species such as the chital, the fallow deer and the sika deer feature white spots on a brown coat. Coat of reindeer shows notable geographical variation. Deer undergo two moults in a year; for instance, in red deer the red, thin-haired summer coat is gradually replaced by the dense, greyish brown winter coat in autumn, which in turn gives way to the summer coat in the following spring. Moulting is affected by the photoperiod. Deer are also excellent jumpers and swimmers. Deer are ruminants, or cud-chewers, and have a four-chambered stomach. Some deer, such as those on the island of Rùm, do consume meat when it is available. Nearly all deer have a facial gland in front of each eye. The gland contains a strongly scented pheromone, used to mark its home range. Bucks of a wide range of species open these glands wide when angry or excited. All deer have a liver without a gallbladder. Deer also have a tapetum lucidum, which gives them sufficiently good night vision. Antlers All male deer possess antlers, with the exception of the water deer, in which males have long tusk-like canines that reach below the lower jaw. Females generally lack antlers, though female reindeer bear antlers smaller and less branched than those of the males. Occasionally females in other species may develop antlers, especially in telemetacarpal deer such as European roe deer, red deer, white-tailed deer and mule deer and less often in plesiometacarpal deer. A study of antlered female white-tailed deer noted that antlers tend to be small and malformed, and are shed frequently around the time of parturition. The fallow deer and the various subspecies of the reindeer have the largest as well as the heaviest antlers, both in absolute terms as well as in proportion to body mass (an average of eight grams per kilogram of body mass); the tufted deer, on the other hand, has the smallest antlers of all deer, while the pudú has the lightest antlers with respect to body mass (0.6 g per kilogram of body mass). The structure of antlers show considerable variation; while fallow deer and elk antlers are palmate (with a broad central portion), white-tailed deer antlers include a series of tines sprouting upward from a forward-curving main beam, and those of the pudú are mere spikes. Antler development begins from the pedicel, a bony structure that appears on the top of