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NEW: Anatomy of the Rut:Real World Timing

Preorbital Gland
October 23, 2016

Anatomy of the Rut: Real-World Timing
(This is an excerpt from "Whitetail Tactics: Cutting Edge Strategies that Work" - click here to purchase an autographed copy)

The white-tailed deer breeding season, or rut, refers to the time frame when does are most fertile and receptive to accepting the amorous intentions of male deer. Unfortunately, there is a wide array of misinformation, rumors, and long-held myths about this important subject. Two of the most common held erroneous viewpoints are that the rut takes place only during cold weather and the rut only lasts for a short period of time during November. The fact is that neither of these two notions is accurate. I can assure you that since I began hunting in 1964, I have discovered that rut information handed down from old-timers generally consists of unintended distortions, half-truths and, in some cases, unequivocal misinformation.

For instance, the whitetail’s rut lasts for months. At my seminars, many people are astonished when I tell them that as long as a buck has antlers attached to his head and a doe has not been successfully bred, both are willing and able to breed whether it is in October, November, December or even later.

The genesis of each phase of the rut occurs specifically with relationship to specific dates within the four latitude zones within the United States. If you include Canada, there are six latitudinal zones and if Mexico is added, there are nine. Latitudes are invisible horizontal lines that depict the angular distance, in degrees, minutes and seconds of a point north or south of the Equator. They are also referred to as parallels. Within each of the parallels in North America the rut takes place whether it is cold or warm outside, with surprising regularity. Cold weather only helps to generate daytime activity. In other words, when the weather turns cold, bucks are more likely to move about much more searching for does throughout the day than during warmer temperatures. The chilly weather spurs their libido and makes them more inclined to feel romantic. This phenomenon can cause the breeding cycle of white-tailed deer to take place over a much longer period of time than most believe.

The internal trigger that causes deer to be aware of the onset of the rut is the pre-orbital gland located in the corner of a deer’s eye. It senses waning light levels, or photoperiods, that begin in early autumn. The preorbital gland is a paired exocrine gland that is found in a majority of hoofed animals, which is similar to the lacrimal gland found in humans. The preorbital glands are black trench-like slits of nearly bare skin extending from the medial canthus of each eye, which are lined with a combination of sebaceous and sudoriferous glands. They produce secretions that contain pheromones and other chemical compounds. All ungulates frequently deposit these secretions on overhanging branches, licking sticks, twigs, and grass as olfactory communication messages to other deer.

The preorbital gland serves different roles in different species. Pheromone-containing secretions from the preorbital gland may serve to establish a buck or doe’s hierarchy within its herd. As a buck or doe prepares for breeding season, they will mark vegetation within their home range with preorbital scent. Because of its critical role in scent marking, the preorbital gland is usually considered a Type A scent gland. Some biologists believe the preorbital glands may produce antimicrobial compounds to protect against skin pathogens.

The various secretions of compounds and chemicals trigger a buck’s brain to recognize the start of the rut and his testes begin to enlarge and descend, becoming more visible. With each passing day of waning light the demeanors of deer, particularly adult bucks, go from tolerant and benign to irritable and aggressive. By the time the primary phase of the rut kicks in, a buck’s testes reach their greatest size.

No matter where whitetails roam, the rut corresponds closely to the time when most female deer are fertile and, therefore, most apt to be successfully bred. If, for whatever reason, a doe is not successfully bred during the peak rut, she will come into her estrus cycle every twenty-eight to thirty-two days. The exception to this rule is if a doe undergoes unusual stressful situations from outside influences. In this case, the doe will skip one of her cycles.
All adult female deer are bred between the autumnal equinox and the vernal equinox, the two nights each year where day and night are the same length that kick off the spring and fall seasons, respectively.
The intensity and length of the entire whitetail breeding cycle, three phases of the rut, differs depending on the latitude in which they live. Deer living in the most northern latitudes (above 60 to 70 degrees north) breed sooner than those living in the most southern latitudes (25 to 29 degrees south). Therefore, it becomes evident that the breeding cycle of deer is definitely not initiated simply by cold temperatures. As I stated, it is controlled, or in the very least set in motion, by photoperiodism. At the onset of the breeding cycle, photoperiodism stimulates another of the primary glands of the white-tailed deer, the pituitary gland. It is located in the brain. This gland also produces the chief hormones that control antler growth. Once again, the brain releases chemicals and they, in turn, stimulate both male and female sex glands.

Different latitude zones throughout North America experience photoperiodism at different times. This affects the dates of the primary breeding cycles, causing them to vary accordingly. For instance, the northern parts of Canada and Alaska fall within latitudes of about 60 to 70 degrees north. The primary breeding cycle of deer in these zones is considerably earlier than all parts of North America south of the 59-degree north line of latitude. From about 51 to 59 degrees latitude north, which includes the most southern parts of Canada, the rut varies from slightly different to somewhat different than it is from 45 to 50 degrees north latitude.

In the most northern sections of the United States and southern most regions of Canada, the latitudes fall between about 46 to about 52 degrees north. This area includes the northern tip of Oregon, Washington, the Idaho panhandle, Montana, the extreme northern portion of Wyoming, North Dakota, northern South Dakota, southern Minnesota, northern Wisconsin and Michigan, the northern portions of Maine. The primary rut in these states takes place approximately the first week of November as photoperiodism happens slightly earlier than its southern neighbors.

The latitudes between 40 degrees north and 45 degrees north include most of the Northeast, New England and mid-west states. It also includes most of Oregon, northern California, Nevada, Utah, Colorado, lower Idaho (all points south of the Pan Handle), a majority of Wyoming, southern South Dakota, Nebraska, Iowa, the extreme northern tip Missouri, the northern half of Illinois, Indiana, and Ohio, and as note above, a majority of Pennsylvania, all of New York, northern New Jersey, Connecticut, Massachusetts, Vermont, New Hampshire, and the southern portion of Maine. Within the overall two-week or so period of the primary rut, there are about five peak days off breeding activity that occur within the general latitudes of 40 to 45 degrees north. The peak days of breeding activity reliably occur from November 10th to November 15th, with the 13th and 14th being particularly high activity days. These days can also be peak breeding days in the latitudes of 37 to 50 degrees north and from the longitudes of 50 to 125 degrees west. However, nothing about dates is written in stone. When I provide dates, they can vary by twenty-four to thirty-six hours on either end of the dates given throughout any latitude or longitude.

The zones between 35 degrees north to 39 degrees north include southern California, southern Nevada, Utah, Colorado, northern Arizona, New Mexico, the northern tip of Texas, northern Oklahoma, northern Arkansas, Kentucky, Tennessee, southern Missouri, Indiana, Illinois, Ohio, West Virginia, Virginia, the upper portion of North Carolina, Maryland, Delaware, the southern tip of New Jersey, and the lower portion of Pennsylvania. The primary rut takes place in these areas approximately the last week of November.

In the zones from 30 to 34 degrees north, which includes the southern tip of California, southern Arizona, and New Mexico, the heart of Texas, southern Oklahoma, and Arkansas, most of Louisiana, Mississippi, Alabama, Georgia, South Carolina, and the northern most tip of Florida and north tip of the country Mexico, all experience a later primary rut. The dates can vary slightly in the southernmost areas in these latitudes, but the primary breeding cycle generally takes place in late December to early January. All zones that fall between 25 to 29 degrees north include northern Mexico, south Texas, the southern most portion of Louisiana, and a majority of Florida. In these states, photoperiodism occurs later than anywhere north of the 29 degree north and, therefore, the primary rut takes place later than anywhere else in North America. It can occur from mid- to late-January.

The end result is that the primary rut occurs at different times in some portions of the United States, Canada, and Mexico. However, for a big portion of the United States and southern Canada (where most whitetail hunting takes place), the primary chase period, immediately followed by the primary peak of the rut takes place as mentioned above -- November 10th to about November 20th give or take a few days. You can take that statement to the deer hunting bank!
While most of the time these rut dates can be relied on as “written-in-stone,” there are occasional extenuating circumstances when the breeding cycle of a whitetail doe can be delayed and, in rare situations, prevent the rut. A doe’s reproductive cycle can be delayed, skipped, or halted, by a variety of factors including but not limited to poor nutrition, extreme cold temperatures, overpopulation levels within her range, scarcity of food, drought, heavy predation from wolves or coyotes, old age, poor habitat, and even heavy hunting pressure.

Some of these factors can actually improve hunting, however. For instance, if a doe skips a cycle, she may come back into heat 28 to 32 days later. This can cause a very pronounced post-rut frenzy period. I have witnessed this several times. When this happens, it usually takes place in mid-December. Bucks, frustrated by the abbreviated primary rut in November, now throw caution to the wind and seek out receptive does throughout the day and night. This increased rutting activity accounts for a high level of buck sightings by hunters. A delayed heat cycle by mature does can be one of the most exciting ruts a hunter will experience.

This information is meant to provide hunters with a clearer picture of exactly how the rut is initiated and what factors contribute to it happening during specific time frames. By understanding what I have shared with you here and using it properly, you can increase your chances for bagging a trophy-class buck ten fold!


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