Part 9: Predator Induced Stress

Last week I shared with you a summary of Dr. John Kilgo’s long-term research about the amount of fawn mortality primarily caused by coyotes to deer in South Carolina. The results were that 70% of the fawns were killed by predators before the first hunting season after they were born. At that rate of mortality, even without any harvest by hunters, deer populations will decrease. This problem is not everywhere yet. However the number of coyotes, bobcats, black bears, cougars/mountain lions, etc., is increasing rapidly in many areas.

Several of my fellow researchers besides Dr. Kilgo have reported similar findings of predator caused mortality on young deer and even adult deer. Predators are a significant factor on deer populations in many areas!

Whitetail deer are prey for predators

However, direct mortality is only part of the picture. Even healthy adult deer that are not as susceptible to being killed by predators still can suffer because of high predator populations. Great research on elk in Yellowstone National Park has shown that elk that haven’t been killed by wolves are averaging fewer calves per cow, lower body weights, and the males have smaller antlers on average than before wolves were reintroduced. How can this be? Fewer mouths competing for the same or more food should result in more calves per cow, heavier body weights, and larger antler for each age class.

The answer was found by comparing the levels of specific hormones in elk before they were exposed to wolves and then again five years after wolves had been released into Yellowstone. These hormones are produced and released in critters that are stressed. The levels of these hormones were several times higher in the elk after being exposed to wolves!

This is not surprising. The medical news is full of studies reporting how damaging stress is to human health. Dairy, beef, and even poultry farmers attempt to reduce stress in their stock so they will be more productive. The same is true with game animals. Being chased or even living where they need to be constantly vigilant to avoid predators results in increased stress.

Increases in the number of predator populations (increasing coyote, bobcat, bear, hog, etc.) certainly results in increased stress for several species of game animals.

In addition to reduced health caused by predator induced stress, there is another negative to allowing the predator population to increase significantly.

Deer and turkeys that are constantly vigilant against four-legged predators are also constantly vigilant against two-legged predators. It will likely be more difficult to observe game species on properties that have an abundance of coyotes and other predators. I’ve worked on a few properties that had an abundance of predators. We called and trapped to reduce the number of predators and the observation rate of mature whitetail bucks increased within weeks! These bucks didn’t mature into the population. It is doubtful they moved into the population. They simply became less vigilant.

To have more mature bucks to hunt, there must be more fawns recruited into the population. It’s noticeably easier to have encounters with mature bucks when they are less vigilant. Significantly reducing the number of predators will likely have a positive impact on deer herds. Due to increasing predator populations and decreasing numbers of trappers, predator management is rapidly becoming a significant part of deer and turkey management.

Growing Deer together,

Grant

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Part 8: Predators

The past seven entries for this blog have been on the subject of managing for and killing mature bucks. However, in recent years just following the play book for passing bucks and providing quality food, cover, and water may not yield the results you desire. Something has changed across much of the landscape.

It’s the number of predators. When I was a boy (I was born in 1961), coyotes were shot on sight by farmers (almost every farmer I knew always had a rifle in his truck). Raccoon pelts were bringing $50.00 +/- and anyone I knew that was any kind of hunter or outdoorsmen trapped and/or hunted raccoons as a source of additional income. Chicken hawks (any large hawk was called a chicken hawk) were also shot on sight. These actions didn’t cause any of these predators to go extinct.

I went off to college and was taught to feel sorry for predators. I was taught that predators were almost never an issue with game species. That might have been true then (although I had a hard time buying into the theory). I was also taught in college that all natural systems are very dynamic – always changing (I certainly have experienced and agree with that!). Whatever the theories and realities were, the current impact of predators on deer, turkey, quail and other game species are real and measureable!

This last statement is not simply my observations. I had a graduate student five years ago study the impacts of coyote and bobcats on fawn recruitment (fawns surviving until hunting season) on a private property in northern Alabama. Briefly summarized, the results were stunning! He monitored fawn recruitment during year one, then had a trapper remove many coyotes and bobcats from the 2,000 acre property during the following fawning season. During the second fawning season there was a 150+% increase in fawns at the same property as result of removing 20+ coyotes and 10 bobcats! It appeared the turkey and rabbit population also exploded!

35th Annual Southeast Deer Study Group

When Cory VanGilder (the grad student) presented his results at the annual Southeast Deer Study Group Meeting, there wasn’t much excitement among the 100’s of scientists in attendance. Fast forward five years, I just returned from the 35th Southeast Deer Study Group Meeting. Just to give you a hint of the change in attitudes among some of my fellow deer biologists, the theme of the meeting this year was Shifting Paradigms: Are Predators Changing the Dynamics of Managing Deer in the Southeast? Twelve of the 35 presentations were on the subject of coyote predation on deer!

Several of the researchers reported results of fawn mortality documented by the use of vaginal transmitters (VITS). This technology allowed researchers to captures does after they’ve been bred and insert a transmitter in their vagina. The VIT is pushed out of the birth canal when the fawn is born and alerts the researchers by changing the frequency/tone of signal. Researchers can often find the birth site and/or fawn within four hours or less after birth.

Dr. John Kilgo, a talented researcher for the Forest Service, has years of such data. He and his staff have documented that in recent years, 70% of the fawns were killed by predators at their research site (a 300 square mile area in South Carolina) during the first few months after birth! 62% of the total mortality was due to coyotes!! This is not a guess or a theory. At this level of predation, even without any hunting mortality, deer populations will decrease rapidly in number and quality (more on the stress of predation next week).

John and his staff swab the kill site and use advanced techniques with genetic testing to confirm if the killer was a coyote, bobcat, domestic dog, etc. Using this technology, they can tell if it was a male or female predator, and if it was the same predator that killed a fawn ¼ mile or 10 miles way. John’s research is fascinating!

He ended his abstract by saying “I predict that this pressure (coyotes) will require significant changes in how deer populations are managed in the Southeast in the future, because coyotes are here to stay.”

I agree with John, but know from my student’s work and my experience that coyotes can be trapped and their impact on deer populations reduced. Trapping and calling coyotes are fun activities (GDTV 119). However, it requires time and effort. There is no easy method to significantly reduce coyote populations. Some managers will simply let their deer herds be significantly reduced by coyotes. I, and hopefully many others, will not sit by and watch deer populations be reduced significantly by predators. I will actively call and trap coyotes to keep their population in check so deer, turkey, and other game species can maintain a healthy population.

I enjoy hearing a coyote howl. However, I enjoy seeing and interacting with deer and turkeys more. When push comes to shove, I’ll be the deer’s best friend and the coyote’s worst enemy. How about you? Will you sit by and watch America’s favorite game species be reduced to the occasional rare sighting? Or will you join me in protecting the future of hunting?

The damage by coyotes and other predators to deer and other game species is not just direct mortality. Predators also can cause much stress to game species! Next week I’ll share more about this issue.

Growing (and protecting) Deer together,

Grant

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Part 7: Flat Ground – The Huntable Side

Last week I shared the advantages of flat ground to produce mature bucks. That discussion was more about the ability to produce quality forage, and therefore quality bucks (if they are allowed to mature). There is another substantial advantage to flat ground. It may be the best reason to seek a hunting property that is flat versus steep.

Hunting flat ground has advantages for predictable wind direction and easier crop production

The huge advantage of hunting flat ground is that the wind seldom swirls where the topography is flat. The wind does change directions as fronts pass, etc., but it rarely swirls and certainly doesn’t swirl on a constant basis. Swirling winds are often caused by changes in topography. Changes in topography create eddies where the wind sinks and rises. Rapid changes of topography also create temperature gradients (warm air rises and cool air sinks). These temperature gradients cause thermals or air moving based on slope and temperature.

Deer move the most during dawn and dusk. There is more air movement due to thermals during these same time periods because this is when the temperature is changing the most. It may well be that in areas with steep topography, deer are the most active during dawn and dusk to take advantage of the swirling winds to aid their avoiding predators (2 and 4 legged). Swirling winds and thermals allow deer to detect predators from multiple directions – not just one (like what would occur in areas where the wind is typically out of one direction).

There can be some thermal action in flat country. However, the direction and duration of the thermals seem to be much more predictable compared to areas with steep topography.

Most hunters throughout the whitetails’ range are blessed enough to have access to hunt flat ground. My property is the opposite of flat. In fact, it changes elevation 350+ feet several times due to the ridges and creeks. To reduce the chance of being detected by a buck’s nose, I use a complete system of cleaning my gear and good personal hygiene, including doing laundry for better deer hunting. I use the natural Dead Down Wind products as they eliminate a wider spectrum of odors than most of the products that are created to only reduce odors created by bacteria. I also want to reduce odors on my gear and myself from lubricants and whatever else might alert bucks.

There are several advantages to hunting flat ground. These advantages include producing better quality forage so bucks can express more of their potential and being able to predict the prevailing wind direction while having fewer thermals. These are two huge advantages to any deer hunter.

Growing Deer together,

Grant

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Part 6: Flat Ground

I’ve been discussing how to manage land to produce mature and huntable bucks. It’s relatively easy to produce mature bucks. Simply don’t harvest them until they are 4+ years of age. I define mature for whitetail bucks as being four years old or older because by that age most bucks have expressed 90+% of their antler growth potential.

Food plot with a utilization cage

In this blog series I’ve also discussed management strategies which allow bucks to express their antler growth potential. Just because a buck is allowed to live until he is 4+ years of age doesn’t mean he will produce antlers to his full genetic potential. If he hasn’t had access to a quality diet throughout his life and experienced minimal stress, he will not produce antlers as large as his genetic potential.

Now that we discussed several aspects of managing deer so they can express their full genetic potential, I’d like to discuss how to harvest mature bucks. Last week I shared that I’d found several sheds in bottlenecks or pinch points while laying out a habitat management plan on a property in central Missouri.

I really enjoy finding sheds. However, finding where a mature buck has been is not the same as being where a mature buck is – within shooting range! Predicting where a mature buck will be during daylight hours and being there at the same time – especially accomplishing this on a year after year basis – requires a lot of skill and preparation.

Wonder why so many whitetail hunters go to areas that produce commercial row crops year after year? If you look at a map of the whitetail’s range, the portion of the area that produces commercial row crops is a relatively small portion of the whitetails range. Yet, the majority of Boone and Crocket and Pope and Young entries come from the areas where commercial crops are produced.

There are two simple reasons and they both relate to flat ground. Flat ground – especially in the Midwest is almost always better quality soil compared to where the topography is steep and the topsoil has been eroded. However, years and years of producing and harvesting commercial crops have significantly reduced the amount of nutrients and beneficial bacteria in the soil. Without adding fertilizer and beneficial microbes back to the soil, it would not be nearly as productive. These elements are rarely added back to the soil unless it is commercially farmed. Hence they are rarely applied to areas with steep topography.

My property, The Proving Grounds, is a perfect example. It has very steep terrain and was extremely eroded from exceedingly poor timber harvest and agricultural practices decades ago. There literally was no topsoil only rock – literally – only rock. I never disk a plot at my place because it would only shuffle rocks around and cause erosion of the limited amount of organic matter that is present.

However, by adding poultry litter that has been composted with beneficial, soil building bacteria added (Antler Dirt) I’ve significantly improved the quality of crops produced in my food plots. I can now grow quality crops, even on the rocky soil where I never disk! Remember that quality forage and grain crops are only nutrient transfer agents. They serve to transfer nutrients from the soil and air (air is roughly 78% nitrogen – capture that and never pay for nitrogen again!) and transfer those nutrients to deer and other plant consumers.

Some plants are better at capturing nutrients and transferring to consumers (deer, cattle, humans) than others. Those plants typically are the crops grown in commercial ag – to feed humans (and deer). Oak trees transfer nutrients – but the vast majority of the nutrients they transfer are tied up in the wood or the structure of the tree.

Soybeans also transfer nutrients but a much higher percentage of the nutrients they transfer from the soil and air are deposited in the soybean leaves and eventually the soybean pods. Deer readily consume soybean leaves and pods. Deer rarely consume the trunks of oak trees – and never express their full antler growth potential when oak leaves and acorns are most of their diet. This is a primary reason bucks of the same age class living where soybeans are commonly grown will have larger antlers compared to bucks living in areas that are primarily forested.

Some of you are already yelling “acorns.” Acorns are much lower in nutrient content than soybean leaves or pods – there is no comparison between the nutritional quality of acorns and soybeans – or the antlers produced by bucks that primarily consume either crop.

So, if you want to hunt mature deer that have expressed most of their antler growth potential, you need to hunt where the soil has plenty of nutrients and plants that efficiently transfer those nutrients from the soil and air to deer. This can be in regions were commercial crops are grown (flat land), or where quality food plots are maintained.

For example, there isn’t a commercial soybean or corn field for many miles from my property (The Proving Grounds). However, over the years, I’ve converted the few flat spots among the hills where I live to well fertilized food plots and usually plant Eagle Seed forage soybeans. The results have been more than pleasing! My family and I have been blessed to produce and harvest several large, mature bucks.

If your objective is to harvest mature bucks with large antlers, you can go to flat, crop producing ground, or grow the same crops where you hunt. Big antlers start in the dirt – and it usually requires well fertilized flat dirt to grow good nutrient transfer agents (crops like soybeans) to allow bucks to produce their best antlers!

There is another HUGE advantage to managing and hunting deer where the land is flat. I’ll discuss that next week.

Growing Deer together,

Grant

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