Deer: The Animal Answer Guide

3. Deer Coat Colors

36 What are the functions of the coat in deer? The coat (or pelage) of a deer serves a variety of functions, including acting as a barrier to biting insects and protecting against the harmful effects of solar radiation. Primarily, however, the function of the pelage is insulation. Insulation is critical for all but tropical deer species during the winter, especially for those at higher latitudes, such as caribou (Rangifer tarandus), red deer (Cervus elaphus), moose (Alces alces), and southern huemul (Hippocamelus bisulcus); or those at high elevations, such as southern pudu (Pudu puda) and white-lipped deer (Przewalskium albirostris). The long, coarse outer coat of guard hairs and the thick, wooly underfur of these species allow them to endure very cold temperatures. For example, white-lipped deer can withstand the freezing conditions that occur at elevations of 16,200 feet (5,400 m) or more in the mountains of Tibet, where they experience very few frost-free days annually. The length and density of the hairs and the insulating capacity of the coat vary seasonally in most species (see “Seasonal Differences”). A deer’s coat also functions as camouflage . The concealing (cryptic) color and spotting patterns that occur in most young deer help them hide from predators. Anyone who has ever searched for newborn fawns knows how effective this coat pattern is—they are exceptionally difficult to locate visually. Third, pelage can communicate warnings among deer in a group and alert them to potential danger. This is certainly the case with the wellknown tail flagging behavior of white-tailed deer (Odocoileus virginianus) when they are alarmed and flee (see chapter 4)—a behavior also seen in South American marsh deer (Blastocerus dichotomus) and pampas deer (OzoChapter 3 Deer Coat Colors 37 Deer Coat Colors toceros bezoarticus). The white or cream-colored rump patches of several species, including red deer and elk (Cervus elaphus), sika deer (C. nippon), and roe deer (genus Capreolus), serve the same function. When an individual becomes alarmed or senses danger, it flares its rump patch as a warning signal to others in the herd. This flaring of hairs on the rump, a movement that looks like a flower petal suddenly opening, results from the contraction of the small muscles at the base of each hair (the erector pili) in the dermis (the layer of tissue beneath the outer layer of skin). A flagging tail or flaring rump patch is absent in smaller, solitary deer species that inhabit dense vegetation. Finally, the coat provides buoyancy when deer swim, because the center of each hair shaft is hollow and filled with air. Many species— Chinese water deer (Hydropotes inermis), caribou, marsh deer, and others— are closely associated with water, and all deer are good swimmers. Left, Unlike red deer, caribou have a pronounced white neck mane. Right, Their thick winter pelage (coat), including the heavy neck mane, allows red deer to make it through the winter. Photos courtesy of Karen Laubenstein, U.S. Fish and Wildlife Service (USFWS) (left) and by Rory Putman (right). The cryptic (camouflaged) spotting pattern of white-tailed deer fawns can make them difficult to see in heavy underbrush. Photo from ForestWander Nature Photography. 38 Deer: The Animal Answer Guide The structure of hair (or fur—the terms are synonymous) is the same in deer as it is in most other mammals. A typical hair has three well-defined layers. The center, or core, of a hair shaft is called the medulla. It has a variety of different structural patterns in different species, but it is usually hollow in deer. The cortex makes up most of the hair shaft, and it is formed from tightly packed cells that surround the medulla. Finally, a transparent, thin, scalelike outer layer makes up the cuticle of each hair. Deer have three types of hair. Guard hairs form an outer layer of long, coarse body hairs. The guard hairs of deer are called awns; they have a weak base and a heavier tip, so they lay down in one direction. Guard hairs overlay the shorter, finer, more closely spaced underfur that makes up most of the pelage of deer. In addition, like other mammals, deer have long, stiff, specialized hairs (vibrissae) around the snout (the whiskers) and eyes (the eyelashes). These hairs are connected to nerves and serve a tactile function —that is, they convey a sense of touch. What causes the different coat colors...