Looking back over themes from 42 annual meetings of the Southeast Deer Study Group reveals the evolving concerns of professional whitetail researchers over the last four decades of North American deer hunting.
When the first meeting was held in 1977, goals still included restoring deer to a few last pockets of their former range. Quickly the question became, “Now that we have them, what do we do with all of them?” Talk in the 1980s turned to doe harvest as an answer to overpopulation problems. A new philosophy called Quality Deer Management began to dominate debates. As these revolutionary ideas settled into norms, new concerns arose: predators, declining hunter numbers, rising political interference in wildlife management. Then you arrive at the most recent meeting in February, hosted by the Kentucky Department of Fish & Wildlife Resources, where almost the entire first day of the two-day conference was dedicated to one subject.
You can probably guess it.
I look forward to the day when chronic wasting disease (CWD) is one of those concerns of the past.
Meanwhile, like past meetings, the rest of the 2019 conference covered useful and interesting new studies of deer behavior, biology, habitat and hunting. Below is a sampling of statistics I gathered, and QDMA members are reading about other new research in more detail in issues of Quality Whitetails.
0.5 to 0.8
Extra inches of antler carried by the average 5½-year-old South Texas buck for every inch of rain that fell in its first year of life. Masa Ohnishi of the Caesar Kleberg Wildlife Research Institute at Texas A&M-Kingsville examined age, antler scores and environmental effects for 2,937 individual bucks as part of a broader study of culling on the Comanche Ranch (see the December 2018/January 2019 issue of Quality Whitetails for more on his culling results). In arid South Texas, where variable rainfall also drives up-and-down cycles in native forage quality, annual rainfall can affect antler growth in any year of a buck’s life, but conditions in their first year may have permanent effects on lifelong baseline antler potential.
Decrease in pregnancy and productivity rates among yearling does (1½ years old) for every month-long delay in the average birth date of fawns in areas of the South with late rut peaks. Mark Turner of Auburn University found the late births associated with late ruts led to lower productivity for young does that are trying to catch up from being born late. The good news: By age 2½ they have overcome the disadvantages and are conceiving normal numbers of fawns compared to populations with normal rut timing.
Points earned by Hardeman County, Tennessee, in a 2018 risk assessment for chronic wasting disease (CWD) based on numerous predictive hazards, such as proximity to borders with CWD-positive states, locations of captive deer facilities, disposal practices of taxidermists and processors who had received whole deer carcasses from other states in the past, and other factors. This was the highest risk score of any Tennessee county, and it turned out to be accurate – a CWD outbreak centering on Hardeman County was discovered only months after this assessment was completed. “We wish we’d started a risk assessment like this eight to 10 years ago,” said James Kelly of the Tennessee Wildlife Resources Agency, who explained that the map could have helped focus limited resources for testing and monitoring on higher-risk areas. “Non-CWD states that haven’t done this yet need to get started.”
“Every year that goes by without cases in humans in those CWD endemic zones gives me more comfort, but I can’t say how long we need to wait.”
Increase in risky business (exposing themselves to hunters) during the peak rut by bucks classified as “movers” compared to those with more of a “sedentary” personality. Ashley Jones of Mississippi State University tracked 18 movers and 25 sedentary adult bucks on private hunting land. She also found 2½ and 3½-year-olds took significantly more risk during the peak rut than bucks 4½ and older, though in the post-rut it was mature bucks (5½-plus) that were taking more risks. Ashley had comforting words for heartbroken hunters who aren’t seeing a buck they really want to meet: “It’s not you, it’s him.”
$178 vs. $43
Cost per acre of planting native grasses and forbs after eradicating non-native tall fescue ($178) compared to the cost of simply eradicating tall fescue and allowing the native seedbank to respond ($43). Interestingly, Wade GeFellers of the University of Tennessee found that nutritional benefits for deer were essentially the same with both approaches, and in fact more than 95 percent of the selected deer forages in planted fields were species that established from the seedbank and were not planted. “Our results indicate planting is not necessary to improve habitat quality in old-fields for deer,” said Wade.
The only month of the year when no deer anywhere in Florida are breeding – or at least being caught doing it by the Florida Fish & Wildlife Conservation Commission (FWCC). Deer research biologist Elina Garrison and staff studied conception dates from 580 does across 36 counties for nine years to produce a map of rut peaks across Florida. Peaks fall in every month from July to March, with surprisingly short distances between peaks that are far apart in calendar timing. The reason for the variation isn’t understood well, though early breeding in south Florida is likely related to putting fawns on the ground well before the Everglades flood season.
Number of fawns out of 13 (23 percent of them) that survived to 4 months of age in a broad study of habitat and herd factors on Chattahoochee National Forest WMAs in north Georgia, where deer harvest has declined steadily and drastically for the last 40 years. Declining timber harvests have led to a dominance of mature forest with a scarcity of understory plants that could serve as fawning cover, while black bear populations have climbed and coyotes also appear to be more abundant. Of the 10 fawns that died during the four-month study period, coyotes killed four, black bears ate two (possibly three), and a bobcat killed one. University of Georgia wildlife student Adam Edge won an award for best student poster presentation for these preliminary results of a three-year study that will conclude in 2020.
CWD Species Barrier?
Dr. Brent Race, a staff scientist at the National Institute of Health’s Rocky Mountain Laboratory in Montana, reported that extensive lab efforts were unable to infect cynomolgus macaques – a very close stand-in for humans in disease testing – with chronic wasting disease (CWD). This and other work with “humanized” mice, as well as work at several other laboratories, amounts to strong evidence of a species barrier that prevents humans from contracting CWD by eating the venison of an infected deer. However, Brent said it is important to continue the research and to continue monitoring human health trends in CWD endemic zones, especially older ones like those in Wyoming and Colorado, where it is likely some hunters have unknowingly eaten CWD-infected venison over the years.
“We’re at a point where we’d start to see human cases, and we haven’t,” he said. “Every year that goes by without cases in humans in those CWD endemic zones gives me more comfort, but I can’t say how long we need to wait.”
Brent, a hunter himself, said he would never eat venison from a deer that tested positive for CWD. “I stand by what the CDC (Centers for Disease Control) is saying. In CWD zones, get your deer tested, and do not consume any positive animals.”
To Mow or Not to Mow?
When you mow perennial food plots, are you helping or screwing up? That was the question raised by Bonner Powell of the University of Tennessee in his poster presentation (seen above). Bonner’s research suggests… you’re likely screwing up. Mowing alfalfa, red clover and ladino clover plots routinely throughout the growing season did not improve protein, nutrient content or digestibility of the three forages. It merely reduced the amount of biomass and cover available to deer and other wildlife. Mowing perennials in late summer can be effective to control any problematic broadleaf weeds that may be emerging. Bonner is collecting additional data this year to reinforce his conclusions, but so far significant evidence says that healthy, productive stands of perennials don’t benefit from routine mowing. So, go fishing or mow your lawn if you need to get outdoors this spring and summer, but save fuel and let healthy plots grow!