Big white-tailed deer stir all kinds of emotions in me, but this one—a hulking Minnesota 10-pointer—had forced me into a time warp. My body was certainly living in the moment, my knees trembling as I watched the buck emerge from a rain-soaked sumac thicket and shake himself like an oversized Great Dane. But my psyche was transported back to my boyhood—specifically, to a memorable story I'd read about Daniel Boone killing a grand buck over a mineral lick.
Some 20 yards from my treestand was a pawed-out depression in the dirt. It was created by hundreds of whitetail visits to a highly specific area in the soil. I'd found the spot while scouting the previous spring. I didn't know whether I'd found a natural mineral lick or simply a spot where a previous hunter had dumped pounds of salt or mineral. All I knew was the place screamed for a treestand, so I hung one and waited for fall. I encountered the huge buck on my first visit to the spot.
My shaking continued for several long minutes after the buck had air-dried himself. As he approached the "lick," I struggled to come to full draw when something—a slight noise or, perhaps, deep instinct—made the buck pause to re-check his surroundings. Panicking, I jerked my sight-pin toward his shoulder and released in one motion. The arrow slipped harmlessly under the buck. He whirled and evaporated into the sumacs like fog.
That hunt occurred more than 15 years ago, long before the popularity of improving whitetail nutrition and hunting opportunities by establishing food plots and providing mineral supplements. I still don't know whether that depression in the dirt was natural or man-made, but I've certainly pondered it recently as I've done research for this article. With hunter interest in food plots at an all-time high, it was only natural North American Hunter would examine the topic of minerals and mineral supplements. With that in mind, here's a look at an aspect of whitetail management that goes hand-in-hand with food plots and other land-management tactics hunters can employ.
A Natural Relationship
The hunters of Daniel Boone's era knew all too well that deer and other game animals were attracted to certain mineral-rich sites. Licks, springs and even bogs that were rich in minerals like sodium, calcium, phosphorous and magnesium attracted deer, elk, moose, caribou, bison and even sheep and goats. Needless to say, hunters—from Native Americans to early white settlers—were drawn to the same sites. Later, the appeal of mineral licks was observed by such naturalists as George Shiras and Theodore Roosevelt.
What pulls white-tailed deer to such mineral licks? John Ozoga, a respected wildlife researcher from Michigan, explained the attraction as largely seasonal. "The majority of licks are composed mostly of sodium, or salt," he said. "And deer are very attracted to salt, particularly during the spring and early summer months. During this period, most of the forage available to whitetails is high in potassium and water, yet low in sodium. This apparently creates a sodium deficiency that deer attempt to fix by visiting natural mineral licks."
Ozoga says sodium is essential to healthy whitetail physiology, helping deer regulate "fluid volume and blood pressure, maintain osmotic balances and buffer systems." If salt is lacking in their diet, Ozoga says whitetails will retain it in their systems by simply passing less of it in their urine. But if a deer becomes severely salt-deficient over a long period, it could suffer impaired food digestion, decreased appetite and growth.
Salt, however, isn't the only mineral that's of importance to whitetails. Biologist and whitetail expert Dr. Grant Woods says calcium and phosphorous are also essential building blocks for whitetails. "They're both required as a doe produces milk for her fawns, or a buck grows antlers for the year," he said. "Each process is a very difficult one for deer."
Ozoga and Woods agree whitetails will—and do—"rob" their skeletal systems by drawing the necessary calcium and phosphorous from it if they're unable to obtain those minerals from outside sources. And they also concur deer will replace these vital minerals in their skeletons after fawns are weaned or antlers harden. That wild, free-ranging deer have accomplished this for centuries is testimony to their amazing resilience and adaptability. "All I know is, deer are amazing in their ability to find the forage their bodies need to not only survive, but flourish," Woods said.
The Million Dollar Question
Naturally, modern deer hunters—now learning the fundamentals and fine points of herd management—are wondering whether supplementing minerals will help whitetails during these peak times of high mineral requirement. Ozoga remains skeptical. "Recognizing the attraction deer have for natural mineral licks, I could be swayed to believe in supplemental minerals very easily," he said. "But to date, I haven't seen any scientific evidence to convince me."
Woods takes less of a hard-line stance. "Any research linking the benefits of mineral supplements for wild, free-ranging deer is inconclusive," he admitted. "So, ‘proving' that providing minerals will help bucks grow antlers or does nurse fawns is difficult. That said, I'm a big believer in minerals for the same reasons I take a multivitamin every day. Sure, I might not need everything that's in the vitamin, but I take one to cover my bases. The same goes for deer. If minerals help deer get something they're lacking, you're helping them achieve their potential. If you've got a bucket with a hole in it, you can pour all the water you want into that bucket, and the water will only rise to the level of the hole."
Matt Harper, a biologist for the Whitetail Institute of North America, is another believer in mineral supplements. Harper, who grew up raising cattle and has a degree in animal science from Iowa State University, said, "The benefits to other ruminants such as cattle has been shown conclusively for years. So I take more of a common-sense, logical approach. By providing deer with minerals they might need, you're ensuring they'll face no deficiency during a critical time of the year."
Harper also points to other evidence: "Since we (the Whitetail Institute) introduced mineral products, we've received thousands of testimonials from customers who've fed minerals religiously and experienced positive results. They're observing greater antler mass, fewer broken tines and improved antler scores among bucks of similar age class. Informal field observations like that will raise the hackles of any bonafide scientists, but we've just heard too much of it to ignore. I believe minerals do result in healthier whitetails."
Despite scientific backup, there's little doubt hunters—especially those hoping to maximize whitetail potential on their property—will continue to provide minerals for deer. For these users the question then becomes: How do you go about selecting and administering minerals to achieve the most bang for your buck?
Buying a high-quality product seems the most logical starting point. Most established companies have invested countless hours and dollars in research to discover not only what minerals are essential to whitetails, but when deer need them most and how best to deliver the goods. "We like to say the trick with whitetails is first figuring out what they need, then figuring out how to get them to eat it," Harper said. "Some minerals, such as calcium and phosphorous, are downright bitter to deer."
Salt, as we've discussed, is highly desired by whitetails and is a common—if not dominant—ingredient in many mineral blocks and mixes. In fact, some less-than-reputable manufacturers will rely almost exclusively on salt, which deer consume voraciously for a time, especially during early spring and summer. "But a whitetail's need for salt declines quickly," Woods said. "You can continue to use it to attract deer, but the ratio of salt should be altered so you can deliver other minerals to them."
Consequently, manufacturers like BioLogic (for whom Woods consults) and Whitetail Institute rely on a three-part system for delivering proper minerals. Simply put, the ratio of salt and other minerals is altered in each of three applications. "Basically, we believe administering minerals should go in stages that reflect the whitetail's need at a specific time of year," Woods said. Harper likens Whitetail Institute's three-part delivery system to "the feeding program a dairy farmer has for his cows. The feed/minerals they receive is altered according to their physiology—whether they're lactating or dry—at the time," he said. "It's the same principle."
While we don't have room to cover the specifics of any manufacturer's recipe—or how whitetails might benefit from each element—Woods and Harper concur on the primary ingredients. "You can break minerals down into two categories," Harper said. "Macro minerals are the most important building blocks and include salt, calcium and phosphorous. Trace minerals are needed in much smaller quantities, but can be important to deer in some specific areas. These include magnesium, copper, selenium, iron, cobalt and zinc."
Hunters should expect to see whitetails consume minerals heavily during spring and summer months, then drop sharply as autumn arrives. "Usually, by the time plants are hardening in the woods, deer have less use for mineral licks," Woods said. "In most places, by the time hunting seasons open, a whitetail's use of licks will have diminished or dropped off altogether." Nevertheless, hunters should be aware of state regulations regarding hunting near salt blocks or other mineral licks.
Also, whitetails in some areas might be more attracted to mineral licks than deer in other habitats. "In regions with heavy lime deposits, such as those along major rivers like the Mississippi, whitetails might not need or seek out minerals as actively," Harper said. "But areas with acidic soils will typically be minerally deficient and deer might use them heavily. Still, I've known very few areas where deer wouldn't benefit from mineral supplementation. I live in Iowa, a place where whitetails seemingly have no problem getting high-quality nutrition. Yet I've been using minerals for many years on my land and have noticed significant gains—both in body size and antler quality—in the bucks living there."