The animal on the cover of Mastering Blockchain is a southern rockhopper penguin (Eudyptes chrysocome), a penguin found on islands and in the surrounding waters of the subantarctic off the coasts of South America, Australia, and New Zealand. The majority of the population breeds on the Falkland Islands off of Patagonia.
These birds are among the smallest penguins, averaging 20 inches tall and weighing 6 pounds. Their most distinctive features are the yellow stripes above each small red eye that extend into eccentric yellow crests. Their blue-black waterproof coat is comprised of small feathers. Opportunistic eaters, southern rockhoppers feed on crustaceans, squid, and small fish—sometimes participating in group dives to depths of over 300 feet.
The rockhopper gets its name from the penguin’s tendency to jump over boulders and across cracks, unlike other penguins that typically navigate obstacles by sliding on their bellies or climbing using flippers. These penguins breed annually in large colonies, many returning to the same colony and even the same nest and partner, when possible.
The ICUN lists the conservation status of the southern rockhopper penguin as threatened, likely due to commercial fishing reducing available prey. Many of the animals on O’Reilly covers are endangered; all of them are important to the world.
Color illustration by Karen Montgomery, based on a black and white engraving from Meyers Kleines Lexicon. The cover fonts are Gilroy Semibold and Guardian Sans. The text font is Adobe Minion Pro; the heading font is Adobe Myriad Condensed; and the code font is Dalton Maag’s Ubuntu Mono.