Northern rockhopper penguin Island in the south Atlantic Ocean. The rockhopper penguin was split into three distinct subspecies in 1992; the southern, ("E. c. chrysocome"), eastern ("E. c. filholi") and northern rockhopper penguin ("E. c. moseleyi"). The three subspecies are distinguished by differences in the length of the tassels of the crests, the size and colour of the fleshy margin of the gape, colour pattern on the underside of the flipper and differences in the size of the supercilliary stripe in front of the eye. Additionally, the northern rockhopper penguin is larger than the other two subspecies. Proof that the three subspecies were
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