Northern rockhopper penguin two genera, "Austrogoniodes" and the monotypic "Nesiotinus". Within rockhopper penguins, the host-specific louse "Austrogoniodes keleri" is present only on southern rockhoppers; the multi-host "Austrogoniodes concii" parasitises only northern rockhoppers and "Austrogoniodes hamiltoni" parasitises only eastern rockhoppers. Cross contamination of the lice is not possible naturally due to the fact that chewing lice have limited mobility and heavily rely on their host for survival, meaning that the lice can only be transmitted across species by way of close physical contact. The northern rockhopper penguin feeds on krill and other sea life such as crustaceans, squid, octopus and fish. It breeds in
Free as a Bird Beatles songs, such as "Penny Lane", "Paperback Writer", "A Day in the Life", "Eleanor Rigby", "Helter Skelter", "Piggies", "The Continuing Story of Bungalow Bill", "Strawberry Fields Forever", "Doctor Robert", and "The Fool on The Hill". Between 80 and 100 allusions to the Beatles' story, music and lyrics in the video have been estimated. Although the bird can be heard at the beginning of the video, it is never seen. Neil Aspinall (Apple Records executive at the time) said that this was because no-one could agree on what kind of bird it should be. Pytka had to send his ideas to