Southern rockhopper penguin may just be a colour morph of the macaroni penguin. Interbreeding with the macaroni penguin has been reported at Heard and Marion Islands, with three hybrids recorded there by a 1987-88 Australian National Antarctic Research Expedition. The southern rockhopper penguin group has a global population of roughly 1 million pairs. About two-thirds of the global population belongs to "E. c. chrysocome" which breeds on the Falkland Islands and on islands off Argentina and southern Chile. These include most significantly Isla de los Estados, the Ildefonso Islands, the Diego Ramírez Islands and Isla Noir. "E. c. filholi" breeds on the Prince
What Bird is That? all-time best seller in Australian natural history and is still in print today. While sales and stature of Cayley’s original collection continued to grow, the prolific artist and ornothologist Cayley was working on a much more ambitious project – his so-called “big bird book”. From about 1918, he was creating illustrations of subspecies, plumage stages and eggs (now lost) of all known Australian birds. The project was incomplete at the time of his death in 1950, although the illustrations were all but finished. The ornithologist Terence Lindsey revived Cayley’s plans in the 1980s, creating the last and most significant revision