The greatest evolutionary biologist of the twentieth century? Jared Diamond, in his review of Ornithology, Evolution, and Philosphy: The Life and Science of Ernst Mayr 1904–2005 by Juergen Haffer describes one of the characteristics of Mayr as a partial answer:
Returning from an expedition to New Guinea in 1965, John Terborgh and I laid out our hundreds of bird specimens in the Harvard Museum of Comparative Zoology for Ernst Mayr to identify. Ernst had made only one collecting trip to New Guinea 36 years previously, and his last publication on New Guinea birds had appeared in 1954. Nevertheless, as he walked along the shelf and glanced at one specimen after another, he quickly identified each by its Latin species name and then by its subspecies name; he told us which zoologist had described it, in what year and in which journal; gave the alternative names under which other zoologists had discussed it; and explained its broader biological significance (for example, “Check that one for altitudinal hybridization”). He hesitated only at one obscurely mottled specimen: “See if that’s a female Rhagologus.” We found later that it was indeed a female Rhagologus, a whistler whose relatives are usually banded black and gold.
Fascinating, isn’t it? There are more such interesting information in the piece — that Mayr worked for 18 hours a day for 16 months to finish his PhD thesis; and that he published his 21st book when he was hundred years old, and seven papers after that, and so on. Though Diamond thinks that the book itself is not for public consumption, his review can certainly be read by everybody with profit. Take a look!