Understand Why Deer Move
There is a fair amount of literature, both popular and scientific, that discusses the factors that affect deer movement. The problem is that there are a lot of variables that can affect deer movement, and this complicates most scientific studies. These variables include; hormones and breeding, food, moon phase, human pressure, wind, temperature, barometric pressure, buck to doe ratio, dispersal, etc. The list goes on and on, and we can’t begin to cover it all. So what we have tried to do is look at the science and present the results of what researchers have found relative to many of these variables and deer movement.
One problem is that one study done in one location gives different results on the same variable as another study done somewhere else. Part of the problem is that when studying one variable (such as deer movement and temperature) the results may become clouded because of other variables (such as barometric pressure or the moon cycle) acting at the same time. We can speculate about the results and the differences in results from studies done in two different areas, but it is just speculation. So, we present the science and leave the interpretations up to you. Of all the chapters in this book, this was the hardest to collate simply because deer don’t talk. Still, we believe there are some things in here that almost certainly can help you better understand why deer move. And knowing why they move may well help you to understand when and where they will move.
At the 2006 Quality Deer Management Association’s annual convention, there were several interesting presentations on deer movement. Dr. Mark Conners presented data on deer movements on Chesapeake Farms on the eastern shore of Maryland. He looked at the travel distance by time of day and found the peak time for deer movement was 5-7 AM and in the evening. No surprise here.
In August he found that in the AM, bucks moved about 330 yards, with little movement in the day, then movement of 435 yards in the evening. In October he found they moved between 330 and 650 yards in the morning and 220 to 330 yards in the evening, but there was a lot of individual variation in daily movements at this time. Come November the individual buck movements were highly variable. Some moved a lot more than others. And some bucks moved continually throughout the day. More on this study in a minute.
Dr. Mickey Hellickson gave a paper on deer movements at that same convention and noted that there are two major factors that affect movement regardless of the weather; the need to breed, and the need to feed. Obviously deer must do both, but there is no doubt that weather and other variables affect the need to breed and the need to feed. We shall present Dr. Hellickson’s information, and that of others in this chapter. Hopefully you will find some gems that will allow you to be more successful.
Does Weather Determine Whether They Move?
Excuse our play on words, but among hunters there is a lot of discussion on weather and deer movement. We’re going to start this part of the chapter with some very recent, and interesting, data from South Texas.
Dr. Mickey Hellickson put motion-sensitive collars on 43 bucks in South Texas in areas where there was little hunting pressure (ranches where only bucks 5 ½-years-old or older could be harvested). These collars allowed him to not only know where the bucks were, but whether they were moving or not. He assigned the bucks into four age classes, and noted their movements as being inactive (bedded, standing) or active (feeding, walking, running). He followed these bucks 24 hours a day during the pre-rut (Oct 1-Nov 31) and the rut (Dec 1-Jan 10), collecting data for six consecutive years. With this super data he correlated buck movements to various weather-related variables.
Based on his data and observations, Dr. Hellickson believes that deer movement is caused by the two basic factors mentioned above. The first is their need to breed. For bucks, testosterone is the driving force that gets them into breeding condition. The second factor is their need to feed. These two factors determine why and when they move. Weather, moon, human pressure, buck to doe ratio, and other things can enter in, but when it comes to deer movement, these are the keys.
Let’s look at the interesting trends that Dr. Hellickson found. First, 57 percent of the time, bucks are inactive. This means that over half the time they are either bedded or standing in one spot. Assuming that 30 percent of that is bedding at night, there is another one-quarter of the 24 hour day when they are fairly inaccessible to you. This explains why we don’t have bucks running around under our tree stands or near our ground blinds all the time. When you look at the big picture it becomes obvious that bucks don’t move around all that much. If he is bedded or not moving (as they are 57 percent of the time in South Texas), you aren’t going to see him. We can spot and stalk them, but that is not done all that much for deer. This bit of data tells us how important bedding areas are for deer. Very important. The closer you can set up to those areas without buggering them, the better chance you have of seeing a buck when he is active.
The second thing Dr. Hellickson found was that daytime movements peak when you thought they did; 7-9 AM and 6-7 PM. Third, on a yearly basis, deer are most active (move more) right before the peak of the rut and they are the least active in the spring. Fourth, during the rut they tend to be active all day, decreasing at night. Fifth, the older a buck gets, the less he moves. We discussed this a bit in the previous chapter. As noted in Chapter 8, not only do home ranges get smaller as bucks age, their core home range (where bucks spend 50% of their time) gets really small. More on that later.
Sixth, young and middle-aged bucks move more than mature or old bucks. His seventh finding is most interesting. From observations made on movements of 43 different bucks, he found that there is a lot of individual variation in buck movements. In fact, he found that some bucks move four times more than other bucks. For example, remembering that all bucks are only active 43 percent of the time, he found one 6.5-year-old buck that was active 87 percent of the time, while an 8.5-year-old buck was only active 18 percent of the time. Thus, they are a lot like people. There are some older guys who walk every day, climb mountains, and are just plain active, and others who sit around and watch TV a lot.
Dr. Randy DeYoung also found a big variation in the amount that bucks move during the rut. Some stay within their home range and move a lot. Others stay within their home range and move very little. And some older bucks leave their home range and set up a new range, staying for several days to months, then return to their original home range. Finally, some bucks move out of their home range just during the peak of the rut, stay a few days, then return. The conclusion is that bucks do not always read the book, and individual variation in movements during the breeding season are common. That might explain why your scouting trips gave you great optimism, only to be dashed by reality once the hunting season started. Where did they go?
This individual variation in behavior of bucks also shows up in breeding behavior. In Chapter 10, we’ll talk more about this. For example, some old bucks don’t mate does at all. Other, scrubby old bucks that have poor antlers and low weight mate more than big, older bucks. What’s that all about? I’m not sure but it shows that individual variation in buck mating behavior occurs more than we ever suspected. Same for buck movements.
Dr. James Kroll collected data in Texas and found that feeding activity was greatest in the late afternoon for bucks over 3½-years of age. In fact, these older bucks moved less than other does and bucks, except for the late afternoon. One other point. Kroll compared deer activity from an area in Michigan to one in Texas and found that afternoon deer activity tended to start earlier in Michigan. He postulated that the hot Texas temperatures caused deer activity to occur later in the afternoon.
There is a fair amount of other data on temperature and deer movements. Again, the Hellickson study has data on this that is surprising to say the least. He found no correlation between temperature and deer movements. Remember though, this is South Texas. Even though there isn’t a study with the type of data Mickey Hellickson collected, there are a few studies from the North that show that temperature is a factor for deer movement. In fact, Charles Alsheimer and others believe that in the fall, buck movements decrease sharply when you get above 45 degrees. Not so in South Texas.
Jim Tomberlin’s thesis data from Maryland showed that buck activity decreased (especially in early morning) as the changes in hourly temperature increased in late September through the first week of November. But in the post-rut (Nov 26-Dec 16), buck activity increased as change in hourly temperature increased. Of interest is the fact that warm weather affected buck movement, except during the peak rut. During the peak rut you need to be hunting, regardless of how warm it might be.
Several years ago I was bowhunting in early November in Illinois. Daytime temperatures soared into the 80’s, and buck sightings were low. On the third day, I asked the landowner where the coolest place was on his farm. He took me to a stream bottom in a small, but steep, ravine. When we hit the stream, it was almost dry. There was a trickle here and there, and a few small pockets of water, but very little moisture. However, as soon as we got to the stream bed, we noticed a temperature decrease. It was amazing. There had to be a 10 degree difference. We hadn’t walked fifty yards down stream when a huge buck jumped from his bed, in lose gravel right beside the water. I snuck in there before daylight the next morning and shot a dandy buck as he walked up the stream bottom.
Few will argue that unseasonable hot weather in the North, during the rut, will really curtail bucks movements during the day. They just avoid the heat. Charlie Alsheimer uses 45 degrees as a rule of thumb for deer movement in New York and elsewhere in the North. When it gets warmer than that, deer movement in November is curtailed. But there is still some movement.
When it’s really, really cold, movements will also change. They will get out of the wind, spend time on sunny hillsides (especially those out of the wind), and become more active during the warmest parts of the day. In cold weather during the rut, there may be an exception. In my experience, when a nasty snow storm hits during the night, and the morning temperatures are cold, buck activity can be very good.
Now back to the Texas study. Hellickson also found only a very slightly negative correlation between humidity and movements and no correlation between barometric pressure and movements. Hellickson did not look at time lag, so that might explain these data. But, he also notes, and we agree, that this lack of correlation does not hold for more northerly areas. Cold fronts in the North bring colder temperatures, lower relative humidity and higher barometric pressure. In my experience, and that of most deer hunters, deer activity is high at this time, but drops once the front hits. Then, as things clear after the storm, deer activity really cranks up and you need to be out there.
What about rain? There is almost no scientific data that looks at rain and deer movements and what little there is does not give a strong consensus. Hellickson found that a two-inch rain in September caused increased movements by 70 percent, while a one-inch October rain led to no increase in deer movements. These data are a bit contrary, and other variables may have come into play. Even so, it is obvious that there is much we don’t know about rain and deer movements. My own experience is that a light rain or drizzle is a great time to hunt, especially during the rut.
If rains, even drizzly rains, continue for several days, then deer activity dwindles. And if you get a very heavy rain during the day, but with little wind, deer keep feeding. But if there are high winds, or if the rains are heavy at night, then I believe that buck activity slows considerably. Being a bowhunter, I quit when rains get heavy for several reasons; shooting the bow becomes difficult, and blood trails become non existent. However, right after heavy rains can be a great time to hunt. I believe that at that time deer want to feed, and rutting bucks want to freshen up scrapes.
As opposed to South Texas where weather doesn’t seem to be a major factor in deer movements, in more northerly climates weather is a factor. But there are lots of variables. We all grew up believing that approaching cold fronts stimulate deer to feed. Perhaps this isn’t as much a factor in October, but come cold weather, it does sound logical. It works for humans. When the weather prognosticators predict an approaching snow storm, the local food markets fill up quickly.
The same seems to be true for deer. Most hunters believe a cold snap triggers rut behavior, however, outdoor writer Jeff Murray believes that the cold snap isn’t what causes this movement. Rather the darker conditions from overcast skies followed by a bright sky jump starts the deer. Both ideas make sense.
The Rut; Where Do Those Bucks Go?
In Chapter 8 we discussed the studies done following 15 radio-collared bucks at Chesapeake Farms in Eastern Maryland. The key study was James Tomberlin’s Master’s Thesis done while a student at North Carolina State University. Remember, Tomberlin followed deer in two pre-rut periods (Sep 24-Oct 14, Oct 15-Nov 4), the rut (Nov 5-Nov 25), and the post-rut (Nov 26-Dec 16). The results are interesting to say the least.
We noted in Chapter 8 that some older bucks just pull up stakes and move after the velvet drops from their antlers. They may stay in their new home range a whole year and then return to the original home range. Or they may just come back to visit their original home range. Either way, it explains in part why some bucks you’ve been hunting just up and disappear. It also explains why you may see a big buck on your area, that you have never seen before. The reason? He wasn’t there before and he just moved in.
The Tomberlin study in Maryland spent considerable effort looking at buck movements during the rut. Turns out that all bucks don’t just have one home range. Take “40 orange” for example. This 4 1/2-year-old buck had two home ranges over 1.2 miles apart. In the summer, he lived in one home range, but from Sep 3 to Sep 23, he used both areas. After that he moved to the second home range.
Before Sep 24 “22 blue” (age unknown) lived in one area, but he then shifted and used both his original home range and a new home range 1.7 miles away. But by October 15, his core home range was in the new area, and most of his home range was there as well, but he still spent a little time at the original location. Come the rut (Nov 5) and into the post rut he spent all his time in the new home range. No wonder such bucks are hard to hunt.
Buck “49 blue” (age 3.5 years) didn’t shift home ranges. However, he used two different areas that were 3.7 miles apart. During the summer and also from Nov 26 to Dec 10, he used one area. But during Sept 3-Sep 23 and Oct 15- Nov 25, and after Dec 10, he used both areas. He made purposeful movements from one area to the other on three different occasions. The first was on Sep 7 and he stayed until Sep 23; the second was on Oct 20 and he stayed until Nov 18. His third trip to the other home range was Dec 27 to Dec 29.
Question, do bucks leave their home range for an extensive movement, to areas not previously occupied? The answer to this question is “yes.” Tomblinson’s study is very enlightening on this topic especially since he has pre-rut, rut, post-rut, and winter data.
Table 1. Percent of bucks that leave their home range for an extensive movement. These data are from 15 bucks, all over 2 ½ years of age.
% bucks that move
from their home range day time mvmt. night time mvmt.
Sep 24-Oct 14 13% 0% 100%
Oct 15-Nov 4 40% 30% 70%
Nov 5-Nov 25 58% 73% 27%
Nov 26-Dec 16 20% 30% 70%
Dec 17-Jan 6 17% Unknown Unknown
As you look at Table 1, note that four of the 15 bucks monitored in this study were 5 1/2-years-old, five were 4 ½, two were 3 ½, and four were of unknown age. But all bucks were over 2 ½ years of age. No one has ever published this type of data and it is most interesting and explains why some of the bucks you hunt disappear for a day or more. The reason is that some older bucks leave their home range for excursions into new territory. We can’t tell from this table how often bucks move out of their home range during each time period, we just know that they did leave. For example, during the rut (Nov 5-Nov 25) 58 percent of the bucks left their home range at least once. Some may have left more than once, but we don’t have that information.
The thesis did not specify how long these bucks stayed in the new area, but I believe that most returned within a day. This means you can be hunting an area that you have thoroughly scouted and see a big buck that you have never seen before, and, you may never see him again. Or you can be on a big buck, having seen him three days in a row at the same area, move your stand to that spot, and strike out. He may have moved out for a day, and then return.
Note from Table 1 that as you move from the pre-rut to the rut, more and more bucks take these short-time excursions out of their home range. Then, after the rut, those percentages go down again. The second interesting bit of data here is when the bucks depart their home range. The sample size is small during the Sep 24-Oct 14 period. But in the pre-rut (Oct 15-Nov 4) 70 percent of such movements are at night. Come the rut, 73 percent of such movements are during the day. So in the rut, 58 percent of older bucks move out of your area for a little while (which also means that a bunch of older bucks move into your area from their original home range), and they make many of these excursions during the day. This explains why bucks you’ve never seen pop up under your tree stand during the rut. Then in the post rut, excursions again take place after dark. If you ever needed data to show you why you need to hunt all day during the rut, this is it. And, in fact, these data give you good reason to also spend a lot of time out there before (Oct 15-Nov 4) and after (Nov 26-Dec 16) the rut as 30 percent of their extensive movements occur during the day.
The Moon, Rut Activity and Deer Movements
Here’s a topic that generates discussion and dialogue in every deer camp when there is a full moon. Does it hurt, does it help, are we wasting our time hunting in the day???; the questions go on and on. As you read this section, you will see that there is some science, but there are lots of bits and pieces of a puzzle that are difficult to put together. We’ll present them as best we can, and let you pull out what you need. The real truth, relative to hunting the rut and the affects of the moon on buck movement, is that even though noone knows all the answers, there is a three-week period every year when you just need to be out there, regardless of lunar phases. Let’s be honest. Come the first of November, few hunters look at lunar tables, or the phase of the moon and say, “I’d hunt today, but the lunar tables say that tomorrow is better, so I’ll just site by the fire,”or “I’m not going out today because there is too much moon at night.” They just hunt.
Most wildlife biologists believe that the decreasing amount of day light (compared to darkness) in the fall kicks off rutting behavior. This decreasing light is known as photoperiod. Now if this is what kicks off the rut, then the timing of the rut, i.e. the peak of the rut, will be the same, or roughly so, every fall, because photoperiod is the same every fall.
Although the peak is the same, in some years it may not appear the same because the intensity at the peak can vary. Let’s assume that it is late October and warm. Then a cold snap occurs, and you see an eruption of scrapes and rubs, and some chasing as well. For example, let’s then suppose that come the normal time for the peak, around November 10th or so, the weather warms up, and the amount of rutting activity slows. So, even though the peak of the rut is still November 10th-15th, the low intensity makes it appear that the peak occurred at a different time.
Thus, conventional thinking is that decreasing day length is the key to deer movements due to rutting behavior. However, there are several hunters and outdoor writers who believe that it is the moon in combination with photoperiod that causes the timing of rut to vary each year. These hunters have several ideas as to how the moon affects the timing of the rut.
The idea that the sun and/or moon affects the rut and deer movement is nothing new. There is a very interesting, and somewhat complex, book on natural clocks and natural rhythms in animals. In “Biological Time”, published in 2004, Bernie Taylor discusses how early man used the moon to determine when to hunt. Those beliefs carry over to today. Charles Alsheimer, Jeff Murray, and Dave Morris have written a lot about the moon and the rut. “Google” their names and find several books that go into all of this in great detail
Another truth is that scientific studies don’t give us a consensus on impacts of the moon on buck activity. Some studies have shown no relationship and others show that deer move more at night with a full moon. Space does not permit us to get into great detail on every moon theory, so we’ll just quickly summarize them. For example, Jeff Murray has written about the earth’s gravitational pull, and how moon position impacts the rut. He believes that deer movement is highest when the moon is directly overhead or directly underfoot. We know that deer are most active at dawn and dusk so if you can pinpoint the days of the month when the moon is in either of the aforementioned positions at dawn and dusk, you theoretically have the best days to hunt. Interesting idea, but we do not know of any scientific studies that confirm or reject this theory..
Then there is the moon phase theory promoted by good friend Charles Alsheimer and Wayne Laroche. They believe that the phase of the moon contributes to the influence that photoperiod (amount of day light) has on the rut.
To fully understand this, let’s first list some basic lunar time lines. The first official day of fall (called the autumnal equinox) occurs on September 21. The full moon that is closest to the equinox is known as the “harvest” moon and the next full moon is known as the “hunter’s” moon. Since the moon reflects light it receives from the sun, the position of the moon, the sun, and the earth, cause the cycles of the moon. The new moon (completely dark) occurs when the moon is between the sun and the earth. This prevents light from being reflected, so it is a dark moon. At this time the moon rises at dawn and sets at dusk. Seven days later, we reach the first quarter (half moon). Over the next few days the moon grows and a week later we reach full moon (completely bright). Full moons rise at dusk and set and dawn. Now the cycle goes the other way with a shrinking moon. Seven days after the full moon we reach the last quarter (half moon) when the moon is overhead at sunrise. Seven days later we start the cycle all over again.
Alsheimer and LaRoche believe that the “hunters” moon triggers chasing and that peak breeding begins ten days after the “hunter’s” moon. (usually the “hunter’s” moon occurs in November, but not always). Alsheimer’s book, Hunting Whitetails by the Moon, makes a good case for his theory. Dr. James Kroll also believes that the “hunters” moon cues does to come into estrus and that the peak of the rut will follow the full moon. When you read his most interesting book, Solving The Mysteries of Deer Movement, it does make sense. If you are interested in why deer move, and moon phases, this book is worth reading. Dr. Kroll also showed that the highest daytime activity is seven days from the new moon to the first quarter (half moon). David Morris believes that there is more deer movement during the new moon in early morning and late afternoon. For a full moon he believes that most movement is at night, with some movement spread out over mid day. But he notes one exception. When a full moon coincides with the peak of the rut (2nd-3rd week in much of the northern United States) Morris believes that the rutting behavior is increased, and there is more movement during the day.
Various well known hunters have commented about the above lunar implications and they also have opinions about the many variables that influence deer movements making it hard to pinpoint lunar cycles as the cause. For example, noted deer hunter and outdoor writer Bill Winke, believes that there is merit to Alsheimer’s theory.
The moon rises 50 minutes later each day in the fall and the Drury brothers believe that bucks move more during the time of day when the moon is rising. (You can find out exactly what time the moon rises each day by going to www.stargazing.net/kepler/moonrise.html. .)
Are there data on any of these theories relative to the timing of the rut and deer movement? Yes, there is some anecdotal information and you might check Dr. Kroll’s above-cited book for some interesting data from Texas and Louisiana.
Robert Sheppard is a hunter from Alabama who kept detailed records on deer sightings and moon phase at three hunting lodges and published them in Deer & Deer Hunting magazine. Interestingly, he reported more deer seen during the full moon (5.0 per hunter per day), 3.7 for the new moon, 3.7 for the first quarter, and 3.6 for the last quarter. John Ozoga, biologist working within a one-square mile enclosure in Michigan, has written several articles on deer movements and the rut in his regular column in Deer & Deer Hunting magazine. He compared the breeding dates of deer in his exclosure to the lunar cycles, concluding that there was no affect. Dr. James Kroll found that in northern Louisiana, does had their lowest activity around the full moon and the most activity around the new moon.
Drs. Roseberry and Woolf at Southern Illinois University looked at lunar tables and found no association with buck activity. Researchers at the University of Georgia looked at moon phase and known breeding dates (from captive deer, and by measuring fetuses that can then be back-dated to give the approximate time of conception) from deer in Georgia, Mississippi, South Carolina, Texas, Missouri, Virginia., Maine, Michigan, and Minnesota. They then compared conception dates with lunar phases and with the old method of using a calendar date based on photoperiod and slight weather variables that might influence peak breeding.
For example, they looked at the average breeding date for over one thousand does over a 13-year period in South Carolina and found the average breeding date was October 27, 6.5 days before the “hunter’s” moon. For those one thousand does there was only an average deviation of 4.6 days from October 27. The “hunter’s” moon varies from year to year, so they looked at the average date of conception for individual years and compared that to the time of the “hunter’s” moon and found a deviation of 11.4 days. They concluded that moon phase prediction of peak breeding dates was highly variable, while the tried-and-true calendar date method (i.e. decreasing day length) was much less variable.
The University of Georgia authors believed that “it is not necessary to revise the conventional understanding among deer biologists that mean breeding dates are primarily influenced by photoperiod and are relatively consistent among years within a particular population.”
James Tomberlin’s thesis done in Maryland showed that older bucks were more active and moved around more during the pre-rut when we were in the dark phases of the moon.
Dr. Mickey Hellickson has collected the most hard data on the impacts of the moon on deer movements. As mentioned earlier in this chapter, he put motion-sensitive collars on 43 bucks in South Texas. He categorized deer movements as “inactive” (bedded, standing), or “active” (feeding, walking, running) and followed buck movements 24 hrs a day. He looked at movements during peak rut time from 1999 to 2005 and noted that only 2 of 6 peaks fell within the “hunters” moon predictive period. He then looked at whether bucks move more at night during the full moon as has been speculated by many. He compared movements from 4-5 days of the full moon to 4-5 days around the new moon and looked at two years of data. He found no difference in buck movements.
Dr. Hellickson also compared the amount of day movements for these bucks during full moon vs. new moon and again found no differences. Just a note here. This South Texas data is most interesting and some of the best data ever collected on buck movements. Note though that there was very little hunting pressure in the area studied. Also note that for weather, barometric pressure, etc.—factors that affect deer movements—South Texas is considerably different than the North. Are potential movements dictated by the moon different in South Texas? We don’t know.
The Human Factor. Does Hunting Pressure Cause Deer To Change Movement Patterns?
For years we’ve heard that human hunting pressure causes deer to become more nocturnal. There is no question about this. Humans have a major impact on deer movement. Charlie Alsheimer has looked at deer movements on his New York property and that of his neighbors for many years. Using cameras, he showed that on lands where hunters were using quality deer management, and being very selective in the harvest of bucks (i.e. passing up lots of small bucks), 58 percent of deer activity during the rut occurred in daylight. On lands where there was heavy human activity, lots of hunters, only 32 percent of deer activity was in the day.
Recent new data out of Tennessee was collected on a piece of leased property where there were good buck sightings and harvests for several years, then things went sour. It turns out that hunters had gotten used to hunting certain tree stands over and over, year after year. The good bucks figured that out, so when the hunters moved to other areas on the lease, buck sightings and harvests again came back. The big boys were there all the time; they just figured out human behavior.
Mickey Hellickson and others from the University of Georgia and Texas A&M University at Kingsville had radio collars on 136 males. (This is a different Hellickson study, and yes Mickey Hellickson does a lot of deer research). They observed the behaviors of bedded bucks approached downwind by humans during the day. Locations were mapped for each male around forty minutes after they were chased from their beds. Bucks 2.5-years-old traveled the greatest distance while bucks 4.5 and 9.5-years-old traveled the shortest distances. In general, the older the buck, the less distance they moved when disturbed.
There have been several studies that looked at deer movements before, during, and after a gun hunt and showed the value of good thick cover to keep bucks on your hunting area. One study was conducted on the Fair Hill Natural Resource Management Area in Maryland where there were 134 deer/square mile. Whoa. They obviously need to harvest deer there, so every year 75 hunters per day utilize assigned stands during a two-day hunt.
The problem is that even with this yearly hunt, deer numbers stayed the same, so researchers were looking for a reason. They followed radio-collared deer before, during, and after the hunt. Daytime movement for adult does before the hunt was around 390 yards. During the hunt does moved 430 yards each day, and immediately after the hunt they moved 270 yards. Bucks moved 430 yards a day before the hunt, 325 during the hunt and 780 after the hunt. Peak movement for both sexes occurred at night right after the hunt (does moved 560 yards, bucks moved 1000 yards). Obviously hunting pressure affected deer movements.
Of key interest was the discovery that some deer went to several “refuges” within the Management Area, one being a rather impenetrable (for hunters, not deer) multiflora rose thicket. During and after the hunt a number of deer moved into these refuges. Once in that thick cover, telemetry showed that deer moved about one-third less than deer outside those refuges, especially during the hunt. Thus, they were much less vulnerable to being harvested by hunters. This proves the common sense belief that during hunting season, especially with guns, thick, sanctuary cover will attract, hold and protect bucks (and does) on your property.
Now let’s discuss one more interesting study that shows that deer can be out there, but hunters don’t harvest them because the hunters stay close to roads. It seems obvious that to more efficiently harvest deer, hunters must get away from roads to the rugged, steeper, forested, areas where deer live. But do they? Researchers at Penn State University issued GPS units to follow hunters on a large tract (113,048 acres) of public land. They then interviewed these same hunters. Remember that as they interviewed the hunters to ask where they hunted, the researchers already knew the answers. GPS results showed that hunters don’t get far from roads. While they walked 3.4 miles during the day, they only hunted an average of 0.52 miles from a road. In fact 87% of deer hunters hunted within 0.3 miles of a road. From personal interviews, hunters felt they were hunting over a mile from a road, but the GPS data tell the story.
These data show that there are de facto refuges on public lands simply because hunters don’t get there even when roads are relatively close to such areas. This research leads to the question of whether recreational hunting can be an effective tool for controlling deer on large tracts of public lands that are forested and contain steep terrain. Maybe not. In fact, the authors suggest that in forested ravine habitats in Pennsylvania, deer hunters cannot control the herd. These data tell us that hunters need to move away from roads and get into those inaccessible spots to hunt. The deer are there and the hunters are not.
Food Affects Deer Movement
There is very little hard data to show that food plots, acorn trees, and other feeding areas affect deer movements, but we know they do. Sometimes such movements to and from food are affected by weather and other variables, but the need to feed definitely has a lot to do with deer movements.
Supplemental feed affects deer movements too and Dr. Harry Jacobson of Mississippi State University conducted a research project looking at this topic. He used automatic timers to document activity at feeding stations on the Circle Bar Ranch in Mississippi. They took 14,501 photos of feeding deer and showed what we all suspected...deer feed a lot after dark. (11,036 of the photos taken of feeding deer took place at night.) Deer begin to feed at 6:00 PM, but the peak feeding period was the first two hours after dusk (7:00-9:00 PM). They feed all night long, but have secondary peaks at 11:00 PM and again at 5:00 AM. During the early fall (when we are bowhunting) there is more late morning feeding (6:00-11:00 AM). Can we assume that deer feeding patterns are the same for natural food as for the artificial feed used in this study? Probably so. One last interesting note. Some very large bucks were photographed on this fenced ranch, but were NEVER seen by hunters. The big boys can hide.
Sex Ratios and Habitat Affects Movement
If sex ratios are not balanced, and there are tons of does out there, then the bucks cannot mate all does during one breeding cycle. Thus, 23-26 days later, when the unbred does come into estrus again, we have bucks running around, chasing and tending does. But, via quality deer management, if you harvest larger numbers of does, bringing the sex ratio to a more natural, balanced situation, then more does will be bred within a shorter time period. This means that more fawns will drop in the spring, within a shorter time period and that helps fawn survival (predators can’t get them all since they are dropped around the same time; you won’t get as many late drops and late dropped fawns enter the following winter in lesser condition and have a higher chance of dying).
In essence then, when you get your buck-to-doe ratio in better shape several things happen that makes hunting better. You focus the rut into a shorter time period. This increases the intensity of the peak of the rut, and that means more fighting, more competition for does and more movement. How does this help you, the hunter? More competition for does means that bucks will respond more to rattling, calling, using decoys, etc. Think about it. If you have a ton of does out there, bucks don’t need to come to rattling (where two bucks are fighting over a hot doe or in an area where there is a hot doe). They don’t need to come to calls or decoys. Heck, they don’t even need to come to scrapes, because there are so many hot does around that they just run into them all the time.
It’s true. The more does you have per adult buck, the less rubs and scrapes you will find in that area, simply because competition is not part of the equation.
Also when you kill more does, the habitat tends to improve and this also shortens the rut for the same reasons just cited above. So, for better hunting in the rut, and a whole lot more fun, you definitely want the adult sex ratio to be between 1 doe per buck to 3 does per buck.
Here is something that almost every hunter has observed. In the fall, especially in October, you will see small bucks that you never saw before. You’ve hunted an area fairly hard, think you have all the bucks in the area pegged, then come mid-October, here comes a bunch of new, but small, bucks. What’s that all about?
The answer to this mystery is called “dispersal,” and it occurs every fall when 50-90 percent of all yearling (1 ½-year-old) bucks emigrate out of their birth home range. They depart, and set up living quarters in a whole new area. Some bucks disperse in the spring, but most do so in the month prior to the rut. In my area, that’s October. The distances they move varies with the habitat; the more forests, the less the dispersal distance. In forested areas the average dispersal distance is five miles, though some individuals go much further. In more open farm country the average dispersal distance is closer to fifteen miles. One study done in Illinois showed an average dispersal distance of 25 miles.
A Pennsylvania study showed that in forested areas the bucks dispersed in fairly straight line movements. They leave the area in which they were born and in two hours reach an area where they will spend the rest of their life. However, roads and rivers did seem to be a barrier. Often a new home range was established before a river or a two-lane, paved highway. On the average Pennsylvania dispersing bucks crossed just one paved road. They dispersed to a river or a paved road and stopped there. When bucks disperse they may be subjected to higher mortality as they move into areas that are new to them. Some may be hit by automobiles. Others may lose fights to bigger bucks. Maybe dispersal is meant to happen so that only the strongest survive?
While it is true that young bucks from one property leave, it is also true that the reverse also occurs as others move in. One reality is that the exchange of yearling migrant bucks may not be equal. Your property might be producing bucks with greater antler potential than the bucks that move in. If, for some reason, your area has very high emigration rates and those that move in have lower survival, there can be a net loss of yearling bucks. Yes, there is a lot we do not know about dispersal, but some new research is starting to cast light on this phenomenon.
In recent years there has been an increased emphasis on deer management strategies that include improving habitat, increasing doe harvests and protecting younger bucks. It’s called quality deer management (QDM) and learning why bucks disperse may relate to such strategies (eg. if dispersal is lower, you might keep more of those high-quality younger bucks growing on your property). This leads us to the real question, why do yearling bucks disperse?
It is known that yearling bucks move out, even if the habitat is good. Thus, there are probably social pressures that are the cause. Maybe the mothers drive them out. A 1994 Illinois study showed no differences in dispersal rates for orphaned and non-orphaned male fawns. That might be true for open farm country, but it didn’t hold for Virginia. There, a 1992 study showed that button bucks orphaned before they reached one year of age had much lower dispersal rates than those that stayed with their mother longer than one year. Mothers present, bucks disperse; mothers absent, fewer disperse. Not only that, but orphaned bucks had higher survival rates, probably because they didn’t have to leave their home range. This study then has ramifications for deer management. Remove the mothers via a harvest and you could end up with more bucks on your property. It also suggests that the mothers have something to do with why yearling bucks disperse.
But hold on. Another larger and more recent study done on the eastern shore of Maryland, contradicts this. In this study they observed that bucks orphaned as fawns and non orphaned bucks dispersed at the same rate. (Note, this doesn’t mean the above study was wrong, it just means that we got two different results in two different situations.) The Virginia study suggested that female relatives (including the mother) of the yearling buck drive him away, and in so doing reduce the chance for inbreeding. The Maryland study found that the yearling buck-adult doe aggressive interactions were the same for those bucks that dispersed and those that stayed. From this they concluded that dispersal was not caused by maternal aggression as the earlier research showed.
OK, if it isn’t the mother driving the young bucks away, what is it? The Maryland data showed that before quality deer management (where higher numbers of adult does are harvested, and small-antlered bucks are not harvested) there was an average per year total of 39 emigrants and 31 immigrants. So 39 left while 31 came in; a net loss of eight yearling bucks per year via dispersal. Researchers believe this is because survival of young bucks living outside the area was low due to heavy hunting pressure, leaving fewer deer available to move into the area. After quality deer management (where hunting pressure is greatly reduced) an average of 26 bucks walked away and 37 bucks moved in ... a net gain of eleven bucks. The gain was attributed to the fact that fewer young bucks dispersed from the area. Researchers observed that 70 percent of yearling bucks walked away from their birth areas before quality deer management, while 55 percent did so after quality deer management.
This is a most interesting finding because those who practice quality deer management are interested in having more bucks on their property. And the fact that fewer yearling bucks disperse after a QDM program is implemented keeps more young bucks on your property.
Before finishing up the results of this Maryland study, let me add some other data on the survival of bucks after implementing a QDM program. One logical question is, if I protect yearling bucks from harvest, and they do not disperse, will they die from other causes before reaching age 2 ½? It’s a good question. Dr. Harry Jacobson and his cohorts at Mississippi State University looked at the non-hunting mortality by radio-tracking 238 bucks. They found that natural mortality was low. For example, survivorship for bucks 1.5-2.5 years old was 98 percent (excluding hunting). For bucks 4.5-5.5 it was 87 percent and survival for bucks over 5.5 years of age was 80 percent. Thus, there is no worry in Mississippi that the younger bucks you pass up during hunting season will survive till the next year. Most bucks do survive.
However, James Dozier of Clemson University found higher losses in coastal South Carolina. He conducted research on a 7790 acre hunting lease and the objective was to see how many bucks would still be there for the hunters after three years. Forty-seven bucks were followed for the full three years and over that span, thirty bucks died. Non-harvest factors on the site took twelve (14.7%), hunting on the site took seven (14.9%), off-site hunting took another eleven (23.4%). So, hunters on the lease lost the twelve to non-harvest and the eleven that left the area and were shot. What killed the non-harvested deer? Three were eaten by bobcats, three died from disease, two were poached, one was hit by a car, and three died from unknown causes.
Now back to the reason yearling bucks disperse. The Maryland researchers noted that those bucks that dispersed were involved in more sparring activities with other yearling bucks than those that did not leave their birth places, before and after quality deer management. And they noted less sparring in general after quality deer management. What does this mean?
All young bucks push and shove, and in so doing, they learn who is dominant. However, it’s rare for a young buck to spar with an older buck. Thus, the researchers suggested that dispersal is caused by breeding competition between young bucks. That there is less sparring after quality deer management reflects that there are more old bucks around, and the little guys leave these bigger bucks alone. In addition, the presence of older bucks, reduces the sparring between the yearling bucks. And it is this lower rate of sparring between yearlings that reduces dispersal rates after quality deer management. There you have it. This is probably the reason that yearling bucks disperse ... fighting and sparring with other yearling bucks.
Biologists at the Pennsylvania Cooperative Fish and Wildlife Research Unit also looked at dispersal in two habitats before and after their state-wide antler restriction program. (Note, in essence this is a quality deer management program in that they harvested many more does, and they could not harvest young bucks because of the antler restrictions). Yearling buck dispersal rate was 70 percent in ideal habitat (50% forested), and 44 percent in lesser quality habitat (66% forested). The researchers suggest that when you have more forests, yearling bucks do not disperse as far. During this study increased doe harvests from 2002-2004 lowered overall deer density by 25 percent. The adult doe density decreased by 33 percent, and the sex ratio became more equal. Older bucks (2 ½-years and older) went up 60 percent. Did this change the rate and timing of dispersal? Not as much as in Maryland, but it did change. Before 2002 they found a 40 percent dispersal in the spring and 30 percent in the fall. After increasing doe harvests and antler restrictions yielding more older bucks they found a decrease in the amount of spring dispersal and an increase in the amount of fall dispersal. Overall, the amount of dispersal had a slight drop.
Though these two studies yielded slightly different results, it appears that if you remove more adult does and protect the young bucks on your property, you get more older bucks, less fighting among young bucks, and less dispersal. Thus you will have more bucks. Just another reason to harvest more adult does and let young bucks walk.
Here’s another question. Will yearling bucks that live in an area that has low hunting pressure and do not disperse, survive better than those that disperse? Good question and one 2003 study looked at that. Researchers at the University of Georgia considered ways to reduce the harvest of yearling bucks in order to get more 2 1/2- year-olds in an area. Their approach was simple. Go to a remote 8,400-acre area of West Virginia that has 36 deer per square mile and is heavily hunted. Put a gate up on the only access road forcing hunters to walk into the area. Then put radio collars on yearling deer to see if restricting hunter access reduces harvest.
We know that some yearling bucks leave the area of their birth (disperse), while others do not. The theory behind this study was that bucks that don’t emigrate will survive better than those that do, especially since the gate would probably reduce hunter pressure. They radioed 24 yearling bucks; 15 dispersed off the area, and 9 stayed. The average distance of those that moved was 4.4 miles, but one energetic buck traveled 12.8 miles. That’s a long way in the rough steep terrain of West Virginia. Eleven of the 15 bucks that left their home area were harvested as yearlings, and 3 more were killed the next fall. Of the nine bucks that stayed on the gated area, four were harvested the first year. Only three lived to their second year and two of those were shot in that second year. So, of the 24 yearlings, only two lived beyond two years of age. The conclusion reached was that locking gates in West Virginia (i.e. reducing hunter access), is not the way to get more yearling bucks to survive and grow.
Next question. Since many yearling bucks disperse, can you effectively manage all bucks born on one area throughout their life? Steve Webb and his cohorts at the Caesar Kleberg Wildlife Research Institute in Texas were interested in determining the minimal acreage needed to effectively manage deer. The study was done on a ranch where only mature deer were harvested, and 35% of the bucks on the ranch were at least 5.5 years of age. Sounds like a great place to hunt.
As a part of this study, the researchers looked at dispersal and home ranges of various aged bucks. Sixteen of 24 yearlings (67%) dispersed. Thirteen bucks as yearlings had home ranges that were 1,028 acres. Home range sizes for those same bucks at 5.5 years of age was 56% smaller at 450 acres. Overlap of these home ranges for bucks as yearlings and at 5.5 years was 63%. Mature bucks only move the center of activity of their home ranges by 380 yards per year, indicating little movement from an area once a buck reaches 5.5 years of age.
They also found that 15 percent of bucks dispersed after 2 ½ years of age. One of those bucks dispersed twice before he was 5 ½ years old. Only 10 percent of all bucks radio collared did not disperse from the time they were 1 ½ till they were 5 ½ years of age.
When you consider all the variables that impact deer movement, it tends to boggle the mind. I think that Mickey Hellickson summarized things pretty well when he said that for better hunting success, and understanding the factors that affect deer movement, one should: concentrate your hunting at dawn and dusk, hunt a lot in the rut, stick it out when it rains, and in the northern United States concentrate around the “hunters” moon.
He also makes one other important, but basic, point. Really good bucks probably only make up 5 percent of the deer population, so this makes them hard to hunt. How true that is and that challenge is something hunters have faced since the beginning of time. It is just one of the reasons we love to hunt deer; rain or shine, cold or warm, moon or no moon.
........"This is a chapter of Dr. Samuel's book, Whitetail Advantage, published here with permission of published with permission of Krause Publications, 700 East State Steet, Iowa WI 54990. Copies available at most national bookstore chains such as Barnes and Noble, or at www.knowhunting.com.