Thanks to GPS and other tracking technology, scientists have the ability to closely monitor whitetail movements. Every year, and all across the country, a multitude of studies are performed and hundreds of deer are fitted with GPS collars as researchers try to figure out, among other things, where deer travel during the course of their lives and especially throughout hunting season. Some of their findings are quite interesting.
Crepuscular at Heart
Whitetails have often been described as crepuscular animals. By definition, crepuscular means “of, resembling, or relating to twilight.” It’s no surprise, then, that mature bucks move most at dawn and dusk. Period. Forget the weather. Forget the rut.
A number of years ago, biologist Matt Ross wrote about this for the Quality Deer Management Association (now the National Deer Association, www.deerassociation.com): “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.”
Ross stated that three different studies also dealt with whitetail movement in relation to moon phase. In every instance, deer moved most during dawn and dusk, regardless of moon phase or stage of the rut. The bottom line, Ross writes, is that “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 (length of day) and breeding dates.”
Where Bucks Rut
In the March 2018 issue of Deer & Deer Hunting magazine, researcher Dr. Steve Ditchkoff of Auburn University writes about the habits of Deer 41 during breeding season in one of their studies. Specifically, he discovered that the buck’s breeding range changed each year for the three years they tracked it. Dr. Ditchkoff writes: “In 1995, he primarily utilized the western section of his home range, in 1996 he spent most of his time 1/2 to 3/4 of a mile south of that area, and in 1997, he rutted primarily at the northern edge of his home range, which was 1 1/2 miles north of where he spent 1996.”
Dr. Ditchkoff makes an interesting observation when he suggests that you might get trail camera pictures of this buck all year long on your property, but never actually have an opportunity at this buck during hunting season. In fact, almost all of the deer in the study moved or shifted their patterns in some way once the rut arrived, and for most of us who don’t own or hunt on large tracts of land, a shift of half a mile or more may as well be ten miles. Once a deer is our of our area of focus, whether it’s on public or private land, it pretty much drops off of our radar.
Hunting Pressure Kills
Research suggests that one hunter per 250 acres has little to no effect on whitetail movements. But one hunter per 75 acres can be enough to push bucks into thicker cover and cause them to travel shorter distances during daylight hours. A common misconception, though, is that all deer vacate public land in favor of private land during hunting season. In extreme instances this can happen (I once read a story about a buck that relocated nine miles in one fall because of hunting pressure), but by and large, rather than leave a tract entirely, deer will simply adjust their behavior within that area.
A Penn State University study tracked a whitetail they dubbed Hillside Doe because her home range was a hillside. As hunter activity increased around bear season and Thanksgiving, her movements remained relatively unchanged, with her core area within 200 yards of a road. Come Sunday, the day before opening day of Pennsylvania gun season, her routine shifted completely as she sought the steepest and thickest part of her hillside to bed each day. She chose to bed in the most rugged terrain during daylight, but every night she was right back in her comfort zone next to the road. By the end of hunting season, she began bedding close to the road once again.
Another PSU study found that the average hunter chooses a stand location less than a third of a mile (approximately 600 yards) from their vehicle. With that in mind, it’s easy to see that a small movement can be just as effective as a big one when it comes to deer avoiding hunters.
Shrinking Ranges
Many studies show that a buck’s core area (where it spends at least 50% of its time) shrinks as it matures. On a broader level, a mature buck’s core area typically consists of 5-10% of its home range. However, the home range of a mature buck often varies. In some studies, done in areas with good habitat, home ranges were less than one square mile, which means that at least 50% of a mature buck’s movements were done in a 32- to 64-acre zone.
A South Carolina study tracked fine-scale movements of 37 bucks on 6,400 acres. The average home range was only 350 acres. Of 10 collared bucks 4.5 years of age, the smallest home range was 108 acres, while the largest was 521 acres. Keep in mind, though, that this was high quality habitat. The actual size of a home range, as well as core area, will expand or contract according to the availability of food, cover, and females during breeding season.
There’s no doubt that GPS and other tracking technology has provided a wealth of information and insights into the world of whitetails. Regardless of the study or its intent, though, there has been one similarity that has persisted in every one of them, and it’s this: whitetails are incredibly individualistic. Research can do a great job of telling us what deer do, but it can’t always explain why they do it. And that’s what keeps us coming back to learn more.
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