April 20, 2023
By Dr. James C. Kroll
I grew up hunting the mixed woodlands and prairies of central Texas, and I shot my first whitetail when I was 15 years old. It was an impressive buck, yet I did not even know how good it was, only that I had taken my first buck. When I was seven, a relative asked me what I wanted to be when I grew up. Without hesitating, I replied, “I want to be a wildlife biologist.”
I never deviated from that dream, and after some 50 years of work, I have fully realized my goal of working with wild animals and their habitats. Graduating first from Baylor University in 1969, with a degree in biology/animal behavior, I completed my training at Texas A&M for a Ph.D. in wildlife biology. At that time, there were no jobs available, so I took a position at a West Virginia college teaching and coaching football.
Since my heart was in Texas, when offered a job at Stephen F. Austin University at Nacogdoches to start a new wildlife management program in 1973, I could not get back to Texas fast enough!
My initial interest and training was in non-game and endangered species research. At that time landowners just were not interested in such esoteric things as endangered animals, so I decided to return to my first love, the whitetailed deer. Believe it or not, at that time, we knew very little about the species, other than the simple basics.
So, I was blessed to begin my work in a world in which almost every discovery was new! At the same time there were about a dozen young biologists, who began their careers at other southern universities. Those were exciting times, and there probably will never be another time when scientists worked so well together, piling up discovery after discovery; and freely sharing knowledge gained.
Colleagues and I in the Southeast Deer Study Group met annually at a different hosting state university to present and argue (a good thing then) over the things that made deer “tick.” The combined work accumulated by this group led to a lion’s share of what we know today about deer biology and management; too often taken for granted by modern professionals and hunters. As a trained naturalist and ecologist, my interests always have been in discovering how ecosystems work. Early on I came to the opinion ecosystems really were landscapes of various elements needed and used by the animals living within them.
Early in my career, I put together my first research plan for the coming 20 years. I always have been a scientist who believes research must be relevant to society, so I decided to call together what today would be called “focus groups” of hunters, landowners, foresters and wildlife professionals. My question to these groups was simple and to the point: What do we need to know about white-tailed deer? The first answer came in the form of a question: “What can we plant for deer?” Then came in succession: “Why can’t we kill them?”
Our plan took on many solidly defined goals, based on these first two questions. As our work proceeded into the second and third 20-year plans, dozens of new questions emerged. I am a firm believer that, a good scientist defines a question, puts together a plan to answer it, and lets the work take him wherever it goes!
PLANTING FOR WHITETAILS
When we began our work, Texas ranchers often planted cereal grains for winter grazing of cattle. Since they noticed deer showed up often to enjoy the oat and wheat fields, planting “oat plots” for whitetails became a common practice.
Yet, it seemed as if heaven forbid you put much effort into the plot! Most hunters were convinced all you needed to do was throw some oats on a patch of ground and wait for rain. In those days, hunters practiced what we called 50-50 food plot management — 50 pounds per acre of feed oats and 50 pounds of 13-13-13 fertilizer. We needed a better approach, so I went to the folks who knew most about planting forages for ruminants — dairymen! When asked about what forages would work best for deer, dairymen always answered cereal grains and legumes. Given this information, we began what became the longest running research program on deer food plots in history. Over the years, we tested every plant variety that could possibly serve as a good deer forage.
By the 1980s, we had focused in on the best candidates, and were well into field trials on each, alone and in combination with others. Several of my graduate students contributed significantly to this work, but none more than Dr. Billy Higginbotham, who recently retired as wildlife specialist for Texas A&M University Agricultural Research and Extension.
Billy was the one who fully tested each of the cereal grains, most of the red and white clovers, and even several varieties of cowpeas and soybeans. Together, we came up with the idea, that there really were two types of food plots: warm season and cool season.
We also discovered that whitetails have two stress periods — late winter and late summer. To improve the diets of deer, we would have to develop geographically targeted plant species and varieties that would do best under the harsh climatic conditions imposed by these times of the year. We also had to focus on site conditions, such as soil type and topographic location, and find plants that do best in these locations.
WHY CAN'T WE KILL THEM?
What the hunters really were asking was: Why can’t I find a trophy buck and kill him where I hunt? To answer the question, we began what became over 20 years of studying deer movements using radiotelemetry collars. Our research taught us so much, especially about the whitetail’s preferred habitat.
In those days, you could not easily buy radiotelemetry collars; you had to make them yourself or find someone who could. My early work with designing radios for studying snake movements gave me the experience to begin R&D on radiotelemetry of deer. Other colleagues in the East were also doing similar work, and again we shared information. Drs. Harry Jacobson, David Guynn and Larry Marchinton were deeply involved in behavior studies in Mississippi and Georgia; and produced a wealth of information about deer movements.
What we discovered sounds simple, but it was amazing at the time. Radiotelemetry proved hunters were having trouble killing mature bucks, because they were not hunting where the bucks lived nor when they moved! I focused my work on the individuals of greatest interest to hunters — mature bucks.
In those days, eastern Texas had an average deer density of around one deer per 40 acres and one mature buck to 600 acres. That is why the early telemetry studies involved immature bucks, which did not provide the right answers. I began capture efforts with a new technology, the tranquilizer gun. My adventures were many, but safe to say the first mature buck I captured took 1,200 hours of sitting in trees! As time passed, I got better at it, and capture technology was evolving. Tranquilizer guns led to rocket nets, which then led to drive nets, and finally (thanks to the New Zealand deer capture techniques) the netgun and helicopter.
Throughout my travels, I learned that wildlife habitat is really a landscape made up of critical elements in the right locations. It turned out there really were only three critical habitat elements: food, cover and water. Food is perhaps the most interesting habitat element among hunters. Deer food can be further divided into forage, mushrooms and mast (fruits and nuts of trees and shrubs).
Since a whitetail is only about four feet at the shoulder, we learned that there was a “deer zone,” in which forage must be available year-round. Everything a deer needs to eat must exist in the deer zone; even acorns which fall into it! As a forester, I spent a lot of time studying deer forage in woodland habitats, especially as clear-cutting practices were widespread in the 1970s and 80s. I learned that deer inhabiting forested areas spent most of the non-rut time of the year in about 80 acres, provided all critical habitat elements, including water, were present.
In the context of the 80-acre landscape, there must be a perennial water source in each management unit. This can be in the form of a stream, water hole or pond. Deer do not like running water, preferring to drink from a cow track than a clear water stream! This led to our research on artificial water sources, which have become so popular in recent times.
Since new forage could only be produced by clearing or thinning the forest, we devised “rotation” ages of stands intended for deer forage. In the South, plants quickly grow out of the deer zone in 5-7 years, so you must make cuttings on that cycle. In the North, the cycle increases to 12-15 years, due to slower plant growth. Of course, these are generalities, and each area can be different. Deer management is site-specific.
The same holds true for minimum whitetail home ranges in various parts of the country. Later, we learned that the 80-acre management unit did not apply universally. In climatically limited areas such as grasslands, deserts and brushlands, the minimum area may be much larger; 160-640 acres. Understanding deer cover turned out to be a bit more complicated. There are at least three types of cover: winter, summer, screening and edge. Winter thermal cover is composed of trees or shrubs that have a relatively tight canopy to protect from rain and snow, yet also having a dense understory to impede the flow of cold winds. Summer thermal cover is quite different; it is composed of a lightly stocked overstory, producing dabbled shade with very little understory to impede wind movement.
Escape cover cannot be quantified as easily as the thermal covers, since it can be any area that allows a deer to run a short distance from a threat (predators and humans), stop to survey the situation, and yet not be seen. Screening cover must be dense horizontally, not vertically.
A NEW DIRECTION?
As my first 10 years as a biologist passed, I had become increasingly frustrated by the lag time between finding something out and it being implemented by hunters and landowners. We were making lots of discoveries alright, but the public was unaware of them. That is where I think God stepped in!
I had just returned from one of the Southeast Deer Study Group meetings when my wife called out to me. “There is a fellow on the phone wanting to talk to you,” she said. When I answered the phone a man with a distinct southern drawl introduced himself as David Morris, and he said he was at the Study Group meeting and was impressed with my work. Then he made a proposal that changed my life forever. “We have put together a magazine called North American Whitetail that is devoted solely to the species,” said David, “and we were wondering if you will be willing to write for us?”
Flattered, I explained that I was a scientific writer, not a popular writer. David then said something that sold me on the idea. “There are lots of great outdoor journalists,” he said. “But they are not good hunters! We want to take great deer hunters and managers and make good writers out of them.”
In the late 1980s, we began work on a demonstration area that would serve as a proving ground for all these concepts. Steve Vaughn, managing partner for Game & Fish Publications (parent magazine of NAW), had purchased land near Fort Perry, Georgia, and wanted to implement our findings as a demonstration area for the magazine. I was glad to join in the project, and it is Fort Perry where much of the tried-and-true principles of deer habitat management were fine-tuned.
Later, we held a meeting at Fort Perry in the early 1990s to develop a more effective way to extend our findings to the public. Editor Gordon Whittington, David, Steve and I were in attendance. That’s where we came up with the idea of “Building Your Own Deer Factory.” First as a new magazine department, and later as a segment on NAW TV, it became one of our most popular offerings. After almost 20 years, I had found a way to get the latest information about deer habitat and management to the public.
I am proud of the contributions we made to modern whitetail management, but we certainly were not alone. While we were conducting our studies, the dozen or so young biologists — many of whom now are either retired or deceased — were contributing equally to our knowledge of whitetails. I hope this article gives you an appreciation of the institutional history of whitetail management and hunting. Everything we know came from hard work, creative thought and unselfish sharing of information by scientists dedicated to the animals we love.