Buckmasters Magazine

Ask the Biologist

Ask the Biologist

By Bob Humphrey

Deer hunters have an insatiable curiosity about the fascinating creatures they pursue.

From the time we first walked upright on this continent, man has been inexorably tied to the white-tailed deer. For millennia, we depended on them for our very survival. Today, they remain the most popular big game animal in the world and account for more hunting effort than all other species combined. Even though our survival no longer depends on deer, hunters have an insatiable hunger for knowledge about these remarkable creatures.

As Buckmasters’ go-to biologist, I’ve had a great time answering your questions on the “Ask the Biologist” section of Buckmasters.com. While the questions are numerous and varied, there are some that pop up on a regular basis. If there are enough folks motivated to ask, there are probably many more who are just as curious but aren’t the type to raise their hands in class.

Here are some of the more common questions and answers.

RUT DATES

We’ve had questions from hunters all over the whitetail’s range asking when peak rut occurs in the area they hunt. In fact, we received so many it prompted a full feature article in Buckmasters magazine called “The Rut Calendar,” which we update periodically.

First, it’s important to understand the distinction between peak rut and peak breeding dates. The rut involves all activity related to seeking, chasing and ultimately breeding a receptive doe.

To a biologist, peak rut is peak breeding, when the majority of bucks and receptive does pair up and melt off into some secluded area, where they’ll remain sequestered until fulfilling their biological purpose in life. To a hunter, peak rut is that period when bucks are most active during daylight hours, which typically precedes peak breeding by a week or two.

To create our rut calendar, we contacted biologists from every state and several provinces where whitetails live and asked when their peak rut occurs. Peak dates varied from state to state, and sometimes within different regions of the same state. However, every biologist reported that, with very little exception, peak rut dates for any particular area do not vary from year to year. Once you learn it, whether from our calendar, your local biologist or your own observations, you can count on it being the same, year after year.

Keep in mind that doesn’t necessarily mean you’re going to see mature bucks wandering around willy-nilly on those specific dates. While the dates don’t change, numerous factors can influence the degree and type of daytime activity that occurs. If it’s warm, stormy or there’s a lot of hunting pressure, more rut activity will occur at night. Sex and age ratios and population density also play a role in how much activity you see in a given year.

MALADIES

As enthralled as we are with the ordinary, our curiosity and fascination with whitetails goes to a whole new level when it comes to the extraordinary. Another regular source for questions, understandably so, are the various maladies that affect deer.

Among the most common are dark skin lesions called cutaneous fibromas. They are essentially a benign tumor or wart believed to be caused by a papillomavirus, which is possibly transmitted by blood-feeding insects.

Fibromas are typically dark gray or black, although occasionally they can be un-pigmented, tan or white. They may show more red, particularly if they are scratched and bleeding, and abrasion can sometimes result in secondary infection.

Fibromas are more common in younger deer and, in general, pose no harm to the animal and no health risk to a hunter. The initial infection stimulates an immune response in the host deer, and eventually the fibromas may stop growing, then dry up and go away. However, fibromas can affect deer health if the growths are large enough to interfere with sight, breathing, eating or escaping danger.

Another common malady is a skull abscess. This type of injury is fairly common, particularly in bucks, and especially during the rut. One study suggested it accounts for slightly less than 10 percent of the natural mortality for yearling and adult male white-tailed deer in the Southeast.

It is caused by bacteria that naturally inhabit the skin of a deer but enters the brain through lesions, skin abrasions or other injuries. Among the most common type of injury is damage to the antler pedicel (where the antler attaches to the skull) or the sutures (ragged lines where the different bones of the skull are fused together).

The greatest mortality occurs in fall and winter. A buck thus injured rarely recovers. More often they succumb to their injuries and die an ugly death.

ODDITIES

We also get a lot of questions about different deer pelage (fur color). A whitetail’s pelage varies seasonally, from red in the summer to brownish gray in the fall. Fall colors can also vary among individuals as different shades of brown and gray. Occasionally, fawns will retain their spots into adulthood.

Then there are genetic mutations. Piebald and albino deer result from a recessive genetic trait that causes a lack or absence of pigment. Albinos totally lack body pigment. Their fur is white, and their eyes, nose and other soft parts are pink. Piebalds do not completely lack dark pigment but have varying amounts of brown fur. Their hooves, eyes and nose are dark.

Both are exceedingly rare – estimated at less than 1% – under natural conditions. Because the conditions are genetically based, the phenomenon is often localized where it occurs.

In the wild, such fur abnormalities place animals at an immediate and selective disadvantage.

Lacking typical protective coloration, white deer are more visible, making them easier for predators and hunters to locate. The genes that control fur color are pleitropic, meaning they control multiple traits. White deer sometimes have other recessive traits such as poor eyesight, bowing of the nose (Roman nose), short legs, arching spine (scoliosis), and short lower jaws and smaller antlers.

White deer aren’t the only odd color phase we get questions about. We occasionally hear about much rarer black or melanistic deer, which have greater than normal amounts of pigment.

The most unusual coloration we’ve ever seen was a photo of a deer with silver hair and lemon yellow eyes. It was so odd I consulted several whitetail experts.

Dr. Karl Miller, professor of wildlife ecology and management at the University of Georgia’s Warnell School of Forestry and Natural Resources, described it as “occasionally reported but extremely rare.” He added that they had a similar one in their deer pens several years ago, although she was more blonde than silver, and reverted to normal color in subsequent years, leaving little clue as to what caused her condition.

Miller also added this phenomenon is so rare there’s no name for it; so I made one up: “Silver Deer.”

SENSES

Of all the senses deer use to avoid predators, hunters seem to be the most curious about vision, perhaps because that’s where some of the most interesting research has been done.

Much of what we know about deer vision is the result of Dr. Miller and his associates at the university. They’ve examined deer physiology and actually implanted sensors in captive deer so they could record which wavelengths of light stimulate brain activity and which parts of the brain they stimulate.

They learned that deer have only two classes of color-recepting cones (humans have three). Furthermore, they determined that unlike the trichromatic (three-color) vision of humans, deer vision is most sensitive to short wavelength (blue-violet) and middle-wavelength (green-yellow) light.

Also, their lenses lack the yellow pigment of the human eye, which filters out ultraviolet light almost completely. As a result, their sensitivity to blue and violet is much greater than ours.

Their sensitivity is lowest in the middle to long wavelength region of the color spectrum (yellow-green, green, yellow, orange and red). To them, orange and red appear only as different shades of gray, which is why they aren’t particularly alarmed by blaze orange. More often it’s the solid human form or movement that catches their eye.

ANTLERS

We get so many different questions about antlers that it’s hard to generalize.

One common theme is non-typical or irregular antlers, for which there are several possible causes.

The first is genetics. Some deer are genetically predisposed to grow non-typical racks. Another is age. As deer grow older they tend to grow more abnormal points. A third cause is injury.

While growing, antlers are soft and pliable. Injury can result in a range of malformations like bent or twisted beams or tines, acorn points or holes.

A somewhat common phenomenon is bucks with a spike on one side. One study found the probable cause in 34 of 44 cases was pedicel or skull trauma, likely due to fighting. I can only guess these deer were fortunate not to suffer abscesses. The other cases might have been the result of old gunshot wounds, healed leg fractures or other skeletal injuries.

The latter two represent one of the more interesting phenomena of antler growth. If a buck suffers injury to a rear leg, the antler on the opposite side of the body often shows abnormal growth. If the front leg is injured, abnormal growth more often occurs on the same side. We don’t know why this happens.

FOOD PLOTS

We get a ton of questions about food plots. Unfortunately, the variety is so great it would be impossible to generalize for the purposes of this article.

The best advice I can offer is to check our “Ask the Biologist” section of Buckmasters.com on a regular basis and watch for feature articles in Buckmasters.

DISAPPEARING DEER

We get all sorts of questions about deer behavior, but the most common by far is the case of disappearing deer.

“We see them all summer,” folks write, “and even get nighttime pictures on our trail cameras. But once hunting season begins, the big bucks seem to disappear. Where did they go?”

For better or worse, the answer is fairly simple. Deer shift habits within their home ranges according to availability and abundance of preferred food sources. However, several studies that looked at how hunters influence deer movement found that, in general, deer do not leave for good.

Instead, as hunting pressure increases whitetails move less during daylight and spend more time in thicker cover.

FINALLY

At some point in your education, someone probably told you, “The only stupid question is the one you don’t ask.” The same applies to deer hunting. If you want to be more successful, you need to learn as much as you can about the game you pursue. (Here comes the shameless plug.) Keep sending your questions for the “Ask the Biologist” web feature, and check in often to see what other hunters are asking.

If enough of the same questions keep coming in, the answers might appear as a feature in this magazine.

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This article was published in the Winter 2015 edition of Buckmasters Whitetail Magazine. Subscribe today to have Buckmasters delivered to your home.

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Copyright 2020 by Buckmasters, Ltd