This is a great photo of a dominant breeding buck in his prime. Unfortunately, this buck was killed by a poacher. Note his arched tail, his enlarged neck, and the wrinkles on his neck. That wrinkling is caused by fluid from scalp musk. Note the enlarged tarsal gland on the inside of his left rear leg — with its tuft of white hair.
Following a summer of little activity ending with velvet shedding about September 1st, Phase I of the whitetail rut begins. This is the first period during which antlered bucks begin preparing for breeding, still more than two months away. First on the list of whitetail bucks 2-1/2 year of age or older is exploring the entire extent of their home ranges. This important step improves their odds for survival during their most dangerous seasons of the year, the season of being hunted by great numbers of humans, and in Minnesota, the much longer season of being hunted by packs of grey wolves, newly formed in early November. While exploring, bucks also become acquainted or reacquainted with all other deer living within their ranges, many of which will play prominent roles in their lives durng the coming 4-1/2 months.
Next on the list of all antlered bucks, including yearlings, is battling with other bucks to achieve the highest position possible in their hierarchy of bucks living in the square mile home range of the previous year’s dominant breeding buck. This goes on for about a month and a half (until Mid-October). The overall victor finally wins a year of mastery over all other deer living within this square mile plus the exclusive opportunity to breed all mature and yearling does living there — the genetically driven goal of every white-tailed buck. Only about 10% succeed, however.
Within a few days after velvet shedding, all antlered bucks living in their shared square mile begin to graze in one feeding area twice daily. Late during feeding hours, whether accidental or deliberate, bucks often feed so near one another that their antlers touch — an action regarded by all bucks as a provocation to battle.
Battles between whitetail bucks are actually shoving matches. With heads lowered, antlers engaged, they push with considerable might toward one another until one is driven several yards back and must leap way to avoid injury. After one or more of such engagements, the victor is accepted by the loser as being dominant throughout the following year. The loser is obliged to move quickly aside when approached by the victor, back away when threatened, flee when pursued and even allow the victor to take possession of the food it is feeding on or the wintering area bed it is lying on. Failure to comply earns a swift kick to the ribs. Thus is created the pecking order of all bucks living within a square mile. One buck ends up at the bottom of the pecking order, then subservient to all other bucks, and one ends up at the top of the pecking order, then domineering over all other bucks (none of which will have the opportunity to breed, except, perhaps, in their wintering area following the third week in December). The dominant breeding buck and most other non-breeding bucks 3-1/2 years of age or older are dominant over all does (except those in heat) and their young. While in the presence of any of these other deer, a dominant breeding buck will typically display its badge of royalty: an arched tail held slightly away from its rump.
Initially during this phase, bucks very briefly spar with one another, antlers clicking a few times, showing little enthusiasm. By the end of September and throughout the first half of October when testosterone is beginning to peak, battles become fierce and extended, tempers flaring. Yearling bucks, always anxious to provoke battles with other bucks including those highest in the pecking order are quickly defeated, but that doesn’t seem to discourage them. Battles between older, more evenly matched bucks, are usually prolonged, occasionally repeated, and sometimes bloody.
During this rut phase certain physical changes occur in antlered bucks. Muscles of their necks enlarge to varying degrees, especially noticeable on dominant breeding bucks 4-1/2 to 6-1/2 years of age (few live longer). Some (not all) younger bucks including yearlings develop unusually enlarged necks as well. Bucks with enlarged necks likely have an advantage over other bucks, enabling them to overpower and painfully turn or twist the necks of less muscular opponents while driving them backwards, soon forcing them to give up the battle.
Note how the buck has his rear knees close together and his tail is arched. He is urinating on his rear tarsal glands while rubbing them together. When bucks wag their rear ends back and forth while doing this it resembles a hula dance. In the process, this dance carries the scent from his tarsal glands to the ground scrape he is working on.
Enlarging testicles is another change, signaling the production of viable sperm. Tarsal glands on the inner surfaces of their hocks (on hind legs) also enlarge, beginning to produce a viscous fluid containing musk. This musk is carried to ground scrapes by drenching the tarsal glands with urine while pressing them together to squeeze out the musk. While doing this, some bucks wag their rears bucks from side too side, appearing to be doing a hula dance.
Certain glands beneath the scalps of all antlered bucks (between their antlers) also become active, producing an acrid musk carried by a syrupy fluid that oozes down both sides of a buck’s head and down onto its neck, producing the rows of vertical wrinkles in fur most common on necks of dominant breeding bucks. This musk, seemingly most intense on dominant breeding bucks, is rubbed on antler rubs and branches or evergreen boughs overhanging ground scrapes during phase II of the rut, likely identifying the dominant buck that made these breeding range markers and reminding bucks that smell it they are in a perilous location.