Southern rockhopper penguin first noted. Their breeding colonies are located from sea-level to cliff-tops and sometimes inland. Their breeding season starts in September and ends in November. Two eggs are laid but only one is usually incubated. Incubation lasts 35 days and their chicks are brooded for 26 days. Foraging behavior in penguins varies across ecological conditions. Rockhopper penguins are present at a variety of climates and locations; Amsterdam Island's (AMS) subtropical waters, Kerguelen Archipelago's (KER) subarctic coastal waters, and Crozet Archipelago's (CRO) subantarctic coastal waters. Due to the species plasticity they are able to express different strategies and foraging behaviors depending on
Northern rockhopper penguin drop in the population at Gough Island has been described as equivalent to the loss of 100 birds every day since the 1950s. A study published in 2009 showed that the world population of the northern rockhopper had declined by 90% since the 1950s, possibly because of climate change, changes in marine ecosystems and overfishing for squid and octopus by humans. Other possible factors in the decline include disturbance and pollution from ecotourism and fishing, egg-harvesting, and predation and competition from subantarctic fur seals ("Arctocephalus tropicalis"). Surveys show that the birds are at risk of infection by goose barnacles. House