourism will therefore be important. However, sites visited by tourists collectively account for less than 5% of total population in the Falklands (Malvinas), South Georgia and British Antarctic Territories.
Historically, egg collection was widespread on the Falkland Islands (Malvinas), and some legal egg collection still continues. Ingestion of plastic particles highlight the need for further assessment of the levels of microplastics in this and other penguin species in the Southern Ocean; specifically studies on temporal trends and potential effects on penguins and other organisms in the Antarctic marine food web are needed. Gentoo Penguins and the Crozet subspecies of Imperial Shag Phalacrocorax atriceps melanogenis have considerable overlap in their diets, and their congruent declines on Marion Island were likely driven by food availability linked to benthic production around the island. Hence, the species is considered to be vulnerable to environmental changes influencing local oceanography, such as frontal positions that effect food availability at the Prince Edward Islands and elsewhere. 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
Long-term monitoring programmes are in place at several breeding colonies. The origin of diseases at certain colonies (Crozet and Kerguelen) is under study.
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Conservation Actions Proposed
Continue/extend long-term monitoring of breeding colonies. Minimize disturbance to breeding colonies. The species is very much sensitive to disturbance at the Prince Edward Islands. Consider studies of approach distance, including at colonies habituated to visitors and those with no history of visitation. Minimize oil and other pollution in breeding and foraging areas as this could have significant consequences for a sedentary inshore forager like the gentoo. Terrestrial protections for Gentoo Penguins should include the protection of breeding habitat and the minimization of colony disturbance during the breeding season. In the Antarctic, visitor site guidelines already specify minimum approach distances of 5 meters and off-limit areas. Understanding and mitigating disease incidence or transfer, including in relation to climate anomalies such as El Niño, should be pursued. Investigate the eradication of invasive mice at Marion Island, as well as as investigate the impacts of non-native species at the Falkland Islands (Malvinas). Best practice guidelines for reducing risk of disease outbreaks at islands are being developed by the Agreement on the Conservation of Albatrosses and Petrels. Once available, these guidelines should be implemented. The impact of any proposed fishery on the prey of Gentoo Penguins should be carefully assessed before such a fishery is allowed. Consideration should be given to declaring marine protected areas at important feeding grounds of gentoo penguins.