As we have done every year since the early 1990s, the Deer & Deer Hunting Whitetail Calendar includes the “Whitetail Rut-Predictor.” This system has been featured in several D&DH articles over the years by our late contributing editor Charles J. Alsheimer of Bath, New York.
Watch Charles Alsheimer Explain the 3 Types of the Whitetail Rut
The Whitetail Rut-Predictor helps you plan when, where and how to hunt. The rut follows predictable stages of deer behavior. These changes dictate the effectiveness of hunting strategies. Scrape-hunting, for example, might be effective when bucks seek does, but it won’t work later during the rut, when most does are already bred or being tended.
Not every buck exhibits the predicted primary behavior on a given date. Several factors, including age, nutrition, health and genetics, can affect the time and extent to which bucks exhibit certain behaviors. The Whitetail Rut-Predictor represents peaks in the activities and “minors” of secondary activity.
The primary rut behaviors predicted in this calendar are “seeking,” “chasing” and “tending.” Feeding is a buck’s primary pre-rut activity. To take advantage of this, place stands near deer travel routes and feeding areas.
Here’s a closer look at the specific deer behaviors that can be predicted with what Alsheimer taught us about the whitetail rut:
The onset of each rut period is marked by a sudden increase in deer activity as bucks seek does. The trigger is not exactly known, but it might be a chemical signal from does approaching estrus.
Intense seeking activity makes for great stand-hunting. Bucks in this mode are also vulnerable to calling, rattling, scents and decoys. These bucks will often skirt the edges of swamps and forest transitions.
Chasing begins when a buck locates a doe that is near the peak of her estrous cycle. As the buck approaches, the doe runs, but not in all-out flight. She soon slows or pauses to look back for the buck, which won’t seek other does, and continues in pursuit. The buck occasionally catches up and tries to corner the doe. This can result in a long chase that continues until the doe lets the buck accompany her.
Stand- and still-hunting in a near-estrous doe’s home range can be productive, because several bucks could enter the chase.
After a white-tailed doe allows a buck to accompany her, tending begins. He beds and moves with the doe until she is bred. Tending, which ends abruptly, usually lasts about 24 hours. After the doe is bred, the buck seeks other does and the cycle resumes.
Tracking can be effective for hunting a buck tending a doe. Bucks also respond to grunt calls, because they seek to drive off other bucks. However, don’t expect a buck to go far from a hot doe to visit scrapes and scents.
Bucks in healthy herds with a balanced sex and age structure have well-defined social orders. In herds in which bucks reach 5-plus years of age, dominant bucks do most of the breeding. As the herd’s age structure is skewed toward young bucks, the youngsters become increasingly involved in the rut and breeding. As the doe-to-buck ratio approaches 1-1, seeking behavior and interactions between bucks are maximized. As the doe-to-buck ratio skews toward does, bucks spend less time seeking because females are readily available.
Seeking behavior begins abruptly and kicks off the rut about the time of the full moon, but not just any full moon, because day length is also involved. As chasing and tending increase, seeking behavior declines. Seeking can be expected any time during the rut when a buck finishes chasing or tending a doe. The peak of seeking occurs just before the peak of tending and breeding. Tending behavior and breeding peaks about the time of the new moon during the rut. The rut seems to end as quickly as it begins.
Effects of Latitude
The wobbling cycle of the Earth on its axis as it circles the sun causes seasonal changes by varying the amount of sunlight reaching the ground at different locations.
The link between diminishing day length and the rut’s onset is clear. However, it’s not simple. The breeding season is most intense and concentrated at Northern latitudes where the difference between day length during summer and winter is greatest. The breeding season lengthens the nearer deer live to the equator. This partly explains why the rut appears more varied in the southern United States.
Effects of Weather
Activities on the Whitetail Rut-Predictor calendar might occur several days early because weather can affect daylight amounts. Dense clouds shorten day length 15 to 20 minutes, and decrease moonlight intensity. Rain and snow block sunlight and moonlight by defraction and diffusion, preventing moonlight from reaching the ground. Storms can shorten daylight about 30 minutes and obscure almost all moonlight.
Intense rutting activity is often associated with storm fronts in South Texas and other Southern states, but not in Northern states. This activity is often attributed to low air temperatures or barometric changes, but light likely plays a major role. Air temperatures exceeding 55 degrees Fahrenheit usually decrease deer activity.
The Predictor’s Basis
The Rut-Predictor is based on a model that links cyclical changes in the Earth’s solar and lunar illumination to the whitetail’s reproductive cycle. It is hypothesized that sunlight and moonlight provide environmental cues that set, trigger and synchronize breeding.
A computer model was developed that uses astronomical data, field observations of rutting activities and measurements of light intensity to predict rut activity.
The Rut-Predictor hypothesis differs from conventional views. The general belief is that peak breeding north of the Mason-Dixon Line occurs each year about November 15. However, it has been observed that rut activity often falls to nearly zero by mid-November. The timing of peak rut activity could vary year to year by as much as three weeks at any given location.
If the moon is the timing mechanism for the estrous cycle, what sensory pathway in deer receives the cue? External stimuli fall into three primary categories: physical, chemical and biological. The great distance between Earth and the moon rules out any regular 28-day exchange of sounds, scents or chemical and biological materials deer can detect.
The moon affects the Earth’s gravitational fluctuations and nighttime illumination. Both factors create external stimuli that deer might detect. However, little evidence suggests deer or other creatures directly detect gravitational forces. Responses to those fluctuations are probably indirect. As a result, gravity’s effects were rejected as a stimulus for timing the whitetail’s estrous cycle.
Moonlight can be detected, especially by whitetails, which have eyes adapted for low-light vision. Light passing into the eye strikes the nerve-rich area in the back of the eye, causing electrical impulses to pass along the nervous system to various organs. Some impulses pass to the pineal gland in the center of the brain, providing input to the endocrine system. The pineal gland and related hormones are involved in or regulate the reproductive cycle. The pineal gland responds to light by increasing (with diminishing light) or decreasing (with increasing light) production of a hormone called melatonin. This, in turn, increases or decreases other hormones.
The fact moonlight changes the Earth’s illumination on a cycle similar to the whitetail’s 28-day estrous cycle, the fact whitetails have a sensory system that can detect moonlight, and the fact the whitetail’s endocrine system responds to light stimuli by altering levels of reproductive hormones argue against coincidence.
Peak Rutting Dates for 2018
The chart accompanying this article predicts whitetail activity for all areas north of the 35th latitude (shown on the map). Obviously, these predictions aren’t 100 percent set in stone, and they do vary depending on your proximity to the 35th latitude. In some region-specific areas, the peak of the rut will coincide more with the Southern rut predictions compiled by Jeremy Flinn (included in the November issue of D&DH).
But, if you have been following these rut predictions for the past 25-plus years, you will notice that the Alsheimer Algorithm has been right more times than it has been wrong.
All things being equal, the best dates for hunting this year’s rut in Northern locations will be:
2018 Seeking Phase:
- Begins Sunday, Oct. 21.
- Peaks Wednesday, Oct. 25.
- Fades out on Saturday, Oct. 27.
- 2018 Chasing Phase:
- Begins Thursday, Oct. 25.
- Peaks Wednesday, Oct. 31.
- Fades out on Friday, Nov. 2.
2018 Breeding Phase:
- Begins: Thursday, Nov. 1.
- Peaks: Wednesday, Nov. 7.
- Fades out on Saturday, Nov. 10.
Do not forget about the peak “minor times” when determining which days to take off from work and go hunting. The best minor times for each phase will be:
- Major/minor chasing: Oct. 25 to 27.
- Major/minor seeking: Oct. 28 to Nov. 2.
- Major/minor chasing #2: Nov. 3 to 7.
The so-called “second rut” action is predicted to fall during the first week of December, ending on the 8th, with an additional minor period occurring from Dec. 23 to Dec. 31.
Testing the Rut-Predictor
The Rut-Predictor has been well tested. For example, when whitetails from the United States have been brought to the Southern Hemisphere, where seasons are reversed, they shift from a November rut to a May rut. This is also reinforced by the fact whitetails in equatorial regions breed asynchronously throughout the year.
Interestingly, the only way to disprove this theory is to witness behavior that contradicts it, such as seeing most does breed within seven days of a first quarter moon. Failure to observe predicted behavior, however, proves nothing, because it might be caused by unrelated factors, such as poor visibility, bad weather or low deer numbers.
In snow country, breeding can be recognized by observing tracks. A buck tending a doe leaves a distinctive trail as he follows with his nose on the doe’s tail. A big buck track overlaying a lone doe track is a sure sign of tending behavior. Several such trails signify peak breeding. If you live where snow doesn’t fall and the deer population is relatively high, you might observe tending and breeding behavior directly.
To help predict breeding behaviors for your area, keep a daily log of fresh rubs and scrapes you and your hunting partners observe. For added accuracy, quantify your effort by recording how many hours of hunting are associated with your counts.