If you can identify any of these six factors in the deer of your area, chances are you’ll experience a prolonged rut.
According to former University of Mississippi professor Harry Jacobson, some late-breeding (or lack thereof) appears to be genetically linked and not easily altered.
In Mississippi, for example, deer normally don’t start breeding until November. Even when Jacobson transported Michigan deer to Mississippi, the Northern subspecies maintained its October and November breeding dates. Meanwhile, Mississippi does continued to breed in late December and January when moved to Michigan. Crossbred offspring of Michigan and Mississippi deer bred over the entire range of both parents.
2. Abundant Nutrition
On Northern range, no single factor is likely more influential than nutrition in determining a doe’s rate of sexual maturity and the timing of her breeding. Interestingly, both excellent and poor nutrition might account for some late-breeding and a prolonged rut.
3. Nutritional Shortage
Inadequate nutrition invariably leads to delayed sexual maturity, limited breeding among doe fawns, and a high incidence of barren yearlings, as well as low productivity and slightly delayed estrus onset among mature does.
4. Density Stress
Based upon the breeding records of more than 500 supplementally-fed does, most (70 percent) does 3½ years of age and older raised in the square-mile Cusino enclosure bred between Nov. 8 and Nov. 23, annually. Ninety-four percent of them bred during November. They maintained this strict breeding schedule regardless of herd density or buck age structure — even with more than four does per buck, or when all bucks were of yearling age. Only 4 percent bred during December or later.
5. Maternal Domination
Later studies suggested late breeding among young does was due to behavioral subordination that caused certain hormonal imbalances leading to their delayed onset of estrus.
For example, we found significant differences when we compared the breeding dates of 2½-year-old does that successfully raised fawns versus those of the same age that did not raise fawns.
Buck-doe interactions or excitation (i.e., biostimulation), or lack thereof, might also be important in determining the time of doe breeding. Studies with penned deer at Cusino, for example, showed that unnatural confinement of does with a rutting buck advanced average breeding dates by as much as 10 days.