The latest on how deer communicate with sight and sound.
Perception is defined as the organization, identification and interpretation of sensory information. Not only must an animal see, hear or smell something, but it must also decide what it means. Sense organs — ears, eyes and nose — are the information detectors, while the central nervous system (brain) does the interpreting. Systems differ considerably between species, which is why human perception of the environment is very different from that of a white-tailed deer. If you want to be a more successful hunter, it’s important to know more about a whitetail’s perception.
To date, there have been only two in-depth studies on deer vocalization. Dr. Karl V. Miller was a researcher and coauthor of a 1988 study at the University of Georgia’s D.B. Warnell School of Forest Resources. Miller is a now a professor of wildlife ecology and management at the University of Georgia, where he and his graduate students continue examining vocalizations.
Miller and his team have also conducted some groundbreaking work on deer vision, thanks in part to the tremendous resources at their captive deer research facility. It was at that facility where Miller’s group identified several distinct deer vocalizations.
Deer are social animals, and when a member of a social group finds itself out of sight of the others, it might utter a contact call or grunt.
“It’s a low, guttural call, difficult to identify the location of,” Miller said.
A hunter might use a contact grunt if there is a group of deer milling around in thick cover. A contact call might could coax at least one deer into coming your way.
A deer sound you don’t want to hear and certainly don’t want to imitate is the snort, or blow. Rather than a true vocalization, it is a loud expulsion of air, typically issued when a deer is startled.
A deer makes a quick snort and then bolts. Somewhat similarly, if a deer senses danger – maybe catches a whiff of human odor but isn’t sure of the source – it might issue a series of long, prolonged blows.
Don’t lose hope if a deer blows at you. According to Miller, that deer probably hasn’t gone far from where you heard it. If you’re on foot, you might be able to use the wind to your advantage and out-flank the deer. It’s a low-percentage move since all deer within hearing range will be on high alert, but you’ve little to lose since the blowing deer won’t come your way any time soon.
Another call with limited utility to hunters is the bawl. According to Miller, it is an expression of anguish, possibly due to an injury. You wouldn’t use it to attract deer, and you might want to investigate the source if you hear it. It could be a deer caught in a fence, being taken down by coyotes or one badly injured from a fight.
Miller’s group identified three aggressive calls hunters should know. The first is a low, aggressive grunt. Miller says it’s one deer’s way of telling another, “You’re doing something I don’t like,” such as a buck warning an interloper to back off a hot doe.
As the intensity of the interaction increases, the grunt might become a grunt-snort. If the interloper persists, his rival might issue a grunt-snort-wheeze.
“This is the most aggressive sound a buck makes,” Miller said. “It’s usually a mature buck, and when he utters it, the other buck will either back down or return the aggression.” If that happens, there’s going to be a battle.
Miller recommends using the snort-wheeze sparingly. It’s liable to scare off younger, subordinate deer because it represents a direct challenge to older, more dominant bucks. If you’re after only a really big buck, however, you might want to give it a try.
Another call hunters should know is the tending grunt, issued by a buck tending a doe he perceives to be in estrus. It’s higher pitched than the aggressive grunt and can vary from one or two short grunts to a longer repetition. I’ve witnessed randy bucks make tending grunts with almost every exhalation as they chased does.
According to Miller, don’t be too concerned about achieving the exact tone.
“Individual deer have variation in their voices, just like humans,” he said. Most hand-blown mouth calls provide a reasonable imitation.
Does and fawns interact vocally through several calls. One is a variation of the contact grunt. A doe uses this to tell her fawn, “It’s time for you to bed down while I go off to feed.” When she returns, the doe might not know exactly where her fawn is bedded and will issue another grunt that says, “I’m back. Come and find me.”
The nursing whine is just what the name implies: a fawn telling its mother, “I’m hungry.” The mew is a care-soliciting vocalization – something a fawn might utter if it becomes temporarily separated from its mother.
If the fawn becomes more anxious or is in danger, it might utter a bleat. This is a more significant sound, and a doe will often respond readily. Miller says a fawn bleat can be extremely effective if you’re trying to harvest does during early archery seasons.
Humans put a great deal of emphasis on vocalization because it’s our primary means of communication. Not so for deer. According to Miller, whitetails do far more non-vocal communication, and he emphasizes looking for subtleties.
“When they’re in a group, deer are constantly communicating with one another although they might never make a sound,” he said.
There are numerous postures deer use to communicate, many of which we’re still trying to understand. Some are obvious, like when a deer stops, throws its head up and stares, usually looking for potential danger. Another overt gesture hunters often see is the foot-stomp. It means, “Hey, pay attention!” The deer is communicating to the rest of the group that something is amiss.
Other postures are more subtle. One buck averting its eyes from another can be a gesture of submission. Miller offered the example of bachelor groups.
“Let’s say you see several bucks together and they’re all looking in different directions,” he said. “It’s not so they can watch for danger. It’s to avoid direct eye contact,” which is a gesture of aggression.
Miller also noted that after pre-rut sparring, particularly between bucks of unequal stature, the loser often grooms the forehead of winner.
“He gets a good taste of that buck. Later, if he smells it on rubs in the area, he knows he needs to be careful.”
Some gestures – like pinned back or dropped ears – are threat postures or signals of intent, according to Miller, and are generally accompanied by a guttural grunt.
This can be part of a head-high or head-low threat. The head-high posture is more common in does, or bucks outside of the rut, Miller observes. During the rut, bucks use the head-low posture to emphasize their antlers.
Other aggressive postures include turning sideways to show off body size, and piloerection, when a deer bristles to make its hair stand on end. It also darkens its body to make it look bigger.
You’ve probably seen a buck approaching a hot doe in a stiff-legged, crouched posture I call the setter walk. Miller says bucks do this to look smaller and less imposing, almost like a fawn approaching to nurse.
Another common gesture hunters see too often is flagging. White-tailed deer are gregarious animals that live primarily in dense vegetation where they use cryptic coloration to hide. A flash of white is not only a signal of danger, it tells other deer which way to run. Does flag more often because they’re often in a group, but bucks will also do it if they’re with other deer.
All this is useful to hunters. If you recognize subtle gestures and body language, you can try to interpret a deer’s mood and respond accordingly. A deer showing submissiveness might not be a good candidate for aggressive calling, but one showing dominant or aggressive body language could be.
Perhaps the biggest perceptive difference between deer and humans is in the way we see.
Our pupils – which dilate and constrict to regulate the amount of light that reaches the eye – are round, while a deer’s are oval and almost rectangular. This minimizes light energy from above and below while maximizing light from the horizon, where danger lies. Deer also have bigger pupils, which Miller says increases their light-gathering ability well beyond ours.
Additionally, human eyes have three types of photo pigments that peak at different parts of the visible spectrum: blue, green and red. Every other color is some combination of those three basic colors.
We don’t see in the blue part of the spectrum as well as deer because we have a yellow filter that blocks ultraviolet (blue) light. Most of our vision is in the red and green part of the spectrum.
Through research at the University of Georgia Deer Lab, we know deer have two photo pigments, one for blue and the other about halfway between our red and green.
“Light reflected in other parts of the spectrum, in the neutral zone, probably looks gray to them,” Miller said. “Anything that’s dark red looks black to a deer, and they don’t see blaze orange as well as we do.”
Dr. Brad Cohen, a member of Miller’s team, was able to determine that deer actually see into the blue part of the spectrum 20 times better than humans, largely because they lack the yellow filter.
With better visual acuity, our eyes are constantly moving because we’re looking at a point in space. Deer eyes don’t move because they’re seeing the “big picture.”
At twilight, when there is more ambient blue light compared to red and green, the ability to see blue is a powerful defense mechanism.
The University of Georgia team is also looking at the reflectance of various camouflage patterns in the blue part of the spectrum. Although the colors might all appear as greens and browns to us, different patterns reflect light in the blue part of the spectrum differently. The results, when available, could change the look of hunting camo.
Remember, getting information to the brain is only half the battle. Perception is both the detection and interpretation of sensory information. Like deer, hunters have the ability to detect sights and sounds in the woods. If you know a little more about whitetail senses and have a better understanding of how they view the world, you can use that information to be a more effective hunter.
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This article was published in the September 2015 edition of Buckmasters Whitetail Magazine. Subscribe today to have Buckmasters delivered to your home.