Mineral block bucks from yearling to 5-1/2 year-old from a calcium poor area in Northern Minnesota.

Back in 1970 I often wondered if a lack of adequate calcium and phosphorus might be the reason so many yearling bucks in my original Minnesota whitetail study area were spike bucks, about two for every forkie. To find out, I placed four cattle-type mineral blocks in the western half about the first of May that year, the beginning of the antler growing season, That fall the numbers were reversed, two out of three yearling bucks were forkies or better (one even an eight-pointer with a nine inch spread). Then wondering if mineral blocks could increase the size if antlers grown by older bucks in my low-calcium study area, I continued setting out blocks every spring for 19 years and compared masses of antlers of bucks of same ages taken in the treated half with antlers of bucks taken in the untreated half every year. I did this by filling a large pot to the brim with water placed in a larger pan, submerging the antlers in the water and then measured the amount of water that overflowed into the pan. Antlers from the treated half averaged about 10–20% greater in mass than antlers from the untreated half. Moreover, numbers of surviving fawns (in wolf country) in early November throughout the following 18 years were always about 10– 20% greater in the treated half. Convinced of the benefits of mineral blocks, capable of enabling some bucks with 150–inch antlers (Boone and Crockett measuring system) to grow 170 or 180–inch antlers, my sons and I have been placing mineral blocks throughout my second primary study area every spring since 1990. Though we have not continued comparing antler sizes since then, the number of bucks worthy of being mounted taken by my sons, daughters, grandsons and I since 1990 is eight times greater taken than the number taken by an equal number of my family, including uncles and cousins, between 1945 and 1989.

In recent years sporting goods stores have become filled with a great number of products claimed to enable bucks to grow larger antlers, some in liquid form and powder form and some even being seeds. Last spring my son John and I decided to try a different, less expensive brand of mineral blocks claimed to grow larger antlers. When we checked them while scouting last October, they were gone, and judging by the lack of hoof prints and wear around the sites where they were placed, they were gone well before the antler growing season ended (growth ends about the first of September). This was strange because the more expensive blocks we had traditionally used always lasted 2–3 years. From now on, we decided, we’ll stick to using what we know works: our usual $12.95 much-more-durable cattle type 40–50 pound mineral blocks with the top two listed ingredients being calcium and phosphorus (the primary ingredients of bones and antlers) followed by a trace of needed zinc, a trace of unneeded salt and vitamins.

We place our blocks on exposed roots of mature evergreen trees where well hidden by surrounding cover. A mature evergreen protects the blocks from rain, making them last longer. The surrounding cover keeps them from discovered by other hunters who might decide they’ve discovered a great stand site. Actually, mineral blocks are very poor stand sites. Neither bucks nor does are much interested in mineral blocks during hunting seasons because by then antlers of bucks are fully grown and fawns of does are fully weaned. Wherever mineral blocks are placed, 4-6 deer of the near vicinity will quickly find them and create beaten paths leading to them from several directions.

To get the desired antler growth, the blocks should be placed within or near bedding areas of mature bucks. The reason is, while growing antlers, older bucks tend to be recluses, bedding, watering and feeding in or near their secluded, difficult-to-find hideaways only 1–2 acres in size. While scouting in search of them, look for plenty of fresh and old tracks 3-1/2 to 4 inches long, fresh and old droppings 5/8 to 1-1/4 inch long, beds in deep grass 45 to 56 inches long and clusters of six or more antler rubs on tree trunks 2–4 inches or more in diameter — characteristic signs of bedding areas of mature bucks. Where you find plenty of fresh mature buck sized tracks and droppings, you are probably close enough, especially if near water. We typically place 2–4 blocks in or near buck bedding areas per square-mile.

My sons tote mineral blocks with their hands. I prefer carrying one block in a large plastic bag in a packsack attached to a heavy-duty pack frame along with 2–3 bottles of water and much-needed insect and tick repellent or two blocks tied down on a plastic toboggan. It’s now mid-April, an ideal time to take care of this chore. Early May is okay.

By the end of a day of scouting and dropping off mineral blocks, my sons and I are usually weary and hungry but grinning, anxious to share our findings over a meal at a lakeside resort on the way home. Our grinning reveals we have each found some fresh tracks in the 4-inch range, fresh droppings 7/8-inch or more in length, antler rubs on tree trunks 4 inches or more in diameter (rubs made during the previous fall) and/or beds 50–56 inches in length — signs only made by trophy class bucks. Following this particular day in spring, fall can never come quickly enough.

An afterthought: since whitetails can’t be kept from congregating in wintering areas in winter, I have often wondered if a drug could be added to mineral blocks that can kill parasites such as brain worms in deer and moose, not fatal to whitetails but sometimes fatal to moose. After researching this, my son John recommends the tapeworm dewormer Praziquantel as an example. Similarly, I wonder if adding a proper drug could be a way to eliminate chronic wasting disease in whitetails.