Buckmasters Magazine

Rut Factors

Rut Factors

By David Hart

It’s the best time to tag a monster buck, so why aren’t you seeing any?

It’s the peak of the rut, so it’s only natural to expect a giant buck to chase a doe past your stand. Isn’t that what’s supposed to happen during the rut?

But after a full day in the woods, you see nothing but a disinterested spike and a few bored-looking does. You wonder: Was the rut early this year? Did it get delayed by a warm spell?


Although peak rut dates vary from region to region, state to state and even within some states, they all have one thing in common: They take place on nearly the exact same dates, year after year. You can set your clock by the rut calendars put out by some state wildlife agencies. They are that precise.

Thanks in part to the work of Quality Deer Management Association founder and former South Carolina DNR wildlife biologist Joe Hamilton, biologists can calculate the precise rut dates for any region.

Hamilton devised what biologists call a fetal tape, a highly accurate tool used to determine the age of a fetus. In fact, the method used by biologists everywhere is often called the Hamilton method. It relies on nothing more than a tape measure that determines the rump-to-forehead length of a fetus.

Since they all grow at about the same rate, fetuses that measure a specific length are all the same age. With that knowledge, biologists can then tell how old a fetus is. They also can calculate the conception date by counting backwards.

If, for instance, a doe was killed on Dec. 30 and the fetus is 45 days old, it was conceived on Nov. 15. Using that, biologists can compile a baseline of data that shows when most fawns were conceived. That average date is the peak breeding period.

“In Virginia, it’s always a roughly 10-day window that takes place in mid-November,” says Virginia Department of Game and Inland Fisheries deer project coordinator Matt Knox. “The specific dates vary somewhat by region, but no matter where you are, the peak breeding season takes place at just about the same time every year. We know that because we’ve gathered enough data over the years using fetal measurements.”


The peak breeding takes place at specific times for a single, simple reason: evolution. Whitetails have evolved over tens of thousands of years to have their fawns when it ensures the highest chance of survival.

Northern states have a shorter growing season and an earlier winter. Since fawns are more vulnerable to extreme cold weather typical of New England and the upper Midwest, they need to be born by a certain date in order to grow large enough and healthy enough to survive.

A fawn born late has a considerably lower chance of survival. That’s why breeding activity we associate with the rut takes place during a short window, sometimes as little as seven days in northern states.

Whitetails farther south, however, are rarely subjected to severe weather, so the rut can take place over a longer period. But even in places like Virginia, the peak rut tends to take place within a two-week window. That’s not to say all the does are bred inside that window, but the vast majority are, according to Knox.


Scientific data isn’t enough to convince everyone. Lots of hardcore deer hunters swear the timing of the rut is heavily influenced by weather. Mississippi DNR wildlife bureau assistant chief Chad Dacus says the weather does influence rut activity, but it doesn’t change the timing of the peak breeding season. It simply alters the behavior of bucks.

“I often hear the rut doesn’t get started in Mississippi until the first cold snap in December,” he says. “Our data shows the peak breeding dates are the same, no matter what the weather.”

Knox agrees, adding that warm weather simply forces whitetails to shift their breeding behavior. There’s a difference between breeding behavior and breeding activity.

“You wouldn’t want to run all over the place in a fur coat if it was hot out, would you?” Knox asked. “The does are getting bred, but most of the activity is taking place at night when it’s cooler. Bucks are less likely to chase does when it’s abnormally warm.”

Even in colder or more seasonal weather, much of the rutting activity we hope to see takes place at night. One study in Maryland’s Eastern Shore found that GPS-collared bucks spent most of their time either bedded down or deep within thick cover in daylight hours during the peak breeding season. They rarely ventured into the open. The study took place on a lightly hunted 3,000-acre farm.

Rut FactorsThe moon did not alter peak breeding times, either. Numerous studies have examined lunar cycles and whitetail activity in general, and breeding activity in particular. None have found any correlation.

Quality Deer Management Association director of outreach and education Kip Adams says it all comes back to scads of data collected by biologists that indicate a brief, defined breeding period throughout much of whitetail country.


That’s not to say other factors don’t influence rutting behavior. The buck-to-doe ratio plays a considerable role. Biologists once thought bucks in their prime – 3 1/2 to 6 1/2 years old – bred the majority of does. Extensive research has found that not to be true. Bucks of all ages will breed does.

That phenomenon is more pronounced in regions with more does than bucks. With too many does, bucks simply don’t have to chase or cover lots of ground in search of a receptive female.

“That’s one reason rattling works so well in places like South Texas,” Adams said. It’s not because the deer are any different. It mostly has to do with the fact that the ranches down there are heavily managed for buck-to-doe ratios and buck ages. There are fewer does, so bucks are more likely to fight for them.”

A higher percentage of older bucks in the population means they are more likely to cruise in search of a receptive doe and exhibit other behavior we associate with the rut.

Regions that have a low buck-to-doe ratio also tend to have a very low number of adult bucks, thanks largely to non-selective hunting pressure. Antlered deer get shot before they have a chance to age. Knox and Adams agree that hunters who fail to see adult bucks during the rut might not be seeing them because they just aren’t there.

In some regions of North Carolina, for example, there are less than 15 deer per square mile. Other regions have similarly low densities. Depending on hunting pressure, five of those may be antlered bucks, but only one might be a 3 1/2-year-old male.

With a home range of a square mile or more – even larger during the peak of the rut – that buck might never walk past your stand. You are likely to see more deer in areas with higher deer densities, but the number of adult bucks might not be sufficient to guarantee you’ll see one. It’s simply a matter of chance.

“The guys who are seeing several adult bucks in a single day are probably hunting in areas that are intensely managed,” Adams said. “Or they just happen to be in the right spot at the right time.”


It’s also true there are more mature bucks in areas that aren’t pounded by hordes of hunters.

That spike you saw was exhibiting the classic signs of a buck during the breeding season: a steady gait through open woods, stopping occasionally to test the wind. He might have even been trailing a doe, nose to the ground, oblivious to the dangers that lurked in the autumn woods. That’s one reason young bucks make up such a high percentage of the harvest. They are easier to kill.

“Think of yearling bucks as typical teenagers,” Adams said. “Research in Michigan found that young bucks spend a lot of time running around and chasing everything. They are far less likely to be cautious.”

Mature bucks will throw caution to the wind, too, but once they’ve been bumped around by hunters, they are far less likely to expose themselves to danger. We’ve all been told that bucks get stupid during the rut and will risk their lives to pass on their genes. Some do. However, that’s not necessarily typical, says Adams.

“If the area gets hunted a lot, bucks are much more likely to stay in heavy cover, even during the peak breeding season,” he said.

That means they might stop chasing a hot doe if she runs across open ground during daylight hours. Passing along their genes isn’t quite as important as surviving another day to breed.

It’s just one factor that plays into the big picture of breeding activity. Just because you aren’t seeing giant bucks running crazy through your woods doesn’t mean the rut isn’t in full swing.

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This article was published in the November 2013 edition of Buckmasters Whitetail Magazine. Subscribe today to have Buckmasters delivered to your home.

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