10 Things We Know About Mature Buck Movements

August 27, 2013 By: Matt Ross

Technology is amazing, isn’t it? As I type this article on my laptop, on a plane 20,000-plus feet up, heading to yet another NDA event, I have access to the Internet! When we land and I boot up my cell phone, I will simultaneously have the ability to take a high-resolution photo, attach it to an email or text message (that I can choose to recite through voice-recognition software), insert this very same document from a “cloud” based holding spot, and then send all of it to a co-worker, hundreds of miles from where I’m standing, to view and post on the Internet. Then I can use my phone as a Geographic Positioning System (GPS) unit to quickly and efficiently guide me to my destination. Oh, and I can also use it to call my wife to tell her I landed safely. Admittedly, it’s hard to wrap your mind around how much technology has become integrated into our everyday life.

The same is true with deer research. We now have the ability to basically strap my cell phone to a buck’s neck and see where he is every minute of every day; I can even get his location texted to me, too. Now that’s crazy.

GPS-based whitetail research has been around since the 1990s, but advances in collar technology the past few years have drastically increased accuracy of the data and have allowed us to look at aspects of deer behavior, specifically mature buck behavior, differently than ever before.

I had the pleasure of giving one of the educational seminars at the QDMA’s 13th Annual National Convention, entitled Mature Buck Movements: Groundbreaking Research. I compiled, analyzed and presented the results from every GPS-based research project I could find that had to do with bucks between the ages of 2.5 and 7.5 years old. This included studies that looked at resource use, home range, and daily movements, as well as those that investigated influences from age, breeding, weather, the moon and even hunting pressure. All data were from the past 15 years or so, and I even spoke to several researchers who are overseeing ongoing projects and tracking bucks that are wearing collars as you read this.

The feedback from my Convention seminar was so positive that we decided to relay a brief summary of this information to all NDA members and interested deer hunters, not just those who attended our Convention. So, here are 10 things we know about mature buck movements today.

Bucks are individuals. Every buck is different. Numerous studies have shown that a buck’s home range size is highly variable and is not strongly correlated to age, daily movements or any number of other factors. Mature bucks are not clones of one another, and many display more individualistic behavior than what was previously thought. We can no longer say, “The older a buck gets the bigger his home range.” That is simply not true. In fact, if anything their home range shrinks as they age. Like people, it appears that some bucks tend to be homebodies and have relatively small home ranges, and some bucks are travelers with expansive home ranges. Some are on their feet and move a lot during a 24-hour period, and some don’t. These traits are found in all age classes and are maintained by the individual buck throughout his life.

Deer move most at dawn and dusk. End of story. Like taxes and death, you can count on two things when talking about mature bucks: they move most at dawn and dusk, and during the rut. Deer are crepuscular. It’s built into their DNA. It doesn’t matter what month of the year you are talking about, pretty much every study out there shows that the time of day bucks are most active is at sunrise and sunset. Can you kill a mature buck during the middle of the day? Sure. But if you want to hedge your bet, be in a stand during those magic hours. And the time of year they are most active is…? You guessed it, the breeding season. Keep these things in mind when trying to predict when that buck you’re after will be on his feet.

Home range can shift and grow seasonally with outside influences. Even though a mature buck lives within what biologists call a “home range,” where he is located 90 to 95 percent of the time during the calendar year, researchers have found that a variety of factors (food, cover, etc.) can greatly influence where that buck may be within that home range during different seasons, and his home range likely expands during the rut.  They also found that the intensity of use of that home range increases from summer into fall, and apparently it is not random.  Research from Texas recently showed that mature bucks only used 30 percent of their home range during the rut, had two or more points of activity that they focused on, and they re-visited these locations roughly every 20 to 28 hours. What’s more, these same sites were targeted by numerous other collared bucks, possibly supporting the theory that bucks space their visits to doe groups to continually assess female receptiveness.

There’s no place like home. Research also suggests that as bucks age, site-fidelity increases. This is a fancy term that essentially means bucks are less likely to leave or change where they live as they get older. If you think about it, that totally makes sense. Why leave a place where he may have survived two, three or even four or more years? Moreover, every project I looked at that estimated a buck’s core area (where he spends at least 50 percent of his time) showed that mature bucks really only use 5 to 10 percent of their home range for core area activities; and, most of those core areas were between 60 and 85 acres. That really narrows it down when trying to locate a buck’s so-called “bedroom” and gives hope to the small-acreage hunter trying to attract and hold mature deer.

Deer take short vacations. Today’s increasingly accurate GPS collars have taught us that deer (does and bucks) go on excursions, or brief trips outside their established home range. They do it regularly and even on well-managed properties with high-quality habitat. Excursions have been documented across various landscapes, in all age classes, and just about year-round; however, there is certainly a huge spike in this type of movement during the rut. Unfortunately, there is no way to predict when and how far a buck will go. The thing to remember is that if you’re hoping for a glimpse of a mature buck, this means increased opportunity. On the other hand, if you’re hoping to see young bucks survive the season, it means increased risk. All the more reason to form a QDM Cooperative with your neighbors.

Regardless of weather, bucks move most at dawn and dusk. With the exception of one study from South Texas in the summer, numerous studies from Texas to Maryland suggest that weather has little or no influence on mature buck movements. I know, hard to believe, right? But, at least to-date, researchers have thrown everything at this concept and collected a lot of data, and still nothing. As I said before, bucks move the most at dawn and dusk, period. One three-year study in particular produced almost half a million GPS data points from over 40 bucks and attempted to correlate weather variables such as temperature, relative humidity, barometric pressure, wind speed and precipitation – and no correlation was evident. In cases of extreme weather events, like northern yarding behaviors in response to winter weather or like the Mississippi flood in the spring of 2011, there is some short-term response. However, site-fidelity is so strong that in one case a research project lost nearly 30 percent of their collared bucks to flooding because those deer refused to leave and simply ran out of food or drowned; the others returned to the study site immediately after the water receded.

Regardless of moon phase, bucks move most at dawn and dusk. Similarly, in four separate GPS research projects from around the country each found that moon phase had little or no influence on deer movement. Three of these studies dealt directly with bucks and looked at the impact on daily, diurnal, and nocturnal activity; still, deer were crepuscular in every case regardless of moon phase. One project, contrary to popular belief, even found that deer were more active and moved earlier during the day following a full moon. Bottom line: No peer-reviewed scientific data to-date has revealed a correlation between moon phase and breeding dates and/or deer movements. However, numerous studies have shown a correlation between photoperiod (the length of daylight) and breeding dates. You do the math.

Bucks respond quickly to hunting pressure. How many times can you hunt before that buck you’ve been after catches on? Well, luckily a few studies that had GPS collars on mature bucks wondered the same thing; from this, we know that deer do respond to some level of hunting pressure. For example, on two projects where deer had spent considerable daytime hours pre-season in open fields and food plots, the same individuals intentionally avoided those same areas until after dark once the season opened; the fact they continued to use them confirmed their value. OK, so that response may be obvious to most hunters, but at least the GPS collars proved that daytime avoidance and nocturnal use occurred. Another study tried to quantify how much is too much hunting pressure. They found that at 1 hunter per 250 acres, minimal effect could be seen in the way bucks move. However, at 1 hunter per 75 acres bucks responded by choosing thicker cover, they traveled less, and observation rates/hunter success decreased; and, once the season opened, it only took three days for bucks to change their behavior. I’m not saying that this threshold is the same where you live, but clearly there is a breaking point where having too many people in the woods affects your ability to view and harvest mature bucks. It is likely impacted by topography, amount of cover and hunting technique. You’ll simply have to collect your own data where you hunt to figure out where that point is.

There is no silver bullet. Perhaps the biggest lesson learned as it pertains to predicting exactly where any mature buck will be at any given moment: we can’t. There are too many variables to consider. Even with all of the latest technology at our disposal, you still need to use some of that old fashioned “woodsmanship” skill that was a critical necessity of our forefathers to 1) read the landscape, and 2) ultimately “see” how a buck uses it. I think that’s a good thing. It keeps us humble.

There’s a lot more to learn. Although I say we “know” the above nine items about mature buck movement, even today after decades of research we are learning new things about white-tailed deer ecology, biology and behavior. They are amazing creatures, after all. Fortunately, thanks to QDM, there are far more mature bucks in the woods to study and hunt this fall!

Thanks to the following for contributing valuable information to what we know about mature buck movements: the University of Georgia, Mississippi State University, North Carolina State University, Auburn University, Louisiana State University, University of Tennessee, Texas A&M-Kingsville, University of Arkansas, Ceasar Kleberg Wildlife Research Institute, and the Samuel Roberts Noble Foundation.

No other deer hunting organization or publication keeps an eye on deer research like NDA and our magazine, Quality Whitetails. NDA even directs funding to projects that can improve our knowledge of deer, make us better hunters, and help secure the future of deer hunting… nearly half a million dollars since 2006! Stay on the forefront of new deer knowledge, and help directly support new research into deer behaviors, by joining NDA today!

About Matt Ross:

Matt Ross of Saratoga Springs, New York, is a certified wildlife biologist and licensed forester and NDA's Director of Conservation. He received his bachelor's in wildlife conservation from the University of Massachusetts-Amherst, and his master's in wildlife management from the University of New Hampshire. Before joining the NDA staff, Matt worked for a natural resource consulting firm in southern New Hampshire, and he was an NDA volunteer and Branch officer. He and his wife Sadie have two daughters, Josephine and Sabrina.