Ready for the Rut: How Whitetail Bucks Change as Fall Heats Up

Photos by Charles Alsheimer

Bucks are about to undergo a change like none other in the animal world. If you blink, you might miss it.

September is a magical time in the whitetail’s world, but things change rapidly as the month gives way to October. This is the time of the year bucks’ personalities rapidly change, and they become much less cautious. It was amazing to witness because mature bucks will go from being calm, cool and collected to off-the-wall stupid at certain times.

Every buck is different. Their level of foolishness has much to do with their personality and the situation in which they place themselves.

A white-tailed doe walks through autumn woods with a mature buck following behind her. — *As the breeding phase approaches, bucks spend more time on the move searching for and pursuing does. Photo by Charles Alsheimer.*

When Rut Behavior Takes Over

By the time November and the breeding phase of the rut is about to explode, bucks are on the prowl all hours of the day. They sleep very little, and their food intake drops off drastically. They pick a fight with nearly every buck they encounter and aggressively pursue does.

In short, they are totally different deer than they had been when September gave way to October.

The Hormonal Shift Behind the Rut

One of the first studies dealing with hormonal changes in white-tailed bucks was conducted in 1972 by Lambiase, Amann and Lindsey. Using captive and wild white-tailed bucks, these scientists investigated the reproductive physiology of bucks from Pennsylvania.

They determined a white-tailed buck’s sperm output peaks in mid-November. They also discovered the testicular weight and sperm concentration were greater in older bucks than yearlings, and the bucks had enough sperm for adequate breeding from October through February.

These findings helped to reveal why white-tailed bucks are different creatures from mid-October through mid-December.

Testosterone Changes More Than Behavior

After a buck peels velvet in late August to early September in the North, its testosterone level begins to rise. Testosterone levels peak around the beginning of November, and by the end of December the levels are nearly back to what they were in September.

This increase in testosterone and other hormones has much to do with the physical characteristics of bucks during the autumn months. Once velvet peel has taken place, a buck’s muscle definition becomes increasingly pronounced as September inches its way to November.

By the time November and the rut has arrived, a dominant buck resembles a body builder. He is also in a hormone fog, which keeps him from thinking clearly.

Two white-tailed bucks spar and lock antlers during the fall rut. — *As testosterone rises, aggression between bucks increases and encounters can quickly turn into fights. Photo by Charles Alsheimer.*

Out of Control

Flooded with hormones, a buck’s scraping and rubbing behavior ramps up in October and peaks in November.

Bucks are so focused on breeding they throw all caution to the wind. Rather than moving at night, they move around whenever they feel the urge. Rather than staying away from aggressive bucks, they go out of their way to pick fights with them. Rather than conserve energy and feed, they run themselves into the ground.

In short, they are so juiced on hormones they turn into raging maniacs.

Buck behavior from mid-October to the end of November not only wears a whitetail down but greatly increases his chances of dying from an arrow or bullet. It is certainly interesting to observe, but it is also helpful to hunters.