The breeding areas of the South American penguins are mainly on the western coast and range from Peru over Tierra del Fuego to the Falkland Islands. In all, six penguin species are distributed in South America. Macaroni, Southern Rockhopper and Magellanic Penguins are living in Argentina, Chile and on the Falkland Islands which are located north-easterly from the southern tip of South America. On the Falkland Islands you can also find King and Gentoo Penguins. Humboldt Penguins are living in Peru and Chile only.
The climate in South America is influenced by the Andes, the Atacama Desert and the cold Humboldt current. A large part of the distribution area of the penguins is located in a cold temperate climate zone. The average temperature in summer is 11°C and 1°C in winter (for Torres del Paine National Park in Chile). The temperature fluctuations in the different seasons are also low.
On the Falkland Island it is often very windy and rainy. The wheather is characterized by quick changes. It is not surprising to experience typical wheather conditions of all four seasons in one evening.
The distribution area of Magellanic Penguins is predominated by grassland, the so-called pampas. Hollows in the ground or bushes serve as nests. Some individuals lay their eggs on the ground and protect it with all sorts of soft material they can find. Macaroni and Southern Rockhopper Penguins, however, nest at steep coasts in crevices.
Humboldt Penguins use burrows in the ground or crevices as nesting sites. Gentoo Penguins either nest between hassocks or they build their nests out of little stones which are hard-fought, especially in the breeding season.
In contrast to the mentioned penguin species, King Penguins do not build nests. They carry their single egg on their feet and warm it with their abdominal brood pouch. After hatching, the chick is also carried on the feet of its parents for a while.
Some of the South American penguin species are classified as "vulnerable" by the IUCN. Above all, the populations of Magellanic, Humboldt and Southern Rockhopper Penguins are minimized by external influences. Due to climate change and increased fishing the food of the penguins either migrate or diappear, so the penguins have to cover longer distances or starve. Besides, accidents of oil-tankers are a common cause of death of many penguins.
Because of guano mining by humans a very suitable material for nest building is removed. Humans use guano as fertilizer, but Humboldt Penguins need guano to protect their clutch and chicks. Guano is dried excrement of penguins and other seabirds. It is a soft material and penguins can dig burrows in the guano covered ground easily. But if guano is mined, hard ground will be left and Humboldt Penguins cannot build nests. That is why the survival rate of chicks is reduced.
Another reason for the decline of the population of Humboldt Penguins is egg collecting. That activity is also common on the Falkland Islands. Today it is forbidden by law to collect the eggs of Southern Rockhopper Penguins. But it is still allowed to take the eggs of Gentoo Penguins under supervision by the government.
Although the population size of Macaroni Penguins is with 9 million breeding pairs worldwide the highest of all penguin species, they are classified as "vulnerable" by the IUCN. The reason is that the population has declined by 30% in the last ten years and increasing human influence like fisheries activities.
Fortunately, the King Penguin is one of the least penguin species that is listed as "least concern" by the IUCN. Their population size is large and predicted as increasing. Nevertheless, the fisheries industry is still a strong food competitor for the penguins.
Book: Penguins - Natural History an Conservation, edited by P.G. Borboroglu and P.D. Boersma
Wikipedia articles: King Penguin, Gentoo Penguin, Magellanic Penguin, Southern Rockhopper Penguin, Falkland Islands, Torres del Paine National Park (in English and German)