Rockhopper penguin have them; these feathers develop with age. Their orange beak is initially black, but as the penguins get older, their beaks turn orange. Due to the harsh rocky environment, they cannot slide on their bellies like most penguins, so they hop to get from one place to another. What separates rockhopper penguins into subspecies is their location of reproduction and reproductive behaviors. The difference in mating signals found between the subspecies "E. chrysocome" (southern) and "E. moseleyi" (northern) seems to have occurred quickly, thus these behavioral changes are enough to isolate these taxa. Southern Rockhopper penguins are split into two
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