Predicting Peak Rut Activity & Days to Hunt Deer
- Blog Post by: T.R. Michels
- October 14, 2012 - 6:36 PM
Sorry I have not been around, my daughter and I have both had fairly severe medical problems we have had to deal with. We are better, but we are not out of the woods yet, so prayers are appreciated.
Predicting the Rut & Best Hunting Days
Whitetail hunters often want to know when the "peak of the rut” occurs. Unfortunately the term "peak of the rut" appears to mean different things to different people. To a deer biologist it means the one week of the breeding season when more breeding occurs than during any other week. Note, I said "more breeding". I did not say "peak stupid buck activity", "peak buck sightings" or "peak sightings of bucks trailing, chasing, or breeding does", or "peak sparring or fighting"; all of which some hunters mean when they say or think "peak rut".
PEAK RUT means the ONE WEEK of the year when more breeding occurs than in any other week.
Since all of the other activities hunters may refer to when they think or speak about "peak rut" are affected by the number of deer in each area, the buck to doe makeup of the herd, the age structure of the herd, the health of the deer, the weather, possibly the moon, and certainly the amount and whereabouts of food in the area, it is extremely difficult to state when those activities will occur. However, it is possible to predict when "peak breeding" should occur, because the biologists in many states have done studies to determine when peak breeding occurs.
In 1985 Dr. Larry Marchinton conducted a study to determine how many estrus cycles unbred whitetail does in Georgia would experience. Of the eight does in the study one 2.5 year old came into estrus October 17, one 2.5 year old on October 24, three 1.5 year olds on November 11, one 2.5 year old on November 19, one 1.5 year old on November 22, and one 5.5 year old on December 1. Recurrent estrus ranged from 2 to 7 times. This shows that some does may come into estrus in October, most in November, and some in December. In northern areas 1.5 year old does usually come into their first estrus in December.
During another study Marchinton noted a total breeding period of 96 days in Georgia, which presumably lasted into December. Because of this extended breeding period I use the term "breeding period" when referring to the total time frame when breeding occurs. I use the term "primary breeding phase" in reference to the week when most breeding occurs, because it more clearly states the time frame hunters are interested in when they refer to "peak of the rut." In Canada and most Northern states this primary breeding phase occurs in November, shortly after peak scraping.
Marchinton's research in Georgia, my own studies here studies here, and the observations of others, show that does have been bred as early as September 24 near the Canadian border in Minnesota, October 15 in southern Minnesota, October 17 in Georgia and October 24 in central Wisconsin. In much of North America breeding may occur as early as mid-October, with the “primary breeding phase” from early to late November, and a late breeding phase in December.
During his Georgia research Marchinton found that the estrus cycles of whitetail are quite variable. Instead of occurring every 28 days as previously thought, the estrus cycles of the does in the study ranged from 21 to 30 days. This makes it difficult to pinpoint the timing of the late breeding phase, especially when coupled with the knowledge that the first estrus of a doe may occur from mid-October to the first part of December. Marchinton also noted that the does were in estrus from 24 to over 48 hours, not the 24 hours previously thought.
My studies in Minnesota show that roughly 10-20 percent of the does come into estrus during the early breeding phase (approximately October 15 - September 7 in the upper Midwest), 50-60 percent during the primary breeding phase (approximately September 8 - 28 in the upper Midwest), and 20-30 percent during the late breeding phase (approximately December 1-21 in the upper Midwest).
It made no difference if I considered the estrus dates of the does from October through December, or only the estrus dates in November, the peak of the rut occurred within seven days of November 10. The primary breeding phase usually lasted three weeks, from approximately November 1 to 21.
Photoperiod and Other Influences
The breeding phase for deer in each area is predominantly triggered by the number of hours of sunlight each day (photoperiod). Since whitetails inhabit a large portion of North and Central America, and a small portion of northern South America, the geographic location of individual deer herds determines when breeding should occur. The rut is governed by the timing of spring. In order for fawns to survive deer need: 1. weather warm enough that the fawns won't die of exposure, and 2. weather that is wet and sunny enough to produce new forage, so the does can produce milk for the fawns. Deer in the north have short breeding periods because they have a late spring and early fall, resulting in short summers. Deer in the south do not have to breed as early, and have longer breeding periods because of the long summers and late fall. Whitetails in the southern United States may have up to a five month breeding period (September-January). Deer above the 40th parallel generally breed when there are approximately 10 hours of sunlight per day, which occurs in early November.
Robert McDowell completed an interesting study called Photoperiodism among breeding eastern white-tailed deer in 1970. This study documented the breeding dates of whitetails from the 28th parallel to the 48th parallel. The dates given covered a broad range because the study encompasses the entire eastern half of the United States, from approximately the Rocky Mountain foothills east, and from the northern range of whitetails in Canada, to the Mexican border. Obviously, the breeding dates in each area varied due to the local weather conditions, and the genetics of the herd.
According to the results of the study - for deer below the 28th parallel, breeding may occur from the first week of August through the last week of February; with peaks in breeding activity occurring from the first week of September through the second week of October, from the third week of November through the first week of December, and from the second week of January through the first week of February.
For deer between the 28th and 32nd parallel breeding dates were from the second week of September through the first week of February, with peak breeding from the first week of November through the first week of February.
For deer between the 32nd and 36th parallel breeding dates were from the first week of October through the first week of January, with peak breeding from the first to the fourth weeks of November.
For deer between the 36th and 40th parallel breeding dates were from the second week of October through the last week of January, with peak breeding from the first to the third week of November.
For deer between the 40th and 44th parallel (includes Minnesota) breeding dates were from the first week of October through the last week of January, with peak breeding from the last week of October to the second week of November.
For deer between the 44th and 48th parallel breeding dates were from the last week of September through the last week of November, with peak breeding from the first week of November through the first week of December.
Several factors besides latitude and photoperiod may cause fluctuations in the rut. When local deer populations are not balanced properly (most are not), the timing of the rut may be affected. If there are not enough mature bucks to leave priming pheromones at rubs and scrapes for the does to come in contact with, some of the does will not come into estrus, or be bred, during the normal breeding period, causing them to breed later than normal. The amount of forage in the habitat (which may be affected by local weather conditions), and the health of the deer (affected by amount of forage, disease and population density), also affect the timing of the rut. Undernourished and unhealthy does may come into a first estrus a month or more after other does.
Genetics can play a large part in when deer breed, as shown from a study in Louisiana. In 1983 researchers found that deer in the Camp Avondale Boy Scout Reservation in East Feliciana Parish bred from November 6-26, with a median date of November 12, a full month earlier than the deer for the rest of the parish. The reason for this earlier breeding is because the deer in the camp were relocated from a herd in the Red Dirt Management Game Management Unit, where breeding occurs earlier.
Several writers and biologists have suggested that peak breeding is influenced by the phase of the moon. Their theories may be based in part on the belief that a combination of shortening photoperiod (number of light hours per day) combined with melatonin production (which may be affected by moonlight) will cause does to come into estrus shortly after the full moon in November.
Interestingly, during Marchinton's 1985 study the full moon occurred on October 28 and again on November 27, with peak estrus occurring November 9, showing no correlation with the full moon. This lack of a correlation between moon phase and peak rut was to be expected because of the lateness of the November full moon. I suspect that when the full moon occurs too early or too late - the rut will occur when it usually does, during mid-November in the many areas.
Marchinton's research shows that not all does come into estrus during a particular moon phase, and that they may not even come into estrus during the same month; which shows that the phase of the moon does not affect when peak breeding occurs. This is supported by the findings of the Minnesota Department of Natural Resources, and an exhaustive study by Dr. Karl Miller and others, which looked at the breeding dates of about 2500 does from 10 states, ranging from the southeast to the northeast, and from Minnesota to Texas. Their study concluded that there was no correlation between peak breeding of white-tailed deer and any moon phase. This means that the best scientific evidence available shows that the phase of the moon does not affect when deer will breed, or when peak breeding occurs.
Moon Position, Gravity, Biomagnetics
My personal studies, research by Kent Kammermeyer, and research by Grant Woods, suggest that there is a correlation between increased daytime deer activity and the moon. These correlation's are related to the position of the moon and the earth; the distance of the moon from the earth; the position and speed of the moon in its elliptical orbit; and combinations of these factors. The position of the moon (not the amount of light) during the full moon phase) may cause increased gravitational pull, and the distance and acceleration of the moon during the perigee (when it is closest to the earth in it's elliptical orbit) may cause changes in the magnetics of the earth. The independent or combined effects of these two factors appear to increase daytime deer activity.
Because the elliptical orbit of the moon (the time it takes the moon to revolve around the earth) has a 27 1/2 day cycle, and the light phase of the moon has a 29 1/2 day cycle, the full moon and the perigee can occur on the same day, or as much as two weeks apart. This difference in cycle lengths may be the reason why deer movement is high during the full moon in some years but not in others. I suspect that when the full moon and the perigee occur at about the same time (as in 1997) there may be increased daytime movement of deer.
No one really knows if and how these lunar factors affect deer activity; which lunar factors influence deer activity and how much, or what happens when the perigee and the full moon occur two weeks apart. The key thing to remember is that daytime deer movement (including during the rut) appears to be highest during the week of the full moon each month.
However, hunting pressure, the rut, food availability and the weather can completely override any affect the moon has on deer. My studies show that during November, when both the hunting season and rut are in progress, there was no noticeable peak in daytime deer activity. For more information on how the moon affects the rut refer to the Deer Addict’s Manual, Volume 4:
Lunar Factors, The Real Truth.
Because the perigee/apogee and full moon occur at different times during November this year here is my best "guestimate" as to when the moon may cause increased deer activity during November; from about October 25 to November 1 (this may be the end of peak scraping activity and the beginning of peak breeding activity in the upper Midwest) and from about November 25 (this may be about the middle to the end of peak breeding activity in the upper Midwest) to December 1.
As a result of increased monthly gravitational pull of the moon Peak “daytime buck sightings” may occur the week before the dates given above, as the bucks look for does coming into their first estrus. Daytime buck activity should be greatest when there is a visible full moon at night (which may cause the deer to become nervous, because they may be seen by predators). You may also see bucks during the day from November 8-14 (when the moon is closest to the earth) which is when an increase in the biomagnetics between the sun and the earth may cause increases in melatonin levels of the deer, resulting in a corresponding increase in the “ mood” of bucks, and them continuing to look for unbred does.
The dates given are when it may be most likely to see increased rutting activity during “daylight” hours. Since 30-50+ percent of the does may be bred during the early November dates, 1-21, which means the bucks may be looking for does unbred does throughout the day. This is especially likely if there is cloud cover during the day, the temperatures are below 40 degrees, the wind speed is below 10-15 miles per hour, and there is little to no precipitation. If those conditions occur where you hunt, you can hunt from dawn to dusk, because you may see bucks at all hours of the day.
In fact, no matter what is going on – if those conditions exist – get out and hunt, because those are optimal conditions for daytime deer (including trophy buck) movement. For archery hunters, hunt the days 30 days prior to the dates given for the gun season.
To find out when the rut generally starts and ends and when "peak breeding" occurs in your state log on to www.TRMichels.com, then click on Peak Whitetail Rut Dates Chart.
If you are interested in more whitetail deer hunting tips, or more whitetail biology and behavior, click on Trinity Mountain Outdoors Magazine and T.R.'s Hunting Tips at www.TRMichels.com. If you have questions about hunting log on to the T.R.'s Hunting Tips message board.
This article is an excerpt from the Complete Whitetail Addict's Manual ($40 + $5.00 S&H for soft cover book; $20 for e-mail copies), by T.R. Michels, available in the Trinity Mountain Outdoor Products catalog at www.TRMichels.com.
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