Hunters and drivers get ready: peak of the rut is just days away

The most anticipated part of deer hunting season — the height of deer breeding known as the rut — is just a few days off.

Nature’s dance between bucks and does reaches its zenith Nov. 10-20, said state deer biologist Paul Shelton.

That’s when a buck’s testosterone levels are surging and his preoccupation with the opposite sex means he’s probably paying less attention to his surroundings.

That could include a bow hunter in a tree stand nearby or a car traveling down the road.

Shelton, forest wildlife program manager for the Illinois Department of Natural Resources, says that when deer-vehicle accidents are plotted day by day, the number tops out at the same time as the rut.

Motorists may not think of themselves this way, but cars and trucks are the other major predator of the white-tailed deer in Illinois.

The process plays out over several months, starting in September.

“The rut is one long drawn-out process that goes through different physical and behavioral changes,” Shelton says. “Everything starts in early September with antlers hardening and bucks start shedding velvet.”

Velvet is the stage before the antler begins to calcify.

As the process begins, testosterone levels start to rise, triggered by decreasing hours of daylight.

Then deer start sparring by pushing each other.

“It serves as a test of strength and helps establish a buck’s rank within the herd,” Shelton says. “Are you number one? Number 2? Or are you way down the list?”

Rubbing behavior is next. Bucks may rub small trees or shrubs, mostly as a form of exercise — strengthening muscles.

“Deer find a location like an over-hanging branches that they chew,” he says. “Or they make a scrape on bare ground, marking the spot with urine.”

The spots where deer rub or scrape become chemical signposts, Shelton says.

“They leave a sign that they have been there,” Shelton says. “I think deer understand the signs better than people do.”

As the peak draws closer, Shelton says breeding activity peaks in the familiar bell-shaped curve. Activity gradually increases, comes over the top of the curve and then gradually declines.

“Bucks tend to be reproductively ready before does come into estrus,” he says. “They may be actively seeking does that are ready to breed, but right now few does have come into estrus yet.”

Hunters can attract bucks ready for breeding by rattling antlers together, simulating a dispute between rivals.

“Rattling can be productive, because bucks are looking to get in on any action.”

Shelton says peak breeding times can be predicted by looking at the time when fawns are being born and backtracking 200 days — the length of gestation.

Fawns born in late May and early June can be traced back to the mid- to late November breeding season.

“That’s not to say there are not deer breeding now — there are,” he says. “But right now we are on the upward slope of the curve heading towards the peak of the rut.”

The bell curve may not be perfectly smooth.

Shelton says the majority of does are bred during this cycle, but that some that may have been missed come into heat again 28 days later.

“A lot of hunters refer to this as the secondary rut,” he says. “It tends to pale in comparison to the first one.”

Rutting activity can continue later because young fawns are not sexually mature in time. Those young does will not be bred until later in the season, if at all.

Eventually, testosterone levels in bucks start to fall — and so do those prized antlers.

“It all ends at antler shed,” Shelton says.

Some bucks lose their antlers as soon as mid-January.

Others hang onto theirs through February and even into March.

Then, it’s time for nature’s cycle to begin anew, Shelton says.
“Then they’re ready to start the whole thing again.”