Where Do Whitetails Go? Here's What Science Says

Excursions, hunting pressure, the weather — all affect deer movement. Here’s what science says about it.

Where Do Whitetails Go? Here's What Science Says

In mid-summer a friend drove me around his hunting area for advice on some habitual work. As we covered the area he sadly recounted his problem in holding bucks on his property. “I’ve got good bucks on camera in August, but come gun season they are gone,” he lamented. “I need to get some food plots out and do something to hold these bucks on my property.”

The property was large, and some of it extremely rugged, steep and rather impenetrable. When I asked him about hunting that nasty part of his lease he indicated it was just too thick to hunt. Hmm. I decided to give him my opinion, but I’m not sure he wanted to hear it. I told him that my guess was come gun season, adding some hunting pressure, his big bucks would still be on his property and in that nasty stuff.

When the bucks on trail cam in August disappear, maybe they are just in thick cover, but there can be other factors causing this as well. Let’s consider some.

About 15 years ago, Dr. Grant Wood did a study in Missouri that showed around 40 percent of all mature bucks left their home range in early fall. They’d go as far as 5 miles away, and some returned the next year, but some never returned. If that is happening on your property then remember that though you may lose some older bucks, you also may be gaining some good bucks from surrounding areas. If you’ve got good habitat on your area, those mature bucks that wandered in just might stay.

Over the past 15 years we’ve heard a lot about “excursions.” Not all researchers define excursions in the same way, but basically an excursion is when a deer leaves its home range and goes several miles, returning within a relatively short time (a day to a week). When excursions were first reported in Maryland it was thought that the behavior was only bucks and that it occurred only in the rut. Today we know it can occur year-round and we know does also take excursions during the rut.

Consider the results of this recent University of Tennessee study where they followed 10 collared does and 10 collared bucks. They learned seven bucks took long excursions out of their home range once in the pre-rut, four times in the peak-rut and twice in the post-rut. What about the does? Six of the 10 took excursions in the pre-rut, rut and post-rut. The most active time for does to take long hikes was in the pre-rut. One conclusion of this study was that excursions are more about breeding than we once believed.

Maybe so, but if that is true, why do bucks take excursions in the spring? A recent Pennsylvania study sheds more light on buck excursions. They put collars on 13 bucks 2½ years and older and found that nine of them made excursions between April and June. Six bucks made two such excursions during that time. The average distance covered was 2½ miles, but one buck went 5 miles. The average time of the excursions was 22 hours. My point in mentioning this study is that we still don’t know what precipitates bucks taking off on these “hikes,” but they are one of the possible reasons that you don’t see the bucks that you knew were on your property before the season.

What if a deer just shifts its range during the year? That might explain the disappearance or the appearance of bucks on some of your trail cameras. A recent Master’s thesis done by Andy Olson found that in Pennsylvania, home-range size varies by season and tends to follow the food. The core home range (defined as the area where a deer spends more than 50 percent of its time) does the same. In the fall, the home range for 19 mature bucks was 900 acres and the core range was 116 acres. In the winter, the home range was 800 acres and the core range was 115 acres. The spring home range was 717 acres with a core range of 100 acres, while the summer home range was 415 acres with a core range of only 60 acres.

His conclusion was you can create more and better habitat and this tends to keep the deer on your property. They may move around a bit as the food availability changes, and they still might go to the thick cover when there is hunting pressure, but creating food will help you know where they are. Where possible, put in small food plots with clover and chicory. If the timber and terrain doesn’t permit food plots, then get sunlight on the ground with some small-sized timber cuts.

A recent Louisiana study of collared mature bucks showed that some bucks during the rut had two home ranges. They spend time in one home range then take off on an excursion and spend days at the second home range. These biologists concluded something that we hear more and more: each buck is an individual and this applies to everything they do including rutting and movement. If you have a mature buck that moves very little during the rut, and his home range is in nasty terrain, you may never see that guy.

Another reason you might not be seeing bucks during the rut is because you aren’t out there at the right time. A posting on Penn State University’s Deer Blog showed collared bucks daytime rut movements were the least from 8 to 11 a.m., but comparatively high from 11 a.m. to 2 p.m.

What impact does hunting pressure have on deer movements? The first study ever done on the impacts of hunting on bucks was on the Eastern Shore of Maryland. Dr. Gabriel Karns put collars on nine bucks that were 2½ years or older and looked for changes in their home range before, during and after gun season. He found there wasn’t enough hunting pressure to cause any shifts in the buck’s home range, but he did see a decrease in buck movement and activity from the pre-hunt to the hunt period.

The next such study was done in Oklahoma where 27 bucks aged 2½ to 6½ years the first year and 2½ to 8½ years the second year were collared and followed. Combining data for both years, hunters saw 38 percent of the bucks on the opening weekend of a 16-day season. The second weekend they spotted 23 percent of the bucks, but only 3 percent by the third weekend. Of course this could be explained if the bucks left the property, which some did. But the graduate student from Mississippi State University who did this study found that buck movement decreased from the beginning of gun season to the end. Hunting pressure caused the bucks to hole up. If they move less, you see less. Simple.

Another aspect of this Oklahoma research was that they looked at deer movement in areas with different hunter densities. One area had a single gun hunter per 75 acres, and another had a single gun hunter per 250 acres. You might expect a high density of hunters would cause bucks to move more, thus increasing the chance for a hunter to see them. On the other hand, bucks chased by higher hunter numbers might hunker down in thick cover making them less likely to be seen. In this study, the number of bucks seen per hunter/hour was similar in both high-density and low-density areas. Go figure.

Duane Diefenbach with the Pennsylvania State University Cooperative Fish and Wildlife Research Unit followed 40 collared bucks and does in the early archery season through the rut and gun season. As you might expect, deer movement didn’t change much during bow season, because archery hunting has a minimal effect on deer movements. But the response to Pennsylvania’s large number of gun hunters was much different than the other studies.

Diefenbach found what I suspected was happening at my friend’s property. Deer move away from gun-hunted areas, go into thick cover and move a lot less. Diefenbach found that even on public land, where hunter density is very high, deer move to thick, unapproachable (based on wind and habitat) cover. They move around a bit during the day (aha, they are not totally nocturnal even in the gun season), but the areas they spend time in are areas so remote and so thick that hunters do not go there. To prove the point, note that only about 10 percent of Diefenbach’s collared animals were harvested. He also showed that when the hunting pressure got high in gun season, the home ranges of his bucks and does got smaller.

What is the take-home message here? During the hunting season, there are lots of reasons why you may not see all the bucks you had pictures of in August. Some reasons, such as excursions, are totally out of your control. However, there are things you can do to improve your chances. First, if in forested habitat where you can’t create food plots easily, consider making a number of small openings in remote, thick cover. Maybe five 100-foot diameter openings in a ¼-mile area. Set your stands in this area according to wind conditions and pick sites that provide easy, quiet, access.

To me, the most interesting research we’ve learned over the past 20 years is how individualistic bucks are. When pressured, some will hunker down and others move. All this makes the challenge of hunting these great animals that much greater and that much more exciting.


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