The animals on the cover of Mastering Regular Expressions, Second Edition, are
owls. There are two families and approximately 180 species of these birds of prey distributed throughout the world, with the exception of Antarctica. Most species of owls are nocturnal hunters, feeding entirely on live animals, ranging in size from insects to hares.
Because they have little ability to move their large, forward-facing eyes, owls must move their entire heads in order to look around. They can rotate their heads up to 270 degrees, and some can turn their heads completely upside down. Among the physical adaptations that enhance owls