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
What Bird is That? kookaburra seated on and within a large red question mark. It contains 36 coloured plates of paintings of Australian birds by the author, as well as several black-and-white photographic plates of habitat. There were numerous reprints and revised editions in various formats produced well into the 1980s. The first edition was sponsored by the Gould League of Bird Lovers of New South Wales of which Cayley was a Council member. In return for its sponsorship, Cayley offered the Gould League four tenths of his 10% book royalty. However, initial sales were slow and in 1935 he sold his entire share