Southern rockhopper penguin eye. The rockhopper penguin complex is confusing. Many taxonomists consider all three rockhopper penguin forms subspecies. Some split the northern subspecies ("moseleyi") from the southern forms ("chrysocome" and "filholi"). Still others consider all three distinct. The subspecies recognized for the southern rockhopper penguin complex are: The northern rockhopper penguin lives in a different water mass than the western and eastern rockhopper penguin, separated by the Subtropical Front, and they are genetically different. Therefore, northern birds are sometimes separated as "E. moseleyi". The rockhopper penguins are closely related to the macaroni penguin ("E. chrysolophus") and the royal penguin ("E. schlegeli"), which
What Bird is That? according to their usual habitat. The accompanying text included brief notes on distribution, breeding and behaviour. While initial sales were poor, history tells us that Cayley had accurately discerned a market need and successfully responded to it. During WWII sales accelerated and Cayley’s first collection, reprinted time and time again, eventually became a household name among birdwatchers and the book was recognised as an Australian classic. The original sponsorship of "What Bird is That?" proved a great investment for the Gould League, who benefited from the sale of its numerous reprints and revised editions. By 1960, it was rated the