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Does the moon and weather affect deer movement? Or the rut?
Outdoorsman have been trying to figure out how to predict deer activity for years. Hunters want to know how meteorological conditions affect deer so they can apply tree things: I. when deer are most active; 2. where to find deer, and 3. when the rut occurs. There are several game activity tables on the market that predict daily deer movement based on the gravitational forces and position of the moon in relation to the earth's latitude and longitude. There are other tables that predict when deer should be most active each month based on the amount of light, the position, and other factors of the moon. There are also a number of writers and deer researchers using the moon to predict when the rut should occur. Their predictions are based on the belief that the amount of light from the moon affects the estrus cycles of white-tailed deer.
I have spent the last eight years researching deer activity, meteorological conditions and lunar factors in an effort to find out if the moon really does affect deer activity. During the study I recorded the daily temperature, dewpoint, windchill, barometric pressure, wind speed, wind direction, cloud cover and type and amount of precipitation. I took note of several lunar factors, including the position, amount of light, speed and gravitational pull of the moon. I also recorded the number of deer I saw on an hourly basis, where I saw them and what they were doing. I also recorded when rubbing, scraping and breeding occurred. Then I checked the results of my studies against the findings of several well known deer biologists.
Daily Deer Activity
After I had recorded all my data every year, I looked for a correlation between the various meteorological and lunar factors and deer activity. Then I compared findings with several daily game activity tables. What I found was that many of tables predicted approximately the same days and times, but because they didn't take into account the daily meteorological conditions, there were times when no deer were seen at the times predicted. But that was to be expected, because I knew the weather would affect daily deer activity. Many of the tables were ineffective, because they didn't take into account all of the lunar factors that affect when and where deer are most likely to be active. In order to properly predict deer movement on an hourly basis you can't rely on just the position and gravitational pull of the moon.
Monthly Deer Activity
Next I checked my findings against the predictions of the monthly game activity tables. Because these monthly tables take into account more than the phase and gravitational pull of the moon, I found that they were effective at predicting when deer were most active each month. However, I found that meteorological conditions - the amount of light, temperature, windchill, wind speed and precipitation - often override any affect the moon might has on deer. I also found that food availability, the rut and hunting pressure can override any affect the moon might have on deer.
To find out if the deer researchers and outdoor writers were right about when the rut should occur I compared their predictions against the breeding dates of over 1,600 wild deer. Over the course of eight years, there was no correlation between the breeding dates of the wild deer and the dates predicted. I also asked several deer breeders if they thought the moon influenced when their does were bred. The deer breeders all told me that their deer bred at approximately the same time each year, and that there was no correlation with peak breeding and the phase of the moon. In the spring of 2001 Dr. Karl Miller and several other researchers presented the results of their study on peak breeding dates at the Southeast Deer Study Group. After checking the breeding dates of approximately 2,500 whitetail does, in eleven different states in both the northern and southern United States, they found no correlation with peak breeding and the phase of the moon. This leads me to believe that the moon has very little influence on the timing of the peak of the rut each year.
However, that doesn't mean you can't predict when the rut will occur, because you can.
Biologists in most states have conducted studies to determine when peak breeding occurs in their state. What they have found is that whitetail breeding dates are dependent on the weather and the length of the summer growing season. The arrival of warm weather and spring rains often determines how early fawns can be born; the arrival of cold weather and fall rain/snow often determines how late fawns can be born. The age and size of the fawns during the fall often determines how many of them survive, which in turn determines when peak breeding should occur. Because much of the whitetail range is in the north, where spring comes late and the growing season is short, the breeding season is short, with the result that peak breeding must occur at the appropriate time. In general, peak breeding of white-tailed deer above the 4Oth parallel occurs during the second week of November - every year. But, the farther south the deer live, the longer the summers are, and the more difficult it is to predict exactly when peak breeding occurs. For example peak breeding for deer between the 36th and 40th parallel may occur anytime from mid-November to mid-December.
Because climatic differences like seasonal rains, floods and droughts, and warm coastal weather affect growing seasons, breeding dates vary in different regions.
Breeding of deer in much of the southeast United States occurs during November and December.
However, there are several exceptions. Peak breeding of deer along the lower Mississippi basin in Arkansas and Louisiana may occur in December and January, so that their fawns are born later, after the spring floods. In southwest Louisiana peak breeding occurs from mid-September to late October. Along the Mississippi River Delta, in the Atchafalaya River Basin, and in the parishes of southeast Louisiana peak breeding occurs in December and January. Peak breeding in norhthwest and central Louisiana occurs from mid-October to Mid-November. Deer along the Gulf Coast in Alabama may breed from December to February. Deer in Florida may breed from July through February, depending on which geographical region they are in. Deer along the Atlantic coast in South Carolina and Georgia may breed earlier than deer farther inland, because coastal areas warm up earlier. Peak breeding of deer in eastern Texas may occur at the same time as the peak breeding of deer above the 40th parallel; mid-November to mid-December. Peak breeding of deer in the southwest United States and northern Mexico, including deer in northern, southern and western Texas, may breed from mid-November through January.
The best scientific data I have suggests that the phase of the moon does not influence when peak breeding of white-tailed deer occurs, because peak breeding is dependent on the climate. This suggests that peak breeding is triggered by the amount of sunlight, not moonlight. To help hunters determine when peak breeding occurs in their area I compiled the Rut Dates Chart, which gives both the breeding season length and peak breeding dates in most states where whitetails are found.
During my studies I did find a correlation between several different lunar factors, and peak monthly deer activity, and peak scraping activity. As a result of this I devised the Moon Indicator, which predicts which days hunters are most likely to see deer each month; when scraping activity is most likely to peak each month; and when hunters are most likely to see daytime breeding activity during the rut.
My studies, and the studies of several other researchers, clearly show that weather is one of the primary influences on daily deer activity, and that when it's too hot, too cold, too windy or too wet, the deer probably won't do what they would normally do. After four years of studying how the weather affects daily deer activity I devised the Daily Deer Movement Indicator, which predicts the best times and places to hunt deer each day based on the weather conditions that day.
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