Current Deer Management
November 04, 2010
By Dr. Dave Samuel, Conservation Editor
"DAVE, THE RUT HASN'T kicked in here yet, so tomorrow we'll hunt up north," George said. "Up north" meant another property he owned 20 miles away.
"George, I don't understand. If they aren't rutting here, they won't be rutting 20 miles north."
"Oh, yes they will, Dave. They rut 2 weeks earlier up there," George responded.
I was on a December bowhunt with my good friend George Mann near Opelika, Alabama. Different rut times on areas that were only 20 miles apart sounded crazy to me, but I'd soon discover it was true. For a good old West Virginia boy, this was unheard of. Back home the peak of the rut is always November 10-15. Sure, the intensity might vary with the weather, but the peak was the same for the whole state - and for adjacent states as well. That isn't always the case in parts of the South. It wasn't until one year after my hunt with George, at the Southeast Deer Study Group meeting, that I learned why some adjacent deer herds in the South have different rut dates.
Mississippi State and Texas A&M University researchers examined the genetics of 13 adjacent deer populations in Louisiana and Mississippi among which the rut periods differed by an average of 28 days. For a control, they examined adjacent deer herds among which rut times did not differ. Herd composition (i.e., buck to doe ratios) can impact the timing and length of the rut, but harvest strategies and subsequent herd composition were similar on all sites.
What did these scientists find? In some areas of the South, as long as 70 years ago, because deer numbers were low, herds were supplemented with stocked animals. The conclusion of the research was that these stocked deer brought in different genetic characteristics that affect the timing of the rut today. In other words, genetics has led to different rut times in adjacent herds.
This study was just one of the many reported on at the 26th Southeast Deer Study Group meeting held in February in Chattanooga, Tennessee. What follows are summaries of some of the other papers presented at that meeting.
Making Big Bucks
Texas - Researchers at the Caesar Kleberg Wildlife Research Institute reported the results of their study on antler growth in South Texas deer. There were two objectives: 1) To determine the potential antler growth of spikes and forkhorns as they age; 2) To determine the impact of spring rains on antler growth.
When yearling spikes and forkhorns reached 3 years of age, their antlers caught up in size to those of bucks that were larger as yearlings, and that was in all aspects: points, circumference, inside spread, beam length, and gross score. These data suggest that we should let spikes age, because they have the potential to develop into good bucks.
The issue of rainfall in relation to antler growth wasn't as clear cut. Rain/antler relationships appear to be rather complicated in Texas. For example, the researchers found that high rainfall in June/July and October/November led to larger antlers the following year. Even so, the researchers indicated that they need to study the issue further before they can conclusively link abundant rainfall in general with larger antlers. Here's one last gem from this study: Antler size peaked at 6 Ã‚½ years of age and began to decline at 8 Ã‚½ years of age.
West Virginia - Researchers at the University of Georgia looked at ways to reduce the harvest of yearling bucks in order to get more 2 Ã‚½ year olds in an area. Their approach was simple - go to a remote, 8,400-acre area of West Virginia that has 36 deer per square mile and is heavily hunted. Put a gate up on the only access road to restrict hunter access, and then put radio collars on yearling deer to see if the access restriction would reduce harvest.
It is a well-documented fact that some yearling bucks leave the area where they were born while others do not. The study in West Virginia was set up to determine whether bucks that migrate from an area survive at different rates from those that don't - and to determine the effects of restricted access.
Researchers radio-collared 24 yearling bucks, of which 15 migrated out of the area and 9 stayed. The average distance of those that migrated was 4.4 miles, but one energetic buck traveled 12.8 miles. That's a long way in the rough, steep terrain of West Virginia.
Eleven of the 15 bucks that left their home area were killed by hunters as yearlings, and three more were killed the next fall. Of the nine bucks that stayed on the gated area, four were harvested the first year. Only three lived to their second year and two of those were shot in that second year. So, of the 24 yearling bucks, only two lived beyond 2 years of age. The conclusion reached was that locking gates in West Virginia (i.e. reducing hunter access) is not a guaranteed way to increase the survival rate of yearling bucks.
Georgia - In 1993 Georgia became the first state to impose Quality Deer Management (QDM) antler restrictions throughout a whole county. Subsequently, three other counties adopted antler restrictions. But research was needed to determine if the approach was working, so in 1998 the Georgia Department of Natural Resources radio-collared 135 bucks in parts of four counties to assess mortality. In two counties the antler restriction was 15 inches outside spread (ear tip-to-ear tip), and in the other two counties the antler restriction requirement was 4 points on one side.
In the areas with 15-inch spread minimums, 57 percent of all yearlings survived to 2 Ã‚½ years of age, and 25 percent survived to 3 Ã‚½ years of age. In the 4-point-or-better areas, 47 percent of all yearlings survived to age 2 Ã‚½, and 29 percent survived to age 3 Ã‚½. Also, twice as many yearling bucks were killed illegally in the 4-point areas than in the spread-restrictions areas.
Does QDM work on a countywide basis in Georgia? It depends on your perspective. In Georgia counties under QDM, 50 to 60 percent of all yearling bucks lived to be at least 2 years old. Will the increase in 2-year-old bucks stimulate hunters to obey restrictive rules and to support the QDM concept? Only time will tell.
What Big Bucks Do
Several Texas researchers reported on a study that answers two age-old questions: 1) Do older bucks play a greater role than younger bucks in breeding does? 2) Does antler size have anything to do with reproductive success? Truth is, up until this study, many of us have suspected that older bucks (and bigger-antlered bucks in general) do most of the mating. However, this study yielded some surprising results.
Bucks fitting into four categories were captured in the wild: high-quality bucks (antlers measuring greater than 120 inches); low-quality bucks (antlers measuring less than 90 inches); young bucks (1 Ã‚½ years old); an
d older bucks (4 Ã‚½ years of age or older). Bucks from all categories, along with some wild-captured does, were placed in two 500-acre pens. All deer were tagged, and then DNA samples were taken so that the parents of all offspring could be identified.
The first finding confirmed something I reported in "Deer Management 2002" - twin fawns sometimes have different fathers. In this study, 8 of 37 sets of twin fawns had different fathers.
Did older bucks do a higher percentage of the breeding than yearling bucks? Yes, but not by much. In fact, in one of the pens yearling bucks did 45 percent of all breeding. In that same pen, one 10-point buck with antlers measuring 150 inches didn't breed any does at all. Nor did a 4-year-old buck with low-quality antlers.
However, quite a few so-called low-quality bucks did breed does, and one mediocre buck propagated far more than his share of offspring. That buck had a rack only scoring 126 inches, but he bred 16 of 26 does in one of the pens.
The researchers concluded that the reproductive system in whitetails is more complex than we once thought. Indeed we have to ask why a few older, larger bucks don't participate in breeding at all, while some younger bucks carry out a high percentage of the breeding?
These are interesting questions that just might be answered at next year's Southeast Deer Study Group meeting. When that happens, Bowhunter Magazine will bring you the answers.