While sitting in my tree stand, freezing my tail off and not seeing any deer, I have often wondered where the deer were and what they were doing. Yeah, I used to be one of those crazy idiots who went out in subfreezing weather dressed like the Pillsbury Dough Boy (six layers of clothing and a white suit) and sat in my stand with the wind howling around me, questioning my own sanity, but not any more. Maybe I have gotten smarter over the years or maybe I have just gotten too old. Either way, when the temperatures drop, the dewpoint lowers and the wind picks up, I don't get up early to go sit in my tree stand. Oh, I still hunt, I just don't sit in my tree stand. I still-hunt, especially if I've previously patterned the deer and know where to find them.
I have always been fascinated by animal behavior, and went to college to become a wildlife biologist, then quit to become a professional hunting guide. After ten years I quit guiding so I could return to my first love, wildlife research. Since 1994 I have spent hundreds of hours correlating deer movement with weather conditions, so that I wouldn't have to sit in my deer stand looking like Frosty the Snowman.
During my study I noted the light conditions, time, sunrise, sunset, temperature, wind-chill, dewpoint, wind speed, wind direction, precipitation, and barometric pressure. I placed my data on a graph and kept notes on when and where the deer where, what sex, which deer they were, what direction they were traveling and what they were doing. Several other researchers have studied many of the individual factors that I did, including temperature and dewpoint. But, my study differs from theirs, because I considered all the known factors I could think of. The results of my study concur with most of the other researchers. I found that the factors that affect fall deer movement are: Comfort, Security, Predatory Behavior, Food, Breeding, Distance, and Lunar.
During my studies I found what I believe to be the predominant meteorological factor that determines daytime deer movement in the fall; wind-chill. Wind-chill factors can cause both a decrease and an increase in daytime deer movement because it affects their comfort. Comfort factors are so powerful that they override most of the other factors that influence fall daily deer movement, including lunar forces and the rut.
Deer feel temperature the same way humans do. When it's hot we feel uncomfortable, when it's hot and humid (making the dewpoint high) we feel even more uncomfortable. When it's hot or the dewpoint is high and there is a strong wind we don't feel as uncomfortable. When it's cold we feel uncomfortable, when it's cold and damp creating a low dewpoint we feel more uncomfortable, when it's cold, damp and windy (creating low wind-chills) we feel very uncomfortable.
Like humans deer have preferred temperature, dewpoint, wind-chill and wind speeds in which they move. These are the Comfort Factors which influence daily deer activity. Once deer grow their winter coats in the fall high temperatures keep them from traveling very far in daylight hours. They usually wait until the sun goes down and temperatures drop before moving. When temperatures are low deer often stay in areas providing protection from the wind, move to areas open to the sun or wait until the daytime temperatures rise, then move during daylight hours, especially when cloud cover is present.
My studies and those of Dr. Ken "Doc" Nordberg both took place in Minnesota and the flexible parameters given should apply to whitetails in the northern half of the United States and Canada. I stress the word flexible because deer in different areas have different tolerances. Data from Texas suggests that southern deer are more tolerant of high temperatures, and because they are not subjected to the extreme cold of the north they are probably less tolerant of low temperatures. During his rattling study in Texas Mickey Hellickson found that bucks responded best to rattling when temperatures were between 70 and 80 degrees. Deer in other areas may have different comfort range tolerances. Even individual deer have different tolerances. Bucks, especially during the rut, will move in almost any weather in search of estrous does.
When I charted deer sightings according to temperature it became evident that the majority of the movement occurred between 10 and 55 degrees. Most of the deer sightings occurred between an hour before and an hour after dawn and dusk as expected. When the temperatures dropped the morning deer sightings occurred from sunrise to an hour and a half after sunrise, with minimal pre-sunrise movement. The evening deer sightings occurred from an hour and a half before sunset until an hour after, with several deer sighted after sunset. As the temperatures dropped below 20 degrees the deer continued to move later in the morning, but there were fewer sightings, while afternoon sightings actually increased.
