Before you’ll ever be able to take advantage of topographic features that deer relate to, you’ll have to first understand how wind relates to these features. I think it’s safe to say that wind is one of those topics that you can never seem to get away from, no matter if you’re hunting the grassy plains of Nebraska, the brushy draws of Illinois or the rolling hills of Tennessee. The wind dictates so much of what we do as hunters, so naturally it has become one of the most important factors that we must consider when planning a hunt. But does the typical quick analysis of prevailing wind direction cut it in all situations? I think it’s safe to say no, it does not. Most of us know how to hunt a given wind, but when hunting in any kind of hilly country, wind acts in strange and finicky ways that can both make or break a hunt. In our journey to better understand how to use terrain to improve our deer hunting success, let us first take a look at thermals and other wind considerations.

Don’t Get The Wind? Hunt High.

The first thing you need to know is that once you get down into tricky topography like valleys, saddles, draws, etc, the wind is going to begin doing funky things. I once heard wind described as water flowing in a creek. When the water runs over pebbles or hits a large boulder, it forms rapids, goes around it, swirls or eddies. Wind works the same way with hills, valleys and bends in a ridge. When wind comes across these topographic features it swirls, switches directions or does a number of other unpredictable things. This being said, you’ll find that treestands in locations such as valleys or on hillsides will often result in variable wind directions, which often can lead to blown chances at deer. Given this conundrum, until you fully understand how wind flows in these situations, it is most often a better idea to hunt higher up, in flat areas. There are plenty of great strategic locations that you can set up on that are on higher ground, resulting in more consistent wind.

Understanding Thermals

If you are going to venture into the world of hunting hillsides or valleys, it will be incredibly important for you to understand thermals. I’ll be honest with you, up until last year I had no idea what thermals had to do with hunting. But given some new education, I know they will change the way I hunt in many situations. So first off what are thermals?

Thermals are the result of air warming, or cooling, and then accordingly moving air up or down, sometimes along a hillside or ridge. On calm mornings, when the valley floor begins to warm, that heat will begin to rise and will result in an updraft of air moving up the hill. On evenings when the temperature begins to drop, that cold air sinks to the bottom of the valley again, bringing with it that draft of air down the hillside. Understanding this simple fact of nature can make a huge difference in how you play the wind when hunting. Very often these thermals can be stronger and more consistent than a “prevailing” wind, so if you are in a thermal situation, play the wind that results from them.

One interesting theory I heard about, from the “Hunting Hill Country Bucks” DVD, is that this thermal effect can cause a sort of “thermal tunnel”, where the thermals and the prevailing winds hit eachother. This supposedly occurs about 1/4 of the way down a hill or ridge. Very often deer will travel this “tunnel” along the length of a hill. Whatever side of a hill has the convergence of thermals and prevailing winds, should also have the most movement. I can’t say I have any personal experience to back this up, but it’s an interesting idea to consider.

Make sure that when hunting a ridge or hillside that you keep these thermals in mind. If it’s a morning hunt and thermals will be bringing warm air up the hill, hunt above a trail you expect deer to come across. If it’s an evening and you expect thermals to be pulling air down into the valley, make sure you are below the trail or destination you want deer to come through.

For a more visual explanation of how thermals work, check out this video from Melissa Bachman of North American Hunter.

How Deer Use Thermals When Bedding

One of the most interesting pieces of information I learned while diving into thermals was how deer use them when bedding in hilly areas. Consider this scenario, we have a hill with east and west facing slopes. When a prevailing wind is coming from the west and a thermal is pulling up the east hillside in the morning, these two drafts of air will meet on the east hillside. This is exactly where big, mature bucks will bed. It makes sense when you think about it. A deer’s #1 defense mechanism is it’s nose, so in this situation a buck can scent check it’s blind spot, behind it, while also smelling and surveying the land in front of it and down the hill. If the prevailing wind was from the East, you could expect this buck to be bedded on the west. Keep this factor in mind next time you’re trying to determine where those old bucks could be bedding.

Always Monitor and Learn From The Wind

No matter how much you understand about wind behavior in these unique terrains, wind can always surprise you. So make sure you actually check the wind when you’re in the tree, see how it plays out and learn from it. But don’t just check how the wind is blowing in your tree, check how the wind is moving down on the ground. One tip for this is to use milkweed to release into the wind and then watch as the wind carries it away. This will give you a good idea of how wind is actually moving through the area and how it is effected by trees, terrain features, etc.

What Else Would You Add?

Now all this being said, I know there is plenty more to be considered when it comes to wind, thermals and especially wind considerations in hilly terrain. It’s certainly a subject that takes a lot of first hand experience to fully understand and apply, and I am excited to dive even deeper into this come hunting season 2011. In the mean time, I would love to hear any further observations or advice that you might have on the topic of wind and thermals! Please share in the comments!

In addition to my own experiences, much of what I learned on this topic came from “Mapping Trophy Bucks” by Brad Herndon and the “Hunting Hill Country Bucks” DVD from Blood Brothers Outdoors. Click the linked titles to learn more about these great resources or to pick up a copy for yourself!

Check out our other posts in this series…

Understanding Terrain for Deer Hunting Success: How I Got My First Buck