Rockhopper penguin positions and islands became surrounded by subtropical water masses, resulting in a split between Northern and Southern rockhopper penguins. Many advance and retreat cycles of Patagonian icecaps during the late Pleistocene may have created a barrier to gene flow between Southern Pacific and Southern Atlantic populations, causing a split between Southern and Eastern rockhopper populations. Adult Rockhopper penguins have no land-based predators. They are eaten when at sea by leopard seals, fur seals, killer whales and blue sharks. Chicks and eggs are eaten by many birds including giant petrels, skuas, sheathbills and various types of gulls. Although the rockhopper penguin
What a queer bird in Chicago", with the work allegedly first printed in the "Bulletin of the Chicago Board of Education". The "Chicago Ledger" printed the work its "Jokes and More Jokes" section in May 1922, where the word "wonderful" replaced "queer". In July 1922, it appeared as a verse of imprecise origin in the "American Consular Bulletin". When printed in the "Pleasantries" section of "The Christian Register" in September 1922, it was attributed as a "[c]omposition by foreigner in a Chicago night school." By 1980, it was published as a folk song to be sung as a round. What a queer bird "What