Predicting the 2018 Whitetail Rut

As most experienced hunters can attest, the rut is a fickle thing – seemingly appearing in fits and bursts, at different times of the year, and in different locations. These inconsistencies in rut experiences have led to plenty of theories and confusion regarding the timing of the whitetail rut.

So, when will the whitetail rut occur in 2018?

The answer to that question depends largely on who you ask, because when it comes to the timing of the rut, hunters and biologists are often talking about two different things. Hunters are typically interested in understanding when the peak of daylight rutting activity will be, with grunting, fighting, and chasing filling the woods. On the other hand, biologists focus on the peak of actual breeding, which is what follows the grunting, fighting, and chasing.

These are two very different things. To understand the timing of the rut, an examination of both perspectives and all theories is warranted.

The Photoperiod Theory
When it comes to the timing of the rut and what triggers it, there are two prominent schools of thought – one being that the rut is lunar based, the other focused on photoperiod. To an overwhelming degree, most biologists and whitetail experts point to the later being true, stating that the timing of the actual rut (peak breeding) in most locales is not variable nor impacted by lunar factors. In fact, according to most scientific studies, peak breeding appears to be consistently in mid-November year after year.

According to a publication from The Quality Deer Management Association, “The bottom line is northern whitetails have a narrow breeding window to optimize doe and fawn health and survival. This is why numerous studies across the northern United States and Canada looking at conception dates show very little year-to-year variation. In fact, these breeding dates are amazingly consistent from year to year – regardless of moon phase, weather patterns, or other variables.”

QDMA Director of Communications Lindsay Thomas Jr. agrees with the science.

“The science on this is decisive. A significant number of scientific, peer-reviewed studies have shown the timing of the rut in any particular location is triggered by photoperiod, or day length – not by the moon, or temperature, or anything else. I think hunters often confuse visible rut behaviors, like chasing and grunting, with the peak of breeding. When you document breeding dates in a location, they actually change very little year to year, even though the dates of peak rut behaviors might vary. That’s because weather, moon phase and food sources – things that fluctuate widely year to year – affect deer movement patterns. But even when the weather reduces deer movement, you find that breeding still takes place the same time it normally does. If a doe is coming into estrous, a warm front isn’t going to change that.”

Rod Cumberland, a deer management biologist out of New Brunswick, conducted a study around this topic examining a data set of more than 1,600 does to determine conception dates. The chart below, produced by the QDMA as well, illustrates the results of that analysis, which led to the conclusion that peak breeding is very consistent.

“Our analysis revealed that the relationship between annual breeding dates and moon phase chronology was highly variable. Therefore, we believe it is not necessary to revise the conventional understanding among deer biologists that breeding dates are primarily influenced by photoperiod (day length) and are relatively consistent among years within a particular population.”

Many prominent whitetail hunters, such as Bill Winke of Midwest Whitetail, back this up with anecdotal observations.

“I have not seen a rut predictor that was actually more accurate than the calendar.  The rut is triggered by photoperiod – the amount of sunlight in each day. As the season progresses, that triggers the rut at pretty much the same time every year. You may see more behavior on certain days than others related to weather or hunting pressure, but the actual conception dates of the does are pretty consistent from year to year. Missouri recently did a study back-dating fetuses from late season harvested does and they proved that over a three year period the peak breeding date (the date when the most does were in estrous) was November 15 plus or minus one day. I always like to hunt during the week that starts ten days before the peak. In this case, that would be November 5 – 12. It is tough to beat that time frame.”

Echoing similar sentiments,with a unique twist, Mark Drury of Drury Outdoors explained on the Wired To Hunt Podcast that he believes the rut happens at the exact same time each and every fall.

“What part of it is exposed is when the full moon hits within that month based on daylight activity. The moon, in my opinion, exposes the daylight portion (of the rut) different each year depending on how the full moon falls. That’s why you see the variance in ruts that are intense versus not. If it exposes during the seeking phase (early November), you’ll go ‘oh man, this was an awesome rut.’ However, if the moon exposes the lockdown (mid November), you’ll think it’s a terrible rut.”

According to Drury, if you want to predict the very best daylight movement during the rut, look for those dates during the traditional rut timeframe (late October into the first two weeks of November) that coincide with the days surrounding the full moon.

The Lunar Theory
Despite this strong scientific consensus, an alternative theory maintains a rabid base of believers who favor the lunar rut idea popularized and developed by wildlife biologist Wayne Laroche and Charles Alsheimer. The Alsheimer/Laroche theory stems from 20 years of their own research.

“It is based on a model that links cyclical changes in the Earth’s solar and lunar illumination to the whitetail’s reproductive cycle. Laroche and Alsheimer hypothesize that sunlight and moonlight provide environmental cues that set, trigger, and synchronize breeding.”

This explanation, found in Deer & Deer Hunting’s annual rut calendar, goes on to describe how Laroche’s use of a computer model allowed them to analyze astronomical data, field observations and measurements of light, and in turn to develop a prediction of rutting activity. Per this research and modeling, Laroche and Alsheimer have theorized that the second full moon after the autumn equinox each year triggers the peak in rutting activity, leading Laroche and Alsheimer’s predictions to revolve around what is widely known as the “Rutting Moon”.

This year the Rutting Moon is earlier than usual, falling on October 24^th. In 2017 it was on November 4^th, in 2016 it was on November 14^th, in 2015 it was on October 27^th, and in 2014 it was on November 6^th.

According to the lunar theory, this timing of the Rutting Moon points to the beginning of rutting behavior taking place earlier than usual. According to Alsheimer’s lunar calendar, major seeking behavior is predicted to pick up around October 22^nd and continue through the 27th, when major chasing hypothetically would then begin. This peak in visible rutting activity is predicted to go through November 3^rd or 4^th, when the tending or breeding phase would kick into gear and continue through the middle of the month.

What might this mean for hunters? If you believe these predictions, it would mean that the last couple weeks of October will be better than normal and the first couple weeks of November will be worse than normal. According to the calendar, the best visible rutting activity and hunting should occur sometime between October 22^nd and November 4^th. This is when the majority of seeking and chasing will be happening, which is in fact the rutting behavior that hunters are most interested in seeing.

Rut Timing In The South
If making sense of these two different theories isn’t confusing enough, folks in the South have an even greater challenge as timing the rut below of the Mason-Dixon line seems to be much more variable. Charles Alsheimer previously tackled this topic as well.

“Southern whitetails don’t face the harsh winters and brutal conditions that dictate when Northern whitetail fawns must be born to ensure they are large enough to survive severe winters. Harsh cold and deep snows aren’t part of the Southern equation, so weather isn’t a factor for fawn births. Therefore, the South’s rut appears to be driven by less obvious factors, such as climate, genetics, nutrition, day length, moon phases and doe-to-buck ratios. It’s crucial to check with a local biologist to find out what month the rut typically occurs at a specific location.”

Making Sense of It All
After 10 years of gathering my own data, tracking these predictions, and studying the science, I’ve come to a few conclusions.

In regards to the Laroche/Alsheimer theory, I’ve found that my own personal observations have only on occasion matched these predictions. For example, in 2010 and 2013, when a “trickle rut” was predicted, I did see noticeably less daylight rutting activity, and the activity I did see seemed to be much more sporadic and spread out. In 2011, 2012 and 2014, when a more typical rut was predicted, I did see a more concentrated and intense amount of rutting activity during the first few weeks of November. On the other hand, 2016’s rutting activity was predicted to be later than usual, but I actually saw more activity early. This is, of course, only anecdotal.

In almost all these years though, I saw the most intense rutting activity happening during the first two weeks of November. Given these observations, similar reports from other avid hunters, and the overwhelming consensus among the scientific community, I’ve conclude that the timing of the breeding cycle and rut is quite consistent, regardless of moon.

As the studies have repeatedly shown, fetus tests indicate that the majority of breeding in the North almost always occurs around mid-November, regardless of moon or other factors. It should be noted that this breeding occurs on a bell curve, so every year there will be some breeding of does occurring earlier and some later. In general, though, the largest percentage of deer are getting bred somewhere around the middle of the month. This means most seeking and chasing – and the best hunting – typically occurs during the week or two preceding that.

I believe that this mid-November peak breeding date generally holds true, and that the two preceding weeks will almost always be the peak of seeking and chasing. I also believe it’s possible that other factors, such as the moon, temperature, barometric pressure, or precipitation, might impact the visible intensity of that activity during daylight. I look at these factors as intensifiers or dampeners of daylight movement, but not factors in the actual timing of breeding.

While I’m always curious to see what the lunar predictions indicate each year, I’ll still be focusing my heaviest hunting efforts on the first two weeks of November. Regardless of conditions or other predictions, I’ll be hunting every day during that stretch.

If by chance the weather, moon, or a fortune cookie point towards a higher chance of success, I’ll certainly take it. At this time of year, nothing predicts your chances of seeing rut action more accurately than being in the woods. When sweet November hits, it’s time to hunt.

I’ve been sharing a modified version of this annual rut prediction article on Wired To Hunt for nine years. If you’re interested in comparing your previous rut experiences with predictions from past years, follow the links below.
2017 – 2016 – 2015 – 2014 – 2013 – 2012 – 2011 – 2010