It was only one o’clock in the afternoon, yet several deer were already feeding in the field. Seeing this unusual phenomenon I turned to my son and said, “It’s going to storm!”
Whitetail have an innate sense for knowing when bad weather is approaching. A couple of days before the weatherman predicts a drastic change in the forecast—based upon radar and weather models—deer already know. But how?
If you’ve spent any amount of time watching whitetail, you’ve seen how deer respond to an approaching rainstorm or snowstorm. Whitetails are often seen feeding days in advance of a change in weather. And those well-versed in whitetail behavior believe deer are simply responding to a change in barometric pressure.
Barometric pressure, also known as atmospheric pressure, refers to the amount of air pressure exerted by air molecules against the earth’s surface. Combining the force of gravity with literally miles of air molecules equals approximately 14.7 pounds per square inch of pressure at sea level. It’s the increase or decrease of this pressure that is known to affect animal behavior.
Meteorologists often talk of either ‘low-pressure systems’ or ‘high-pressure systems’ when referring to the weather. These terms simply refer to increased or decreased barometric pressure within a weather system.
If the air molecules above the earth’s surface are not as compressed, the result will be a decrease in barometric pressure. The resulting low-pressure system is known to usher in clouds, rain and/or snow.
After adverse weather moves beyond an area there will be an increase in the compression of air molecules, which in turn causes the barometric pressure to rise. A high-pressure system is often characterized by a combination of clear skies and windy or breezy conditions.
Warm And Cold
Another interesting fact concerning low-pressure areas is how they produce the weather surrounding the advancing storm. The counterclockwise circulation of a low-pressure area will result in cold air forming to the north and west, while warm air is formed on the south and east.
This explains why colder winds and temperatures can accompany a north or west wind. Remember this tip when checking barometric pressure and wind direction prior to a hunt.
Barometric Pressure And The Bowhunter
Whitetail are very in tune to changes in barometric pressure and the resulting atmospheric conditions. Deer will bed, feed and move according to if the barometer is ‘rising,’ ‘steady’ or ‘falling.’
Most hunters who have made a study of barometric pressure and how it corresponds with whitetail behavior, believe whitetail are more active when the barometer is either rising or falling and most active when the barometer is rising. My personal preference is to hunt a rising barometer immediately following a storm. I generally see more deer movement following a hard rain or right after a blizzard.
These observations also suggest deer activity is best when the barometer is 29.90 or higher. Ideal conditions are when the barometer is close to 30.0 inches, is rising and has nearly peaked. This is a recipe that usually results in increased deer movement—especially in bucks.
It would seem from collective observation, when the barometer is falling deer anticipate the possibility of weather impeding their ability to feed. This results in more aggressive whitetail movement as deer attempt to feed for preventative measure.
When weather such as a snowstorm or rainstorm is about to subside and the barometric pressure begins to rise, deer will again feed actively due to their lack of eating while they waited out the severe weather. While not comprehensive, hopefully this practical application will give you an idea as to how whitetail respond to changes in pressure and a few reasons why.
A whitetail’s response to barometric pressure gives the bowhunter insight into knowing how to plan the next hunt. With numerous weather related websites and weather apps to keep us informed, our chances of being where we need to be when we need to be there should also be on the rise.
While the barometric pressure is only one contributing factor to deer movement, it is an important element that should not be overlooked. With fall weather already upon us, use the barometer to your advantage.
If you have any additional tips or would like to share how you use barometric pressure when planning a hunt, please feel free to comment below.