R Graphics Cookbook

Colophon

The animal on the cover of R Graphics Cookbook is a reindeer (Rangifer tarandus), also known as caribou in North America, which is a species of deer native to Arctic and Subarctic regions. Reindeer are ideally designed for life in hostile, cold environments, as their fur, antlers, noses, hooves, and vision have adapted to the low temperatures.

Their fur coat consists of an outer layer of straight, hollow, tubular hairs, which provide insulation from the cold and buoyancy in water, and a woolly undercoat. The coat is such an efficient insulator that when they lay on the snow, the snow does not melt. Reindeer are the only species of deer in which both male and female (and even calves) have antlers, and they have the largest antlers relative to body size among living deer species. Their antlers are shed annually and new antler growth occurs in the spring and summer.

Reindeer hooves adapt to the season: in the summer, when the tundra is soft and wet, the footpads become sponge-like and provide extra traction. In the winter, the pads shrink and tighten, exposing the rim of the hoof, which cuts into the ice and crusted snow to keep the deer from slipping. This also enables them to dig down (an activity known as cratering) through the snow to their favorite food, a lichen known as reindeer moss.

In 2012, researchers at University College London discovered reindeer are the only mammals that can see ultraviolet light. While human vision cuts off at wavelengths around 400 nm, reindeer ...