Buckmasters Magazine

The Language of Smells

The Language of Smells

By Bob Humphrey

Whitetails communicate as much with smell as they do with vocalizations.

It was the fourth day of my Kansas bowhunt, and things hadn’t gone particularly well. A clean miss the first morning and unseasonably warm temperatures had haunted me for three days. Somehow I had to make amends, but with rain and more high temperatures in the forecast, things weren’t looking good.

As my guide dropped me off, he handed me a small brown bottle of Tink’s #69 and advised me to use it all. “Pour it all around your stand,” he advised. I did him one better. First, I pulled out my drag and soaked it with lure. Then, I walked out about 100 yards from my stand and dragged the wick back. I repeated the procedure, dragging from four other directions, and then settled in.

It turned out to be quite an eventful morning. Three bucks sauntered by, all well out of bow range. However, when each hit my drag trail, they turned and walked directly to me. The third one paused in my shooting lane just long enough to accept an arrow to the boiler room.

Learning a Foreign Language

Anyone who’s ever tried knows how difficult learning a foreign language can be. Comedian Steve Martin used to joke about going to France, “It’s like they have a different word for everything.” Trying to understand and speak whitetail is even more difficult, partly because we make it so.

Since our primary means of communication is language-based, we try to communicate with whitetails similarly. Grunts, bleats and blats work, but vocalization is really a minor component of whitetail communication, perhaps like hand gestures are to humans. Many hunters fail to realize that scent is a far more important means of communication for the whitetail. We could do a much better job of communicating with them if we spoke the language of scents.

Consider the Source

Before we can begin to understand the “vocabulary,” we first need to understand how the “words” are made. White-tailed deer have five sets of external glands that secrete scented compounds.

Three — the tarsal, metatarsal and interdigital glands — are located on the extremities. The preorbital and forehead glands are on the head.

These five glands secrete several different compounds. One is called a pheremone — a chemical “messenger” that conveys information often designed to elicit a specific response. Many animals, from insects right up to humans, secrete pheremones to attract a mate.

Glands also secrete volatile fatty acids: compounds that transform from a liquid into a gas (evaporate) at normal temperatures. Each gland secretes a slightly different compound, or mix of compounds, for different purposes.

Tarsals

Most hunters are familiar with tarsal glands, which are just under the large tuft of hair on the inner surface of the hind legs (hocks). At least one study concluded that tarsal scent is used for individual recognition. It is also used to signal dominance and readiness to breed. All deer, particularly bucks, rub-urinate (rubbing their tarsal glands together, at the same time urinating on them). In the case of a rutting buck, this is often done while standing over a scrape.

In addition to scent, the tarsal glands secrete lipids (fat). The combination of fat, urine and glandular scent stains the hocks dark, giving the hair a stiff, waxy texture and a strong, musky odor. You can often see dark-stained tarsals from a distance, a good indication that a buck is in rut.

Metatarsal

The metatarsal gland is little more than a large, dark pore on the outer surface of the rear leg. Research on mule deer and blacktail deer, which have much larger metatarsal glands, has shown this gland is the source of an alarm pheremone that can alert other deer to the presence of danger. This gland is much smaller in whitetails, and scientists aren’t certain if it serves the same function or is merely a vestige of an earlier evolutionary version of the whitetail. Or it could be performing a function often mistakenly attributed to the interdigital glands.

Interdigital

We can’t see them because they’re hidden between the hooves, but interdigital glands perform a very important function. They release pheremones that leave scent trails wherever a deer walks. This probably makes it easier for them to find one another in dense foliage, or if they become separated.

This is particularly important for younger deer that might have been separated from their mother. Incidentally, fawns do not produce interdigital gland odor for the first few weeks of their life, making it more difficult for predators to find them. It has been suggested that deer stomp their feet to release interdigital scent, signaling alarm.

Studies from the University of Georgia show that the molecules in interdigital scent have different volatilities, which means they evaporate at different rates. This causes the odor of the track to change over time, which is how a deer (or a predator) can tell how old the track is and which way its maker was traveling. It’s the same principle that allows hunting dogs to know which way to follow a track.

Pre-Orbital

While we don’t know a lot about the pre-orbital gland, either — located in the front corner of the eyes — it seems to be pretty important. Deer rub trees and bushes with their pre-orbital glands. This occurs far more often around scrapes, particularly on the overhanging licking branch. Deer scent-check the licking branch to see who’s been by lately.

They will sometimes take it into their mouth, bringing it closer to a scent-detecting device on the roof of the mouth called the vomeronasal organ. (Bucks sometimes open their mouths, flare their nostrils and suck in air across this organ, a behavior referred to as flehmen.) They may even moisten the licking branch with saliva to make scent detection easier, which is probably where the licking branch got its name.

Forehead

The forehead gland lies beneath the skin between the antlers and the eyes. Like the tarsal gland, it secretes both scents and lipids, which is why a buck’s coarse forehead hair often becomes darker and more malodorous during the rut. Deer use it in much the same way as the pre-orbital gland, delicately working it against twigs and limbs to transfer scent. They also aggressively rub tree trunks.

Rubs have long been one of the most misunderstood aspects of whitetail behavior. It was once believed that deer rubbed trees solely to rid their antlers of velvet. We now know that velvet will shed whether they rub or not, and that rubbing is more a result of testosterone-induced aggression as deer unwittingly build their neck muscles for the impending rut. It’s also a means of communication.

If you’ve ever watched a buck make a rub, you’ve noticed he uses not only his antlers, but the base of his antlers and forehead to rub the tree (I’ve even observed does rubbing). While a fresh rub provides a visual cue, the most important utility of a rub might be as a scent post for territorial and dominance communication.

As a buck rubs a tree (or a licking branch), he deposits pheremones from his forehead gland. This gland becomes more active during the rut, particularly in dominant, mature bucks. And if you’ve ever noticed, a rubbing buck will often pause and sniff or lick the rub as he makes it. Maybe he’s checking to see if he’s overpowered another buck’s scent?

The Language of SmellsUrine

Deer also use urine as a means of scent communication, alone or in conjunction with glands. At certain times of the year, particularly the rut, levels of hormones like estrogen and testosterone change. These hormones alter the odor of urine, and with their keen sense of smell, deer can detect these subtle changes. Some studies have suggested that deer can detect dietary changes through urine odor as well, and may follow the scent trail of a well-fed deer to the food source.

Application

We’re only just beginning to understand whitetail scent communication. Without seeing or hearing it, a deer can tell when some other animal, be it human or deer, is nearby, or has been by recently. From another deer’s scent, which might be hours or even days old, they can distinguish sex, social status and breeding condition.

So how do we use all this information to speak to deer, in many cases trying to fool them?

For starters, we need to decide what we’re trying to say. Are you trying to convey that all is well, or are you speaking the language of love?

Urine-Based Scents

Let’s start with urine-based scents, as they’re the most popular. Passive scents like non-estrous doe urine and non-rut buck urine are designed to put deer at ease and can be used throughout the season. They can be applied with drags, on wicks or directly to vegetation. By using them, you’re conveying that other deer are or were around, and all is well.

Sexual attractants like doe-in-heat and buck-in-rut urine, on the other hand, are designed for, and best used during, the rut. Using them too far outside this window can alarm deer. Both say, “I’m looking for love” at a time when deer are not supposed to be amorous.

One popular application is a scent trail, made by dragging a urine-soaked rag or felt strip along a trail to your stand. Some hunters will even lay down several such trails around their stands — like spokes in a wheel, with their stand being the hub. When doing so, however, it’s important to remember that deer can age the scent. Always drag toward your stand.

Another effective technique for rut scents is creating a mock scrape. Estrous-doe scent tells a buck there’s a receptive doe in the area, and the musky odor of a rutting buck represents a challenge to the local dominant buck. Either could draw a mature buck out during daylight.

Glands

Though used less often, you can say a lot more with glandular scents. One of my favorites is interdigital scent. It merely says “a deer walked by here recently.” But that can be a very strong message. Deer are curious, and even outside the rut will follow the trail of another deer.

Furthermore, it puts them at ease by saying one of their kind has been by recently. Think about how many times you’ve observed that when one deer passes by your stand on a particular trail; subsequent deer almost invariably follow that same trail.

Also, you can use interdigital scent from early bow season in September, right through to late winter seasons. It is a non-threatening scent, so it won’t alarm younger or subordinate deer, and it works equally well on bucks and does. It is best used on drags or scent pads but can be applied directly to low-lying vegetation or the ground.

Scent from the tarsal glands is popular, too. When I began deer hunting, there was a widespread misconception that if you killed a deer, you had to remove the tarsal glands to avoid tainting the meat. Being both frugal and insightful, I used to collect those tarsals and tie them onto my fanny pack (I still do) as a cover scent and attractant.

I sometimes tie them on my boots to create a drag trail or hang them on trees near my stand. Passing deer can’t resist them, and when they stop to sniff, they become vulnerable to a shot.

I have less experience with scents from the forehead and pre-orbital glands, mostly because they’re hard to come by. If you can find them, the best application is on rubs or licking branches. However, you can do the same thing with tarsal and urine scents. Here, gel or paste form is better, as it will adhere to vegetation and last longer.

The Best of Both Worlds

Several companies now produce blends, containing both urine and glandular scents. In terms of scent-speak, they’re saying several things at the same time. For example, a mock-scrape blend might contain both rutting buck and estrous doe urine, and perhaps even some glandular scents. Such combinations tell other deer that the rut is on and they’d better get in on the action. Another blend might contain both urine and tarsal scent from a rutting buck, a flagrant challenge to the local alpha buck.

Conclusion

The potential seems almost limitless. The more we learn and understand about how deer communicate using scent, the more we’ll be able to take advantage of that aspect of deer behavior. In the meantime, it’s important to use the scent knowledge we currently have when we go to the woods. In other words, know at least the basics of what you want to say to deer and how to say it. It’s kind of like going to a foreign country. As long as you can ask for a beer and directions to the rest room, you can get by.

This article was published in the November 2007 edition of Buckmasters Whitetail Magazine. Join today to have Buckmasters delivered to your home.

Copyright 2017 by Buckmasters, Ltd.

Copyright 2017 by Buckmasters, Ltd