T.R's Tips: Whitetail Breeding Behavior Factors
By T.R. Michels, TrinityMountain Outdoors
Deer are greatly influenced by the drive to breed in the fall. In some instances, especially with dominant breeding bucks, the breeding urge can override all other factors. Breeding Factors are one of the most powerful influences on fall deer movement and the change from summer to fall activity.
The Rut
Most hunters know that deer act differently during the rut, but after spending time with and talking to a number of different hunters, most of them experienced and some of them quite
knowledgeable, I realized many of them did not understand the progression of the rut. Most of them knew that rubbing in northern regions usually begins in September, scraping in October and the "peak of the
rut" occurs in mid- November. I don't know how they interpreted the phrase "peak of the rut". Did they think all the breeding activity would occur that one week? Many seemed to think that once the
peak had passed no more breeding activity would occur. They resigned themselves to the thought that if they did not get a buck by the "peak" there was no reason to hunt as hard as they had because there
was less activity.
Well hold on, I'm going to try to explain the rut and make it clearer. At the same time I am l hoping you will hunt harder in your quest for a big buck. Then again maybe not, if you don't
hunt hard it leaves me with more deer. First, let's examine the phrase "peak of the rut." Actually this term refers to the peak, on a curve, of the rut related activity. This activity includes rubbing,
scraping and breeding. Each of these activities has it's own curve.
Rubbing and Scraping
In the upper Midwest bucks often begin rubbing in early September. Peak rubbing activity usually occurs between mid and late September and generally decreases once the bucks begin scraping.
But, rubbing often continues as long as there are does in estrus, which may be as late as the end of December in the northern states. Scraping activity may start shortly after rubbing begins, but without much
activity until the rubbing activity peaks in September. Scrape activity often ceases when nighttime temperatures rise above 45 and this may be the reason for little scraping activity in September. As the nights get
colder in October scraping activity begins to rise, and usually peaks in late October or early November, just before breeding peaks. Breeding activity increases along with the scraping activity in mid-October, with
peak breeding occurring shortly after peak scraping in November. But what was that about breeding activity starting in mid- October?
Breeding
My own observations, those of noted wildlife photographer Bill Kinney and the studies of Dr. Larry
Marchinton and his colleagues in Georgia all show that does have been observed breeding 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. Thanks to Marchinton's study we can actually pinpoint estrus cycles in deer. The study was conducted to determine how many estrus cycles unbred does would experience. In the eight
does observed recurrent estrus ranged from 2 to 7 times, with the first estrus on October 17 and the last on April 7. This shows that if does go unbred hunters can expect a second "breeding period" in
December, after the "peak of the rut." The study also shows that there is a much longer "breeding period" than many hunters realize. I will use the term "breeding period" from now on
when referring to the actual time frame when does are receptive and when breeding occurs. It clearly states the time frame hunters are interested in when they refer to the "peak of the rut."
In Marchinton's study there were five 1.5 year old does, two 2.5 year olds, and one 5.5 year old. This is fairly representative of does in the wild and closely resembles the ages of the herd
I watch on a daily basis. One 2.5 year old came into estrus October 17, another 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 21 and the 5.5 year
old on December 1. This shows that the first estrus of a doe could occur anywhere from a month before the peak of the breeding period to almost a month after. Not all of the does came into estrus during the peak of
the breeding period, which would have been November 9th. In fact, not a single doe was in estrus on that date. There was a doe in estrus on November 10th and three on the 11th. Less than half the does were in estrus
the week of the peak of the breeding period. There were two does in estrus three to four weeks earlier and two does in estrus one week later. If recurrent estrus cycles are considered then there could have been
three does in estrus the first week of December, two the second week, two the third and one the fourth. This is a fairly typical pattern that causes the breeding period in many areas to last 90 days or more, from
mid-October to mid-December. Marchinton noted a breeding period of 96 days in South Carolina, that presumably lasted into January. The chances are most of the does in Marchinton's study would have been bred during
their first estrus. A significant second "breeding period" could and often does occur in many deer populations.
As a result of Marchinton's study we know we cannot reliably predict when the second breeding period will occur. Even if the majority of the does come into estrus at the same time the
research shows that recurrent estrus cycles are quite variable. Instead of occurring every 28 days as previously thought the cycles ranged from 21 to 30 days. This would make it difficult to pinpoint the second
breeding period, especially when coupled with the knowledge that the first estrus may occur anywhere from mid-October to the first part of December. Another note of interest is that the does were in estrus from 24
to over 48 hours, not the 22 to 24 hours previously thought.
Moon Phase and The Rut
Some researchers and writers believe that the rut will occur during certain moon phases. But, there is no conclusive evidence that the moon phase does affect the rut of white-tailed deer.
Although some of the does may be in estrus within a few days of one of one of the moon phases it does not mean all of them will be in estrus during any one phase. Even if moon phase affects the first estrus cycle of
a doe it may not affect subsequent estrus cycles, because not all does have the same length of estrus. We know that the estrus cycles of individual deer do not occur every 28 days, but every 21-30 days. However, the
moon phase does change every 29 days. Therefore, even if the first estrus of a doe fell on a certain moon phase the second estrus could be as much as a week before the next similar phase and two weeks before the
following phase.
Buck To Doe Ratio
When the local deer population does not have equal numbers of bucks and does, and most hunted deer populations do not, it can cause the rut to be out of synchronization. When there are not
enough bucks to leave priming pheromones for does to come in contact with, not all of the does will come into estrus or be bred during their first estrus. This will also cause some of the does to breed later than
normal.
Buck Movement
Not all deer react in the same way during the rut, which makes it difficult to determine the peak of the rut. Does respond differently than bucks, and older breeding bucks respond differently
than younger bucks. My research shows that during the rut, the movements of both subdominant and dominant bucks change as rut activity changes, but they do not change in the same way. During the study the dominant
bucks were sighted more frequently than the subdominants in the morning during both October and December. Morning sightings of dominants increased only slightly in November (during the peak breeding period) and
equaled about half the subdominant buck sightings, which increased dramatically. Young bucks during the rut act much like teenagers, they let their hormones control them and they do stupid things, like search for
does during daylight hours. Older bucks, however, have learned that in order to survive they need to be wary and travel during darkness.
The subdominant bucks were seen more often in the evening than they were in the morning during October. But, in November, during the rut, they were seen only half as often in the
evening as they were in the morning. In December they were seen more often during the evenings than they were in the mornings. This decrease in subdominant buck evening movement during the breeding period could be
attributed to the fact that dominant bucks are quite aggressive during the rut and the subdominants avoided the dominants. There were twice as many dominant buck sightings in the evenings during October and December
as there were morning sightings. However, during the November breeding period, while hunting pressure was the highest, the dominants were seen about the same number of times during the evening as they were in the
morning. Both dominant and subdominant buck sightings were greater in the morning than in the evening during November, possibly because they were late returning to their bedding areas after chasing or searching for
does.
Dominant and Subdominant Buck Movement Differences
Not only did dominant and subdominant bucks react differently to the progression of the rut they moved at different times than the does. During the morning in October the subdominant bucks
were seen about a half-hour before the does, while the dominants were seen at the same time as the does. During the evening in October the subdominants were seen at about the same time as the does, while the
dominants were seen about three-quarters of an hour later than the does.
During the mornings in November the subdominant bucks were seen a half-hour after the does, while the dominants were seen a quarter hour after the does. During the evenings in November the
subdominants were seen a quarter-hour before the does, while the dominants were seen at the same time as the does. It appears that the dominants began to move more closely to the time of the doe movement during the
breeding period.
After the primary breeding period in November but before the second breeding period in December neither the dominant nor subdominant bucks were seen outside the general area of their bedding
sites.
During the second breeding period the dominants were seen at about the same time as the does during both the morning and evening, while the subdominants were seldom seen in areas frequented
by the does.
During late December, after breeding activity ceased, the dominants were seen from about the same time as the does to about an hour and a half after the does. This probably occurred because
the bucks were searching for food in order to gain back the weight they lost during the rut, which would help them get through the winter. The subdominants were seldom seen at the same time as the does or in areas
frequented by the does.
This data confirms what many hunters have believed for years. Older, dominant bucks are "smarter" than young bucks and does. They also react differently to the rut than younger
bucks, and they move at different times and in different places than most other deer. But, they often throw caution to the wind and can be taken by the persistent hunter when the rut is on, and during late winter
when food sources are scarce.
If you are interested in more whitetail hunting tips, or more whitetail biology and behavior, click on Trinity Mountain Outdoor News and T.R.'s Hunting Tips at www.TRMichels.com. If you have questions
about whitetails log on to the T.R.'s Tips message board. To find out when the rut begins, peaks and ends in your area click on Whitetail Rut Dates Chart.
This article is an excerpt from the Whitetail Addict's Manual ($19.95 + $5.00 S&H), by T.R. Michels.
T.R. Michels is a nationally recognized game researcher/wildlife behaviorist, outdoor writer and speaker. He is the author of the Whitetail, Elk, Duck & Goose, and Turkey Addict's Manuals. His
latest products are the 2003 Revised Edition of the Whitetail Addict's Manual, the 2003 Revised Edition of the Elk Addict's Manual; and the 2003 Revised Edition of the Duck & Goose Addict's
Manual. For a catalog of books and other hunting products contact: T.R. Michels, Trinity Mountain Outdoors, PO Box 284, Wanamingo, MN55983, USA. Phone: 507-824-3296, E-mail: TRMichels@yahoo.com , Internet Site: www.TRMichels.com
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