Moon Phase's - Fact or Fiction

Over the last ten years, one frequently asked is about the moon and its influence on the white-tailed deer. I'm paraphrasing here, but the question generally is, “What are your feelings about what role the moon plays in deer activity and the rut?”

For many hunters the question about planning their hunting time and strategies around the status or influence of the moon's cycle or phase has become of paramount importance to them. Some even remain in camp rather than hunt if they feel the moon's cycle isn't at the right stage to encourage movement or rut activity. How wrong is that?

I agree that the gravitational pull of the moon is strong and that its "pull" affects many life forms and natural wonders in our world. There is no denying that the moon's pull affects the tides in the ocean, for instance. But does the moon's lunar cycle play an important enough role to make hunters plan their entire deer season around the stages of its cycle? This is the question that needs to be answered once and for all.

Many deerstalkers are convinced that significant whitetail activity, especially rutting behavior is highest during specific moon phases. Many hunters tell me that they are persuaded beyond doubt that they see more deer moving during mid-day after particularly dark nights, solely due to the cycle of a new moon.

The assumption is that dark nights make it difficult for deer to move easily within their range forcing them to move more during daylight hours. Still others are certain the primary rut takes place during the rutting moon that is close to the second full moon after the autumn equinox. Many devoted hunters have been convinced by so called "authorities" that lunar phases are critical for timing deer movement during specific moon phases, but believe me there are a lot of facts that suggest that is simply not the case.

Researchers from the University of Georgia's School of Forest Resources have examined the moon's lunar phases and how it affects the timing of the white-tailed deer's breeding behavior. They wanted to find out if deer hunters who strive to bag a buck should concentrate their hunting tactics during a full, new, or partial moon. They also wanted to know if any of the moon's cycles actually make a difference at all.

David Osborn, Dr. Karl Miller, and Robert Warren, UGA wildlife research biologists, used breeding date data from a variety of state wildlife agencies to make a determination if moon phases had any effect on whitetail doe estrous cycles and, therefore, the rutting activities and behavior of bucks.

Breeding dates were gathered from captive deer in four states and more than 2,000 free-ranging does in seven others. Believe it or not, this information took from three to nineteen years to compile. It was then compared to lunar cycles throughout the birth date ranges.

"We would expect annual breeding dates for a population to be similar if the calendar date and therefore the same length of daylight, was the driving influence," explained Osborn. "We would expect annual breeding to be less similar if moon phase is the driving influence because a particular moon phase might vary as much as 28 days across years."

The fact is, and many of you have heard me preach this for years, biologists and scientists have long agreed that photoperiod (the length of daylight), is the overriding influence on whitetail breeding activity than any other factor. There isn’t any bones about it the evidence is quite clear: Scientists and biologists agree that the phase of the moon has virtually nothing to do with the timing of whitetail breeding activity.

For years, state wildlife biologists all over North America regularly and confidently use calendar dates to help deer hunters plan their vacations and time afield to match as closely with the peak rut activities as possible. The state of Virginia, for instance, shows November 15th as the peak of the rut, while Minnesota hunters need to be in their deer stands the first week of November. In my first book I listed the prime rutting dates in most of the northern states and provinces as November 10th through the 15th, give or take a few days on either end.

But while any of the dates provided can be used as reliable guidelines, they should not be taken as the last word on rutting activity. As I have often said, there are simply too many outside factors to consider. The rut can be delayed by extremes. We can relate this to women we know. If your significant other is worried about finances, material problems, children, or a host of other matters, she can become overly stressed. With this extra stress, it is not uncommon for her to miss or skip her menstrual cycle for a month, or in some extreme cases, longer.

The same principal holds true for other female mammals. If they are stressed (in the case of deer, they become stressed by the environment), Mother Nature steps in and prevents the doe from coming into heat. This prevents the doe from becoming pregnant and avoids the possibility of her losing her fetus or even her own life. Instead, the doe skips a cycle or two and waits to come into heat after the stressful conditions have passed.

Remember the word extremes. Not much can change the rut but extremes in certain conditions can. For instance, if there is a very early and deep snow fall, unseasonably warm or frigid weather, lack of other quality and nutritious vegetation, or even an absence of mature breeding bucks within the range, a doe becomes stressed enough to skip a heat cycle. Other than the above, the rut usually takes place right on time across North America.

Matt Knox, Virginia's deer project leader said, "It's really impossible to choose a specific date because of a variety of outside factors. I'd say that November 15 is a pretty consistent date for the peak, but it's going to vary a few days on either side."

Dr. Warren of the University of Georgia said, “The timing of the rut is influenced by various factors, but moon phase doesn't appear to be one of them.” The study found that there was no hard evidence to support theories that breeding behavior is controlled by lunar cycles. Dr. Warren says weather, food availability, human activity, and a variety of other factors all play a role in the timing of the rut, but breeding activity typically happens within a relatively predictable period, no matter what the moon phase happens to be. The length of daylight, more than anything else, controls the rut.

New England deer biologist Gary Levigne, who works with Maine's Department of Inland Fish and Game, contributed to the UGA study and he also echoed the theory that the “timing of the rut is based almost entirely on photoperiod.”

Again, if you have ever heard my seminars or read my articles or read the rut chapter in my book Whitetail Strategies, I strongly emphasized that Mother Nature (perfect in her design) has planned through evolution to perpetuate the species as her priority. That means making sure that the fawns are born during times of good weather and good sources of food availability for the doe.

The bottom line is that evolution has developed a plan where the fawn survival rates are maximized. If fawns are born too early in the year, when it may still be too cold or wet, the does may not be able to gather enough food for themselves to provide vital nutrition in their milk. If they are born too late, the fawns may encounter early snowfalls that are too deep and don’t have the time to become healthy enough to survive the oncoming winter. So, the 28-day disparity that would coincide with the moon phase theory would mean that fawns could be born 28 days before or after the peak fawn birth date, and as any hunter who notices when does drop their fawns, birthing takes place pretty much the same time every year

It is important to note that the while the rut may be around the same dates in Montana as they are in Maine, breeding activity in the more northern latitudes like Saskatchewan and Alberta typically take place over a short period of time--but activity tends to be a lot more intense.

On the other side of the coin, deer that live in extreme southern states like south Texas and Florida, have a much longer breeding season, sometimes lasting as long as four or more months. This simply means trying to pin down an actual date of the peak rut may be much more difficult in southern areas because of a less concentrated rut activity around a specific time. But the general conviction among most whitetail experts, and almost all of the biologists and scientists I have talked with, is that no matter where deer live, they don't seem to pay attention to the phase of the moon.

While the question about whether the breeding activity is influenced by the gravitational pull of the moon has been answered there is still another question hunters regularly pose to me, what about the moon's influence on other deer activities? Do deer feed more during the day during a new moon phase because they can't gather enough forage during extra dark nights? And does the moon's lunar cycles have any effect on deer movement in general? Well, not according to my deer observations over the last forty years, and not according to the many biologists that I have talked with. No one I know or have interviewed has found any distinct or predictable patterns in wildlife activity during various phases of the moon.

Deer movement in general might remain fairly consistent if weather, hunting pressure, and food sources remain constant, but the chances of that are slim as deer live in a world of constant change.

Most biologists agree that the most influential factor not only on breeding patterns but also on life is the availability of high-quality forage. Again, Mother Nature—perfect in her design—makes sure that the driving force behind the life of every doe is procreation, and they respond to changing food sources in order to provide the maximum amount of energy for their fetuses or fawns, depending on the season.

Both private and public studies have demonstrated without question that breeding activity can take place either very early or very late, depending on the quality of the mast crop. When the mast crop is heavy and very early, does come into heat earlier than normal. If there is a total mast crop failure, then breeding activity can be delayed sometimes by a month or more.

So with all that said, what should a hunter do? My advice is as it has always been. A good day afield hunting deer beats one at home! I strongly recommend that hunters forget worrying about what effects the moon's cycle or phase plays in their deer hunting and all the hype that goes along with it. You can take this advice to the deer hunting bank because the information I just shared with you is a good as gold -- hunt the calendar, not the moon. Remember this - researchers across the country agree: Whitetail breeding behavior is controlled far more by photoperiod, not the moon phases.

I start hunting as soon as the season opens, and like many of you I hunt right through to the end of the season as well. As I have mentioned many times in my seminars, if you happen to be on the way to work and you see a big buck out and about at 10 in the morning, call in sick! The rut is on and you need to spend all day in the woods if you can.

So there it is, my feelings about placing too much reliability on the moon cycles or phases and deer activity and the rut. In a few words - it's poppy cock.

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