Buck rubs and buck scrapes are two types of markings made by white-tailed deer. A. The observation that deer sniff and lick buck rubs first led scientists to connect buck rubs with combat between adult males during the breeding season. B. Buck rubs and buck scrapes are visual signals and smells that deer use to communicate a variety of information to other deer. C. The number of buck rubs and buck scrapes in a given area changes as the density of the population of male deer in the area changes. D. As they rub the bark from trees, male deer leave behind chemicals produced by the glands in their foreheads, creating a scent that other deer can detect. E. The height of a buck rub, the type of tree used, and the direction in which the deer applies the rub can give different kinds of information to other deer. F. Buck rubs are created close to the breeding season of deer and may affect the timing of fertility in the female deer that visit the rubs.