原版书书名：MongoDB Applied Design Patterns
The animal on the cover of MongoDB Applied Design Patterns is the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), also known as the leopard ground squirrel, squinney, or striped gopher. It gains both its Latin name (tredecim meaning thirteen) and common name from the 13 alternating dark and light lines that run down its back and sides. It also has spots within the darker stripes of fur, which help camouflage the animal in its grassland habitat.
Thirteen-lined ground squirrels are widespread in the Great Plains region of North America, and in fact are the reason for Minnesota’s nickname “The Gopher State” (though this is a misnomer, as they are not members of the gopher family). Strictly active during the day, this squirrel’s diet consists of grass, seeds, and insects. They prefer open areas with short grass and well-drained soil for creating their burrows. Though they live individually rather than in colonies, there may be as many as 20 ground squirrels per acre in a particularly good habitat.
These animals range from 6–11 inches long, and their weight varies widely depending on the time of year. Most usually weigh between 5–6 ounces, but can get near half a pound when preparing for winter hibernation. In preparation, the ground squirrel puts on a heavy layer of fat and stores food in its burrow. Around October, it enters the burrow, rolls into a tight ball, and decreases its respiration to about one breath every five minutes, until it emerges again in March or April.
Each thirteen-lined ground squirrel’s burrow is around 15–20 feet long, with several side passages and multiple entrances. With the exception of the hibernation chamber, the burrows are no more than 1-2 feet below the surface. Typically, the tunnel turns sharply near its beginning, to trick digging predators into believing that the burrow has dead-ended.