Outside Factors Affecting the Rut

The past two months we have talked about the two major predictable factors – daylength and moonlight – in the timing of the rut. A hunter can look ahead and predict how they may affect the timing and character of the rut. There are, however, other outside influences that can sway the timing of the rut, at least to minor degrees, and how the rut is played out. Some of these other factors can be identified in advance, such as hunting pressure and herd condition, and their effects anticipated. Others, like weather, are more short-term in nature and cannot be anticipated with any level of assurance. Yet, all of these factors figure into hunting strategies. 

As we look at these other factors, we’re going to be mostly concerned about their impact on the intensity of rutting activity and not actual breeding, though some, like herd condition, can affect breeding. In most cases, their effect on breeding is minimal, but what they do to rutting activity can be dramatic. They can give at least the appearance of delaying, pausing or outright stopping the rut. Thus, we need to look into them. 

Hunting Pressure

No other outside factor affects the nature of the rut as much as hunting pressure. Overall, the relationship between hunting pressure and rutting activity is simple: The higher the hunting pressure, the poorer the rutting activity. Excessive pressure brings both immediate liabilities and insidious long-term repercussions. Short term, heavy pressure drives the deer underground, so to speak, disrupting normal patterns, suppressing movement and wreaking the rutting ritual, the very thing hunters depend on to put a mature buck in their sights. Longer term, when excessive pressure is exerted year after year, there no longer remains any hope of a “normal” rut. The sex and age structures of the herd are so skewed that normal whitetail social behavior becomes a thing of years gone by, resulting in an indistinct, low intensity rut lacking visible rutting activity or its associated buck sign.

Temperature

Even when everything else is right, the wrong temperature can thwart rutting activity. What is the wrong temperature? Basically, anything above normal for that time of the year at that place stands to seriously curtail rutting activity. Why? It’s the temperature “comfort zone” concept. Deer move best when the temperature is the most comfortable and invigorating for them relative to what they are used to and prepared to face. In the fall, when deer are all “dressed up” for coming winter, relatively cool temperatures feel good to them and spark movement. On the other hand, relatively warm weather is oppressive and curtails activity. It is possible for the temperature to fall below the comfort zone and cut into rutting activity, but this seldom is a problem, at least for very long. I’ll take severe cold over major hot any day.

Few things can so severely suppress rutting activity like unseasonably warm weather, especially several days of it in succession. Throw in high humidity, and you might think about going fishing. During unseasonably warm, humid (we call it muggy) weather, daylight rutting activity all but ceases and the rut becomes largely a nocturnal affair. 

Because of the role cooler temperatures play in deer activity, weather systems, specifically cold fronts, figure prominently into the rutting picture. Cold fronts – normally accompanied by cooler temperatures (obviously), lower humidity and high barometric pressure, all things favorable for good deer movement – often trigger intense rutting activity. I’ve seen incredible turnarounds in rutting activity be swept in on the winds of a cold front many times, from Canada to Texas and Georgia to Montana. A recent Montana experience well illustrates the triggering effect of fronts. 

Several days into what should have been the rut, shirtsleeve weather persisted and I hadn’t found anything close to a shooter. I had tried nearly everything – rattling, grunting, aggressive still-hunts, stand-hunting clearcuts and scrapelines, hunting high and hunting low – but nothing seemed to work. Finally, the weatherman said a major cold front was rolling in, bringing with it several inches of snow and sub-zero temperatures. The mercury went from 60 above to 10 below overnight. After a short recoup time (about a day and a half) from the shockingly cold weather and snow, the big bucks came out of whatever hole they had been in. During the next six days, I was neck deep in big bucks. I shot a 155-point 10-pointer, watched my two hunting buddies from Georgia miss four 150-class bucks and guided both my wife and oldest daughter to bucks in the 130s! Yes, temperature can impact the timing and intensity of rutting activity! 

Often, cold fronts are followed by gusty, unsettled winds. When this happens, the best deer movement may delayed until the weather settles, which usually comes a day or two after the passage of the front. Also, when a front is accompanied by a substantial amount of snow, it has been my experience that deer movement doesn’t really crank up for a day or two following. Frequently, as fronts move in, they also bring with them something else that can greatly boost rutting activity – drizzle. 

Drizzle

Like cooler temperatures, a drizzling rain, or heavy mist, can trigger rutting activity, and as an added bonus, it makes deer less wary, even the jittery old bucks. Frankly, I don’t know of a better time to be in the woods than during a drizzly day when the rut is underway. This is especially so when several warm days precede the coming of a drizzling rain, as is often the case. For some reason, drizzle incites aggression in bucks and puts them on the hunt for does. I’ve seen an explosion of trailing and chasing activity come with drizzles. I also have had some remarkable rattling days during the rut thanks to drizzles. One particular drizzly morning in South Texas, 16 mature bucks answered my rattling horns. All of them were big, and several of them put on shows with brush-beating displays of their own. I’ve never sensed such aggression from whitetails as was exuded that morning. I rattled in four or five of them more than once. One came back a second time with a six-foot mesquite limb tangled in his antlers, causing momentary cessation of my heartbeat and visions of my name by the world record non-typical. Several of my best bucks have fallen on just such days. Drizzle can, however, wear out its welcome. If a drizzle persists more than a couple of days, deer activity rapidly drops off. They just seem to get tired of it. So do I.

Extremes In Weather

Extreme weather of almost any kind can put a damper on rutting activity. Needless to say, severe storms will bring proceedings to a halt. So will heavy rain. In heavy downpours, deer will hold up in thick cover and cease almost all activity. I’ve sneaked into evergreen thickets in driving rains and found deer standing, slightly hunched with their heads hung, looking miserable and forlorned. Once rain stops, business usually returns to normal, or better, soon thereafter. I really like to be in the woods right after a lengthy heavy rain. The deer seem to revel in the relief and are anxious to catch up on the rutting festivities. 

A heavy snowfall will also drive deer into a holding pattern. Unlike rain, however, its effect may last several days after the precipitation is over in extreme cases. Snow, you see, has sticking power … literally. A couple of years ago during the onset of the Montana rut, the northwestern part of the state was buried by a 24-hour-record 42 inches of snow! The rut had been progressing nicely, but with the snow, proceedings mired to a standstill. Only pure luck saved the season for me when I stumbled upon a big 12-pointer grossing 182 the morning after the big snowfall. But with friends in town to hunt, I had to keeping slugging it out with the snow, which received two more feet of reinforcements a couple of days later, in an attempt to help them get a deer. After several days of hunting, we had nothing to show for our considerable efforts and had found precious little deer sign to encourage us. Then, I finally figured out what the deer were doing … or not doing. What I found was very interesting.

The deer were virtually trapped by the deep snow. Unable to travel long distances, they retreated to nearby timbered areas with thick overhead canopies, where they held up. In these little enclaves, pockets of deer numbering from a handful to many dozens carried out a modified version of the rut. Whatever bucks were trapped with the group did the breeding. The dominance hierarchy went no further than the top dog in the local gathering. There was precious little traveling between groups of deer. Sign outside those pockets was almost nonexistent. Traditional rutting grounds I had hunted successfully in years past were practically devoid of tracks. In one instance three days after the last snowfall, I drudged nearly three miles across one of my favorite rutting hillsides and cut only two sets of tracks. Only after I began to locate the tightly bunched pockets of deer, mainly by following the few tracks I could find, did I find any evidence that the rut had resumed. All in all, I’ve never seen the rut so totally disrupted as it was by the dumping of nearly six feet of snow in less than four days. 

Typically, extremes in weather only temporarily delay and/or alter normal rutting activity. I’ve seen flooding along major rivers disrupt and relocate rutting activity. In Canada, chinook winds, which are strong, warm winds coming off the east side of the Rockies, can last for several days and curb rutting activity. A couple of years ago, chinook winds gusting up to 50 mph persisted the entire week I was hunting the famed Mosquito Indian Reservation. Though it was the traditional peak of rut, 10 hunters only killed two bucks that week. One was mine – a big 9-pointer grossing 167. The other was a “mistake” buck shot during a desperation drive on the last day of the hunt. In most cases, the effects of heavy rain, high wind and the like pass quickly, allowing the rut to resume with catch-up fury.  

Herd Condition

The physical condition of the deer within a herd can impact visible rutting activity and even breeding itself. When a herd is in poor condition, the start of breeding is often delayed and, once underway, breeding is less intense and more spread-out. This watered-down breeding cycle, now more widespread than ever before because of chronic overcrowding, is called a “trickle rut.” There are also causes for short-term poor herd condition, such as drought, mast-crop failure, flooding and even disease, that can flatten out the rut in a given year. For instance, severe drought in South Texas or a poor acorn crop in an area with populations heavily dependent on mast often leads to poor deer condition and a trickle rut. During such pitiful ruts, I’ve even heard hunters declare that there was no rut at all that year. But, a full compliment of fawns was born the following spring so breeding did take place. It’s just that hunters didn’t see the ritual activity normally associated with the rut.

If all this seems too confusing, you can adopt the policy of my old hometown fishing buddy, Wilbur Pridgen. When asked about the best time to go fishing, his answer was always the same: “Don’t worry about it. Just go everyday and you’ll be there when they bite.” That’ll work for deer, too!  

(Editor’s note: This article was excerpted from David Morris’ new book, Advanced Strategies for Trophy Whitetails.”)