The animal on the cover of Advanced Rails is a common, or Burchell's, zebra (Equus burchellii). Members of the horse family (equids), common zebras grow to a height of 45–55 inches at the shoulder and weigh 485–550 pounds. They have excellent hearing and eyesight (their night vision is comparable to that of cats or owls), and can run as fast as 35 miles per hour. Common zebras inhabit East African savannas, from treeless grasslands to open woodlands; tens of thousands of them can be found in migratory herds on the Serengeti plains. They are herbivores and feed mostly on grasses and occasionally leaves or stems. They graze for many hours each day; a zebra's teeth grow throughout its lifetime to counteract the wearing that occurs from this near-constant feeding.
Zebras are social herd animals, and the social system of the common zebra is based on a "harem" of females led by a stallion. Stallions compete for fillies that have come into their first estrus, and the filly will stay permanently with the stallion that succeeds in mating with her. Foals are dark brown and white at birth, and can walk a mere 20 minutes after birth and run within an hour. This allows them to keep up with the rest of the herd as it searches for food and water. Family groups stay together within the larger group. Communication plays a key role in the herd as well; the zebras communicate with a variety of sounds, such as barking and snorting, and with facial expressions and ear position. They even greet each other with a "smile"— a bared-teeth grimace that discourages aggression. Shared grooming further reinforces the bonds between them; they nibble at one another to remove loose hair or to help scratch those hard-to-reach spots.
Of course, the most prominent and recognizable feature of a zebra is its black and white stripes. The pattern of stripes on a zebra is as distinct as a human's fingerprints; in fact, scientists can identify individual zebras by comparing patterns, stripe widths, coloring, and scars. The stripes help serve as protection against predators in the wild such as leopards and lions; when the herd is grouped together, it is hard for the cats to discern a specific zebra to pursue. Interestingly, zebras are attracted to black and white stripes; even if the stripes are painted on a wall, a zebra will tend to migrate to them.
The cover image is from Wood's Illustrated Natural History. The cover font is Adobe ITC Garamond. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed; and the code font is LucasFont's TheSans Mono Condensed.