With several major deer movement studies now complete, do we know anything new about buck travel?
Slow is the only way to describe deer movement over the first several days of my Ohio hunt last fall at Heartland Wildlife Institute’s proving grounds. Having bagged a bruiser on the first afternoon the previous year, my expectations were high. A review of trail camera pictures collected over the intervening months drove them even higher. But after three days, none of the six hunters in our group had even seen a mature buck. That was all about to change.
The first inkling came as a text from our unofficial guide, Brian.
“Tim just shot an 8-pointer.” It was only 2:30, and Arrowtrade editor Tim Dehn, also a veteran of Heartland hunts, wasn’t likely to shoot just any buck. Over the next few hours, I saw three racked bucks, including a couple that would have looked nice on my trophy room wall. Unfortunately, all three passed by as if they had somewhere else to be.
That wasn’t the case for my companions. Upon returning to camp that evening, I learned that Bob Banks and Jack Weber shot bucks out of the same blind, and only minutes apart.
On another nearby parcel, Sabrina Simon shot a bruiser 4x4. Two days of nothing, then, over the course of just a few hours, five hunters at four different locations had all seen mature bucks. It was as if someone had flipped a switch. That caused me to ponder just why all those mature bucks suddenly got up and moved.
At one time or another, we’ve all dreamed about being able to monitor the precise movements of a mature buck for a day, several days or an entire season. Imagine how valuable that information would be. Most of us never will, but a growing number of biologists do it every year. And what they’re learning has some direct and very valuable application for those of us hunting older bucks.
The foundation of a sound scientific experiment is the hypothesis – a statement of what the scientists conducting that experiment believe to be true. They then set out to either prove or disprove the hypothesis by collecting and analyzing data. Some experiments may include several hypotheses.
Let’s pretend to be scientists for the moment and develop our hypotheses based on what we think we know about mature buck movement.
Hypothesis 1: A white-tailed deer’s home range is approximately 1 square mile.
Hypothesis 2: A buck’s home range increases as he gets older.
Hypothesis 3: Once the rut begins, bucks leave their home range, traveling far and wide across the landscape in search of does.
Hypothesis 4: During the rut, mature bucks move more during day-light hours.
Hypothesis 5: Deer move more in daylight hours during a new moon and less during a full moon.
METHODS AND MATERIALS
The next step in the scientific method is to conduct an experiment. Fortunately, that part’s been done by real scientists. Tracking whitetails was once done with radio collars that were lucky to locate a deer once a day. With today’s GPS satellite collars, they can pinpoint locations every 15 to 20 minutes, often over a period of several months.
I’m not sure where the square mile notion originated, but is has been perpetuated for generations. And, based on what we’ve learned since, it’s a reasonably good average. It is an average, however, and home range sizes can vary considerably.
For every buck home range that’s smaller than a mile, there’s another that’s larger, and the differences can be considerable. Studies from Louisiana, Maryland and Pennsylvania showed home range sizes for adult bucks averaged from around 250 to 500 acres. Meanwhile, a Texas study found home ranges averaging over 2,000 acres. Average those out and you come pretty close to our square mile estimate.
Home range size is influenced by several variables, not the least of which is available food. The more food available and the more nutritious the food, the smaller the home range.
And as food availability can vary by season, so can home range size, shrinking in spring and summer as food becomes more abundant and expanding in fall and winter when food is more scarce. It also could be affected by population size, as well as age and sex ratios.
Here again, the studies help. What researchers found is that 2½-year-old bucks tend to have the largest home ranges. Bucks 3½ to 6½ fall in the middle, and those 7½ years and older are much more likely to stick close to home.
Again, these results are averages. Just as every area is different, every buck has an individual personality. Some older bucks might have fairly large home ranges, but those home ranges were probably even larger when that buck was younger.
CUT TO THE CORE
As hunters, we’re much more interested in core area, that portion of a buck’s home range where it spends at least 50 percent of its time. Several of the aforementioned studies showed core areas of under 100 acres. These, too, can vary depending on food availability, deer densities, and age and sex ratios.
In areas with low deer density, bucks might have to travel farther to find a receptive doe. Conversely, increased competition for mating can expand core areas. And if we’re after older bucks, we’ll want to know if there are any age differences.
It turns out there are. A Texas study found differences among age classes, with yearlings and mature bucks traveling the least during peak rut. In the case of yearlings, they’re less experienced, generally have smaller home ranges and less fat, meaning relatively greater risks associated with venturing farther from home.
Meanwhile, mature bucks have more experience and usually know where to find hot does. The research suggests they do, as evidenced by their looping travel routes in which they often revisit the same areas. But I’m getting ahead of myself.
Let’s take a look at our third hypothesis and how bucks move during the rut.
We know they move, and it turns out they employ a few different strategies to locate a mate. One method, sometimes referred to as a Levy walk or excursion, occurs when a buck heads off on a relatively straight line for some distance (a mile or more) outside his core area. This one fits our hypothesis. The other, called a Brownian walk, involves revisiting the same areas frequently.
A Texas study found bucks, even individual bucks, use both strategies. However, which they use can vary with timing and age.
Because hot does are more scarce early in the rut, bucks must travel farther to find them. As the rut peaks, more bucks switch to shorter, Brownian walks. Researchers concluded this is partly because bucks move very little when with a standing doe, and partly because they don’t have to travel as far to find another.
Yearlings and mature bucks were least likely to go on excursions, particularly during peak rut. Meanwhile, 2 1/2-year-olds were more likely to continue their excursions through the peak of rut.
Researchers attributed yearling fidelity to less experience, smaller home ranges and less fat reserves, all of which increase risks associated with venturing too far from home. They speculated mature bucks are more experienced and know where to find does. The middle-aged bucks’ continued wanderlust could be because they’re less experienced at finding does, and because they encounter increased conflicts with older males tending hot females.
Perhaps the most interesting finding was that most bucks did not wander widely during peak rut. Instead, they utilized only 30 percent of their home range. Most buck visits were concentrated on two or more focal points of between 60 and 140 acres, which they revisited about every 20 to 28 hours. The focal points of several individual bucks overlapped during peak rut.
Because does come into estrus for about 24 hours, the researchers speculated bucks might be spacing their visits to assess female receptiveness.
Human presence is another factor. Maryland researchers documented evidence of deer avoiding permanent stand locations during daylight hours. They suggested it could be the result of deer learning to avoid specific locations, or possibly even structures, because of repeated negative interactions. Those interactions could be as subtle as a whiff of human odor.
Another study from Mississippi State University found that deer recognized hunting pressure and initially decreased both their day and night movement. Movement eventually increased over time with sustained human presence, but the deer covered much less ground, presumably sticking more to undisturbed sanctuaries. One can probably assume the effect is greater with older bucks.
That leaves us with two more hypotheses to test. In addition to how far and how often bucks traveled, researchers also looked at when bucks move. In general, they found that even during peak rut periods, daytime movement followed the same general pattern of peaking around dawn and dusk.
A North Carolina study found somewhat similar results with regard to the moon. Deer movement remained most active in twilight, regardless of moon phase or position. Peak movement occurred near dusk in all phases except the new moon, when movement peaked near dawn and lasted a little longer into the early morning.
There was little effect during the first quarter, but midmorning movement rates were highest during the non-quarter periods. Although still relatively low, midday movement tended to be greatest during the full moon. Late afternoon activity peaked during the last quarter.
After examining the study data, we end up with mixed results.
A one square mile home range is a good starting point, but you can narrow that down considerably with some extra scouting work, especially if you’re after an older buck. He might leave his core area temporarily during the rut, but will likely return within a day or two. His excursions will most likely take place during typical movement periods of dawn and dusk, regardless of moon phase.
I approached the fourth day of my Ohio hunt with mixed feelings. With four adult bucks taken in a few hours on a rather small area, it seemed the odds were stacked against me. But the switch had been flipped.
The morning started much as the week had: slowly. It ended similarly, when one of the bucks I’d seen the night before cruised by, obviously on an excursion. This time, the food plot held what he was seeking: a pair of does.
Instead of continuing on, he circled downwind and perhaps caught a whiff of Eau de Estrus. When he burst back into the open a mere 40 yards away, my crossbow was already up on the sticks. I had merely to find the buck’s vitals in my scope and squeeze the trigger before an arrow was on its way, capping off an incredible 24-hour period of buck movement.
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This article was published in the August 2014 edition of Buckmasters Whitetail Magazine. Subscribe today to have Buckmasters delivered to your home.