A dominant breeding buck working on a ground scrape.
Rut Phase II, the buck breeding range establishment phase, is least understood by whitetail hunters, yet no period of the rut receives more attention from hunters. Normally triggered by a certain low temperature at night in mid-October, 32 degrees in Minnesota (60 in South Carolina), it begins with a frenzy of making antler rubs and ground scrapes by all antlered bucks. More than 90% of rubs and scrapes are made during this period. It is commonly believed all this buck activity can only mean one thing: breeding is in progress (They’re ruttin’. Yahoo!). This belief in turn triggers another frenzy: that of bowhunters using doe-in-heat buck lures. Contrary to this belief, the first of the three two week periods of whitetail breeding is triggered on the same date annually by a specific ratio of darkness to sunlight (photoperiodism) in early to mid-November (a bit later in the south than in the north). This is absolutely proven by the fact that following the usual seven-month period whitetail does are pregnant, 85% of fawns are born in May, 10% in June and 5% in July. Breeding begins only when it becomes obvious bucks have quit renewing ground scrapes in early November.
This phase of the rut is the only one triggered by a certain temperature at night (rather than photoperiodism), making it difficult to predict exactly when the characteristic buck signs of this period will first be discovered in your hunting area. Whitetail fur is part of the equation that determines when it will happen. By mid-October, the scant red summer fur of whitetails has been replaced by a heavy two-layered tan coat that enables them to survive the coldest winter temperatures of their regions. If temperatures are unseasonably warm during the second half of October, heavily furred bucks are reluctant to exert themselves greatly, temporarily delaying or quitting making antler rubs and ground scrapes until temperatures return to normal. If unusually warm temperatures continues until breeding normally begins, the year will be remembered by hunters as one of very few rubs and scrapes.
So why do bucks make rubs and scrapes? It’s the same reason many species of wildlife, even our pet dogs, mark their home ranges with urine: to warn others of their species to keep out — each animal determined to have a certain amount of space of its own and this being nature’s way of assuring each animal will have adequate food. The degree to which marking ranges with urine is respected by whitetails is different among bucks and does. Mature does with young vigorously defend their separate home ranges from being used by any other doe or any other fawn of either sex, driving them away with vicious kicks and furious pursuit. Mature bucks (2-1/2 years of age or older), however, are allowed to wander through or live within doe ranges without interference.
The number of mature bucks living in a square-mile, typically 3–5 of them, and their pecking order (which may change after shedding velvet in September) is quickly settled early each spring. Though antlerless and less combative then, brief skirmishes of a different kind are not uncommon among them — bucks with drooping ears nimbly prancing about on hind legs while pummeling one another with forehooves. Though their larger home ranges necessarily overlap, they live with relative peace among one another until after they have shed velvet in fall and their bodies and temperaments are being transformed to make then gladiators anxious to determine which of among them is most superior physically and will thus pass along its superior genetics while breeding is in progress.
Part of this transformation includes an increasing production of aromatic musk in certain glands of antlered bucks: tarsal glands located on the inner surfaces of the hocks of their hind legs and smaller glands located beneath their scalps. Emissions of fluids containing scalp musk are especially noticeable on dominant breeding bucks, oozing down both sides of their heads onto their necks and causing a series of deep vertical wrinkles to form in the fur on the sides of their necks. Musks now become the primary odors of ground scrapes and antler rubs — antlered buck range markers made after mid-October to identify and delineate their home ranges, now considered intended breeding ranges.
Using their forehooves, antlers, musk glands and urine, antlered bucks make remarkably visible and readily smelled (by deer) breeding range markers. With forehooves, they paw away turf, leaves, moss and/or snow to create bare patches of soil (ground scrapes) adjacent to much used deer trails within the home ranges of does living within their individual buck ranges. They then position all four hoofs on each scrape and while pressing their tarsal glands together to squeeze out musk they urinate on their hocks to carry the musk to the ground. Some bucks wag their rumps from side to side while doing this to express greater quantities of musk.
Scrapes made by dominant breeding bucks generally have certain unique characteristics. Though they may be small at first, they end up being larger than those of other bucks — typically three or more feet in diameter. Some I have measured were as large as 10 feet in length or 10 feet in diameter. They commonly appear to have been made by bucks that were enraged, soil, turf, moss or leaves pawed as far as ten feet to one side. To add further to their conspicuousness, especially as breeding draws near, dominant breeding bucks mangle branches or evergreen boughs overhanging their scrapes and rub scalp musk on them. If overhanging branches are not available, some big bucks will make do with an adjacent young evergreen tree or a woody multi-stemmed shrub, vigorously stripping off boughs and much of the bark from the tree or mangling branches of the shrub, then lacing the remains with scalp musk.
Buck checking his scent on an antler rub and ground scrape.
As explained in a recent blog, antler rubs are as important to bucks as home or breeding range markers as ground scrapes. After painstakingly stripping bark from a tree trunk to bare a patch of brightly colored wood high enough above the ground to make it visible great distances away, bucks carefully rub acrid scalp musk from the sides of their heads onto the bared wood. After doing this, I have often observed bucks lick the rub (or a bare section of a branch overhanging a scrape) as if using their sense of taste to determine when they have deposited enough musk on it. Unfortunately (for hunters), rubs aren’t ordinarily renewed often enough to be preferred stand sites.
Peaking testosterone causes all antlered bucks to be restless during this period. After returning to their individual bedding areas between feeding and range marking hours, they sometimes satisfy their growing aggressiveness by battling tree trunks that will bend (become the loser) but not break. Yearling bucks prefer one-inch-diameter tree trunks, 2-1/2 year-old bucks prefer 2 to 2-1/2 inch tree trunks and 3-1/2 to 6-1/2 year-old bucks prefer tree trunks three or more inches in diameter. Clusters of newly made antler rubs are thus common identifying signs of buck bedding areas after mid-October.
The trouble is (for bucks), for each antlered buck marking an intended breeding range in a square-mile there are 4–7 others doing the same thing. This would be a recipe for pandemonium if not for the goal of the most dominant buck of each square-mile. Growing more hostile as each day because of peaking testosterone, it has no intention of allowing all those other antlered bucks to remain in their intended square-mile breeding ranges while does living there are in heat.