Rockhopper penguin Northern Rockhopper; and the "Eudyptes chrysocome", the Southern Rockhopper. They are separated by their locations of breeding. There are four other species in the genus "Eudyptes": "E. pachyrhynchus", "E. robustus", "E. chrysolophus", and "E. schlegeli". The three subspecies of the rockhopper penguin are believed to have split up because of latitude and watermasses rather than because of geographic distances. Research suggests that during the early Pleistocene, the Southern Ocean was cold and rockhopper populations from the Atlantic and Indian Oceans remained undifferentiated and lived in the same watermass. The mid-Pleistocene climatic transition was associated with the southward migration of frontal
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