PRECIPITATION AND ITS EFFECTS ON WHITETAIL DEER MOVEMENT
by Darrin Bradley
A screaming alarm clock sounded off at 4:30 AM on a Saturday morning in 1994. As I climbed out of a warm bed I stumbled over to the window. Discovering it was raining, a slight grin broke out across my face, as I realized I was only moments from climbing back into the relaxing confines of the bed for some additional sleep. My last waking thought was, “I’ll sleep late, and maybe bowhunt this afternoon if it’s not raining.” As mid morning arrived, I awoke again and drove to the local archery shop. The rain continued to fall. I planned on having some minor work done on my weapon and maybe shooting some 3D targets. “If the rain stops, I’ll go bowhunting this evening,” I thought to myself. Venturing into the Archery shop I began looking for my favorite assistant to work on my bow. Stepping up to the counter, I requested a conference with Rick. The owner of the shop annoyingly stated, “Rick isn’t here today. He always calls in sick when it rains so he can go bowhunting. How can I help you?” This scenario was my first clue I was missing out on some quality whitetail hunting, and I needed to learn more about whitetail behavior. Had there been a side to deerhunting I overlooked? Had I discovered why I was not being successful in harvesting mature whitetail bucks? One possibility was that Rick was simply insane. However, Rick had harvested a number of mature bucks. This evidence was enough to negate any questions I had in regard to Rick’s sanity. I had been wrong all along. The key to deerhunting is understanding whitetail behavior. It was on that day I began recording and observing whitetail behavior during hunts. It was then I began traveling down the road to success.
I must define the terminology by which I have measured whitetail movement. A “successful hunt” is defined as a hunt in which I view whitetails from a stand location. An “unsuccessful hunt” is defined as a hunt in which I do not view whitetails from a stand location. A “win/loss record” is defined as the number of successful hunts in relationship to the number of unsuccessful hunts. For example: If I participate in five hunts and I am successful on three of those hunts, I possess a win/loss record of 3 2. This is much like a professional sports team win/loss record. A “success percentage” measures the percentage of successful hunts I participate in. For example: If I hunt ten times and am successful on six of those hunts I possess a success percentage of sixty
percent. A “passed shot” is defined as anytime I refuse to shoot an animal within bowrange from a stand location. This practice is performed to pass up on inferior animals in an attempt to selectively harvest mature bucks. These five terms will be referred to throughout the series for measuring success and whitetail movement.
I have recorded environmental conditions on 433 separate hunts since 7/30/94. During this period of time, I was “successful” on 304 hunts. I was “unsuccessful” on 129 hunts. The “win/loss” record of 304 129 results in a 70% success percentage.” This career success percentage will serve as the standard by which whitetail deer movement in precipitation will be measured. To simplify, any success percentage lower than 70% will be viewed as inferior in relation to my hunting abilities. Any success percentage higher than 70% will be viewed as superior in relation to my hunting abilities.
The data collected for this study was collected from Northeastern Missouri and Western Illinois. In this area I have collected data surrounding four separate types of precipitation. These are inclusive of rain, approaching storm fronts, sleet, and snow. Of the 433 hunts recorded, ninety nine of them occurred in active precipitation. These active precipitation hunts produced the following results:
Win/Loss Record Success Increased Deer Movement
1. Rain (29 hunts) 23 6 79% 9%
2. Snow (11 hunts) 6 5 55% 15%
3. Sleet (2 hunts) 2 0 100% 30%
4. Oncoming Storm Fronts (57 hunts) 47 10 82% 12%
It appears precipitation increases whitetail movement. During the rain whitetail movement increased by 9%. Whitetail movement during sleet increased by 30%. Approaching storm fronts increased whitetail movement by 12%. Curiously, whitetail movement decreased deer activity by 15%. I propose that whitetails are more apt to remain in the safety of the sheltered bed areas during a snow. I could elaborate and make an educated guess as to why snowstorms decrease deer activity however I have learned that sometimes I do not need to know why deer react in the manner that they do. I simply need to know how they react and adjust my hunting strategy accordingly. Due to the apparent decrease in whitetail activity during a snowstorm, I will hunt close to bed areas as deer are not traveling to and from the foodsource as frequently. The bottomline is one needs to understand whitetail behavior during precipitation, and make the necessary strategical adjustments to become successful.
I frequently harvest does in an attempt to manage the herd and reduce crop damage for the landowners who permit me to hunt. I believe any deer harvested with a bow is a trophy; however I live for big antlers. The aforementioned study depicts all deer movement stimulated by precipitation. Precipitation effects mature whitetail buck movement specifically. Over the course of 433 hunts, I have viewed 56 bucks which would possess a Boone and Crockett score exceeding 130 inches, National Record Book Bucks. Twenty two (39%) of the fifty six Pope and Young bucks seen were viewed during hunts involving active precipitation. Interestingly enough , only 22% of all my hunts recorded occurred in active precipitation. One must calculate the number of Pope and Young animals that would be seen if the number of active precipitation hunts were equal to the number of non precipitation hunts. After completion of this task I amazingly discovered Pope and Young buck movement more than doubles during active precipitation.
In November of 1998, I took to the field during a downpour for the afternoon hunt. My hunting companions refused to accompany me in the cold November rain. During that cold, lonely evening hunt I placed myself within bowrange of two separate mature bucks. I selected one of the animals for harvest and found myself at the taxidermist shop the following morning. I know now why Rick was so passionate about calling in sick to work on rainy days during bowseason.