Four Years of Antler Restrictions in Michigan's DMU 118 - What Have We Learned?
By: Ed Spinazzola and Brian Murphy
Beginning in 1993 with the “Dooly County Experiment” in Georgia, several counties and deer management units (DMUs) across the U.S. have been placed under state-regulated antler restrictions. Today, numerous counties or DMUs in Georgia, Michigan, Louisiana, Texas, New Jersey, and other states are operating under some form of minimum antler restriction. These are in addition to statewide antler restrictions in Mississippi, Arkansas, and Pennsylvania. Collectively, these restrictions have resulted from the growing support among sportsmen for opportunities to manage and hunt whitetails under the Quality Deer Management (QDM) approach.
The notoriety of the Dooly County project spurred the interest of Michigan schoolteacher and avid whitetail hunter, Marc Yenkel of Claire, Michigan. In 1996, Marc petitioned the Executive Director of the Michigan Department of Natural Resources (MIDNR) for an antler restriction in his immediate hunting area of about three square miles. It was politely refused.
“We wanted a chance to harvest 2 1/2- or 3 1/2-year-old bucks,” said Marc. “People around here had bushel baskets of 4-point racks. We wanted the opportunity, the challenge of hunting an older deer. I have 160 acres and the guy next to me has 3,000 and it really snowballed from there.”
Despite the failed first effort, Marc gathered several local supporters and petitioned the Michigan Natural Resources Commission (MNRC) in 1997 for a larger area of about 20 square miles. This also was rejected on the basis that it would break-up an existing DMU. Marc then joined the Mid-Michigan Branch of the Quality Deer Management Association (QDMA) and together they drafted a proposal for all of DMU 118 (173,000 acres) with input from the MIDNR Wildlife Division.
Based on this request, the MIDNR adopted guidelines similar to those used in Georgia, which require, among other things, landowner and hunter surveys to be conducted in the affected area to gauge support.
A minimum of 66 percent support from both landowners and hunters is then required for the antler restriction to be implemented. Eventually, a survey was conducted, which revealed 68 percent support from landowners and 53 percent support from hunters for a mandatory 3-points-on-one-side minimum antler restriction in DMU 118. The MIDNR withdrew their support due to the hunter survey not meeting the 66 percent minimum support requirement. Still undeterred, Marc and his supporters petitioned the MINRC again in 1999 and were successful in obtaining the necessary 4-vote majority within the Commission to proceed with the regulation for a minimum of five years.
Unlike most other county-wide antler restrictions, DMU 118 provides a unique opportunity to objectively assess the potential of this approach because deer harvest data have been regularly collected for many years, both pre- and post-implementation of the restrictions. Now, four years into the 5-year program, the results have been very encouraging. The following results were prepared from data provided by the MIDNR.
As you can see from Figure 1, total deer harvest in DMU 118 peaked in 1999 (the year following implementation of the antler restriction) at 416 deer and appears to be stabilizing around 250 animals, or slightly above the 3-year base average of 235 before the initiative began.
Importantly, the sex ratio within the harvest has improved considerably. Prior to introduction of the antler restriction, an average of 1.9 bucks were harvested for every doe harvested. The 4-year average during this initiative was 1.3 bucks harvested per doe (range 1.1-1.7). Also, the total antlerless harvest exceeded the 3-year base average of 104 during each of the four years, including 2002 when 109 antlerless deer were harvested. The steady decline in antlerless harvest during the four years of this initiative is likely due to a reduction in total deer density as reported by many hunters in the area.
One of the most encouraging results was that, contrary to many predictions, total buck harvest did not decline under this restriction. In fact, in all four years, except 2001, total buck harvest exceeded the 3-year base average of 131 (range 117-203).
Another positive result was the decline in the percentage of button bucks in the antlerless harvest (Figure 2). The 3-year base average prior to the restriction was 19 percent, compared to the 4-year average during the project of 11.5 percent — a 39 percent reduction. It is likely that the increased survival of button bucks was a major reason why total buck harvest remained above the 3-year base average when the total herd was being reduced through increased antlerless harvest.
The impact of the restriction on the ages of bucks in the harvest also was encouraging (Figure 3). Following a slight increase in the number of yearling bucks harvested in 1999, this number has declined to around 60 — a 41 percent reduction from the 3-year base average of 102. This decrease occurred despite the fact that the 3-points-on-one-side restriction only protects around 50 percent of the yearling bucks in this area.
As expected, the protection of yearling bucks resulted in an increased harvest of older bucks. For example, the 3-year base averages for 2 1/2-, 3 1/2-, and 4 1/2+-year-old bucks were 21, seven, and one percent, respectively. In contrast, the 4-year averages for these age classes following the restriction were 49, 23, and four percent, respectively. This translates to increases of 133 percent, 229 percent, and 300 percent for 2 1/2, 3 1/2, and 4 1/2+ year olds, respectively.
While the data show a drastic improvement, the regulations were a hit with many hunters in the area.
“It only took about two years to see the results and it just keeps getting better,” Marc said. “This year I took a buck that grossed 107 inches and my son took a buck 97 inches, and they were heavy deer. The buck to doe ratio has improved drastically.”
The results from this study provide strong evidence that state-regulated antler restrictions can produce positive outcomes in whitetail herds, and in a relatively short period of time. At least in this example, it appears that the three primary objectives of this antler restriction — increased antlerless harvest, decreased button buck harvest, and increased harvest of older bucks — are being achieved. The increased antlerless harvest has apparently reduced deer density, which provides obvious benefits to landowners and agricultural producers.
The decreased button buck harvest demonstrates that hunter education and commitment to a QDM-type program are determining factors to hunter selectivity. The increased number of older bucks has resulted in a more balanced adult sex ratio and an increased number of older, larger-antlered bucks available for harvest. The increased presence of older bucks also increases the intensity of rutting activities and provides opportunities for hunters to incorporate rattling and calling techniques into their hunting strategies.
Despite the obvious success of this initiative, a recent survey by the MIDNR revealed that landowner and hunter support for continuation of the restriction is still below 66 percent. It remains unclear if the MIDNR will continue the restriction beyond the 2003 hunting season, the end of the initial 5-year period. Regardless, the results of this study reveal that the combination of proper doe harvest and protection of yearling bucks can produce positive outcomes for deer herds, deer habitats, and deer hunters.