Sorting out the whitetail rut: Timing is everything

Sorting out the whitetail rut

As the whitetail rut is experiencing its first peak here in the Northeast and Midwest, in early November, questions arise.

It is a fact that whitetails around the country experience different Rut timing.

Why is that?

Whitetails in New York, and throughout the Midwest, rut, or breed, in October and November for the most part.

But in Mississippi the rut peaks from late December to late January.

Why such a difference between the North and the South?

We haven’t seen such a contrast since the Civil War.

I think the best way to imagine how the rut unfolds in time is as a statistical bell curve by region.

Deer in northern latitudes have a smaller and less forgiving window, while the further south one travels, the climate for fawn survival is more forgiving.

Sure, some deer break the mold and breed very early, and a few will breed months later than the average.

But the peak of the rut is really theoretical … as that date when more doe are bred than on any other date in a given region.

And we have determined that peak rut date through the observation of whitetail rutting behavior.

Confusions begin with the definition of the rut.

There are early signs of the impending rut, such as intense scrape making by bucks, and the daytime running of bucks.

Some say when we see those spikes of action in the woods, "the rut is on."

Chasing of doe is observed. But the real rut, the actual breeding, always follows the running time of the bucks by at least a few days.

And we note as a further indicator that "the scrapes go dead."

What adds a confusing dimension to the rut timing models is when we consider southern portions of the country.

Evidently, according to researchers, different strains of whitetails create their own unique rut dates and timing specific to that region.

For instance, Michigan deer have been taken down south and shown to keep their northern rut timing.

Various Rut timing systems have evolved, giving hunters the opportunity to drill down to a two- or three-week peak period in their hunting area.

Each of the belief systems or rut methodologies has their own fervent apostles and equally passionate detractors.

Fetal measuring studies, which many game departments genuflect in front of, posit the notion that deer breed at the same time on the calendar each year.

Fetal studies are based on a scientific methodology that measures the size of deer fetuses.

The length of the fetus is then measured against a growth rate scale.

The measurement of many fetuses, usually from road-killed doe, is repeated over and over until a statistically significant base is reached.

But accuracy problems arise and have been chronicled, especially in the origin and calibration of the base fetal measuring scale.

Doe are expensive to raise and breed.

The determination of the exact conception time of any given fetus can be problematical.

But at any rate, in order to make an accurate baseline fetal scale, pregnant doe must be sacrificed, the fetus extracted and measured.

Repeating this process over and over along the 200-day gestation period produces the scale.

But how accurate are these scales?

One would expect that there would be a close correlation in the measurements between two (or more) studies that produce fetal scales.

The statistical base of the most popular fetal studies (there are about five) is lower than expected. (Only 17 doe were used in one study (Cheatum-Morton) to 76 doe in another (Armstrong).

More:How to take advantage of buck scrapes when hunting, or simply getting photos of deer

Questions arise when we find that the major fetal studies lack correlation and agreement in the measurements-to-age ratio. But really not that surprising taking into consideration differing factors in size of individuals, reflecting differences in age, health, range, DNA, strain and climate effects, to name a few.

For instance: A 100-millimeter fetus in the Cheatum-Morton study is 54 days old. A 100 mm fetus in the Armstrong study is 67 days old. A 100 mm fetus in the Short study is 79 days old and that same 100 mm fetus is 69 days old in the Hamilton et. al. study. If the studies (scales) don't correlate, then why are they used at all?

The physical process of measuring a crown-to-rump fetus has variables from the ability and technique of the human technicians (measurers) on the one hand and the non-constant growth curve, on the other to adapt a useable linear, two-dimensional scale as a base.

And beyond those questions ... think about it.

Human infants differ in size, as do fetuses of dogs, cats, chickens and deer.

And with these relatively new DNA whitetail studies, according to studies published in the Journal of Mammology, 26% of whitetail fetuses have multiple paternity (different fathers).

Someday in a future deer season, whitetail hunters will be on the same page when discussions of rut timing take center stage around the fire.

But it is not now.

— Oak Duke writes a weekly column.