For the past two years, NDA was proud to voluntarily coordinate and host the largest national gathering of deer researchers, the Southeast Deer Study Group meeting, to ensure its continuation despite the pandemic. It’s fortunate a virtual option was available during the pandemic, because deer research did not stop, and there has been some fantastic work reported in these two years. After attending the 2022 meeting, I prepared a snapshot overview of some of the coolest and most useful new information.
Here are 14 statistics and terms from new deer research that caught my eye. There’s a little something here for every deer hunter, from hunting strategy to habitat management, coyotes to conservation.
Average number of home-range shifts per year for GPS-collared bucks that exhibited “mobile” personalities, meaning they had multiple, seasonal home-range compartments and moved back and forth between them (compared to “sedentary” bucks that had a single home range). Luke Resop of Mississippi State University’s Deer Lab analyzed the movements of 30 GPS-collared adult bucks and found 20 of them (68%) were sedentary and 10 were mobile. The average distance between distinct home-range compartments for mobile bucks was 4.4 miles! Mobile buck behavior likely explains some of those vanishing acts that bucks often pull on us.
Amount spent in 2020 alone by deer hunters in 15 Southeastern states to pay for “plantings and food plots for deer hunting.” Their total expenditures generated $100 million for conservation through the Pittman-Roberston Act. The meeting theme this year was “The Value of Deer and Deer Hunting to the American Public,” and to go with that theme, NDA presented some results from Phase 1 of the Southeast Deer Partnership project. Mark Duda, executive director of Responsive Management who gathered this data, shared it in his talk on the value of white-tailed deer to Americans.
An estimate of the heritability of antler traits, which is similar to expressing the likelihood that a large-antlered buck will produce fawns that grow up to have large antlers also. In other words, it’s a weak relationship, therefore “culling” of bucks based on antler size isn’t likely to improve antler size of future bucks. Cole Anderson of the Caeser Kleberg Wildlife Research Institute at Texas A&M-Kingsville is continuing to gather data to hopefully determine how much other factors play a role in antler size, such as habitat quality, life experiences, and the genetics of a fawn’s mother.
Average rating of the importance of properly managing and conserving deer in a person’s home state, on a scale of 0 (not at all important) to 10 (extremely important). This was a question in a survey conducted by Responsive Management as part of the Southeast Deer Partnership. This question was answered by 819 members of the general public and goes hand-in-hand with other surveys that have shown strong public support for deer hunting.
Proportion of the total fall white oak acorn crop that fell during one week (Thanksgiving week) at a Georgia study site. See the graph below. Kelsey Demeny of the University of Florida Deer Lab set up acorn traps under 215 oak trees, including laurel, water, white and swamp chestnut oaks. White oaks dropped acorns heavily over a short period of time, while all other oaks dropped over a longer period throughout November and December. However, trail-cameras deployed under some of the trees showed that deer use of white oaks actually dipped significantly when acorns were falling heaviest, likely due to hunting pressure. Deer hunting began the week before Thanksgiving on the study site. Kelsey won 2nd place in the poster competition for this study.
5½ to 6½ years
Peak age for doe fertility, after which it begins to decline, based on 13 years worth of fawn production data for deer living in Auburn University’s 477-acre fenced research facility in Alabama. Tristan Swartout of Auburn analyzed genetic data and reproductive history for 156 does. He classified 47% of does in the population as “consecutive recruiters,” meaning they recruited a fawn or fawns for two straight years at least once in their lifetime. These consecutive recruiters produced 75% of all fawns that survived to 6 months of age, which is the definition of “recruitment.” One doe recruited fawns for seven consecutive seasons. These findings suggest that a small percentage of does are naturally gifted mothers and are responsible for the majority of fawn recruitment.
The proportion of surveyed Americans who strongly (60%) and moderately (22%) approve of legal, regulated deer hunting. Compare this to 9% who disapprove – 3% moderately and 6% strongly. NDA’s own Kip Adams presented these results from the Southeast Deer Partnership project aiming to improve public understanding of the value of deer.
4 to 14 days
Range of time delays between a coyote’s return visits to areas of repeated use within its territory. Though 41 GPS-collared coyotes in three southeastern states were constantly roaming, GPS data revealed hot-spots within each territority that were revisited regularly at night. It’s assumed these hot-spots are prime hunting areas, and coyotes appear to give these spots several days “break” between hunting them. Jordan Youngmann of the University of Georgia presented this study as well as another analyzing coyote scat contents, and he took second and third place for best student presentation with these talks.
Reduction in deer use of perennial food plots in the week after application of the herbicides clethodim (12 oz/acre) and imazethapyr (4 oz/acre) compared to control plots that were not sprayed. In the second week, deer use returned to the same level in both sprayed and unsprayed plots. Lindsey Phillips of the University of Tennessee used trail-cameras to monitor deer use of four test plots averaging 2.5 acres each, each divided in half, with only one half of each plot being sprayed in mid-October to control cool-season forb and grass weeds. Deer use was the same in each half for one month pre-treatment and, except for the 67% dip in use of sprayed areas for a week following spraying, remained the same in the month post-treatment. Lindsey won the award for best student poster presentation with this study – her third time winning this award at Southeast Deer Study Group.
The greatest risk factor for fawns in their first 21 days of life, meaning that the more often a doe visits her fawn at night, the more likely the fawn is to die. Mike Muthersbaugh of Clemson University tracked the movements of 49 fawns and, separately, the movements of their mothers at a South Carolina study site; 70% of the fawns died before September, with coyotes being the cause of death for the majority. The fawns that survived tended to have mothers who kept a greater distance from their fawns when apart but who also visited the fawns more times per day – as long as those visits were in daylight. Does that visited their fawns at night, when coyotes are more active, dramatically increased their fawns’ chances of dying.
The proportion of 35 species of forbs (broad-leaved forage plants) that contained crude protein, calcium and phosphorus at levels meeting the minimum nutritional needs of a doe nursing fawns. The other 56% did not meet the phosphorus requirements. Mark Turner of the University of Tennessee collected samples from forbs, semiwoody and woody forage species from sites in four southeastern states, including old and young parts of each plant. Some examples that consistently met all three criteria across all these sites were common ragweed, Desmodium species (such as beggar lice), and horseweed. Mark said this emphasizes the need to encourage more forb biomass but also forb species diversity through habitat management to help deer meet nutritional needs.
Round-trip distance of an excursion by two mule deer does being tracked by Calvin Ellis of the Caesar Kleberg Wildlife Research Institute at Texas A&M-Kingsville. This was the longest excursion movement (outside the normal home range) seen among 30 GPS-collared juvenile mule deer in a newly established CWD containment zone in the Texas panhandle, along the Canadian River. So far, just over a fourth of the collared deer have made a dispersal or exploratory movement, demonstrating the potential for spread of CWD across long distances through natural movements.
Ranking of Lauderdale County out of all the counties in Alabama for risk of CWD introduction to the state. In fact, Lauderdale became the first county in Alabama where CWD was detected. The predictive ranking was produced by the Surveillance Optimization Project for Chronic Wasting Disease (SOP4CWD), which uses computer-based models developed by Cornell University’s Wildlife Health Lab to evaluate a number of risk factors to help state wildlife agencies predict introduction and monitor spread of CWD. Krysten Schuler of Cornell covered the program’s current and future capabilities.
Ambient air temperature at which captive research deer began to choose higher-quality shade. Just as deer must burn energy to stay warm in winter, they must also burn energy when using physiological processes that help keep them cool in summer. The hotter the weather, the more energy deer burn staying cool, so the quality and quantity of shade plays a role in herd health, especially in the southwest. Jacob Dykes of the Caesar Kleberg Wildlife Research Institute at Texas A&M-Kingsville set up holding pens with varying percentages of shade using overhead “shade cloth.” Though summer temps averaged 96° F and highs at the site reached 117°, deer were seeking the highest-quality shade to help minimize energy loss long before those temperatures were reached. Jacob is now studying natural settings to see how shade, air flow, and other factors create the most desirable heat refuge for deer.