Northern Rockhopper Penguin

More than 99% of northern rockhoppers breed on Tristan da Cunha and Gough Island in the south Atlantic Ocean. Breeding colonies are also found on the French Southern and Antarctic Lands of Amsterdam Island and St Paul Island.

The current population is estimated to be between 100,000–499,999 breeding pairs at Gough Island, 18,000 to 27,000 pairs at Inaccessible Island, and 3,200 to 4,500 at Tristan da Cunha. In the Indian Ocean, the population was 25,500 pairs on Amsterdam Island, and 9,000 pairs on St Paul Island in 1993; there has been no information available on population trends there since the 1990s. Declines at the Atlantic Ocean sites show a decline of 2.7% per year; the 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 mice (Mus musculus) have been introduced into their environment by human sea expeditions. The mice have proven to be invasive, and consume northern rockhopper eggs, as well as hunt their young. In order to preserve the birds, a culling of the mice is being considered. The northern rockhopper penguin is classified as endangered because of the decline in numbers over the last three generations (or 30 years). Population Trends by Year and Island