A recent DNA buck study done at Chesapeake Farms, located on the eastern shore of Maryland, calls many deer management practices into question. (Note that quality deer management has been practiced on this farm for many years.)
According to the study, even though 3½-year-old bucks comprised more than half of the bucks in the area and did 41 percent of the breeding, yearling bucks did 23 percent of the breeding. Even more, the 2½-year-olds did 36 percent of the breeding. This is surprising because previous studies have shown that 3½-year-old bucks do most of the breeding. Additionally, studies from Texas and Oklahoma showed 1½ and 2½-year-old bucks did around 20 to 30 percent of the mating. At 59 percent, this Maryland study doubled that.
So, although many wildlife biologists and deer-management experts have believed the older, bigger buck did most of the mating, we now know that is not true, at least not in this situation where we know Quality Deer Management (QDM) was practiced. Even though QDM yielded lots of older bucks, the young guys still did over half of the mating.
Does That Mean QDM Doesn’t Work?
It’s easy to understand how young bucks mate does when a property has a high doe ratio. In those situations, there are just too many does for the older bucks to mate. But this rationale doesn’t answer why more than half the mating on Chesapeake Farms was done by young bucks. This was a habitat with a balanced sex ratio.
Yet, there is one obvious reason: turns out that most does at Chesapeake Farms are bred in the November rut. With equal sex ratios, older bucks couldn’t dominate breeding. And given the short length of the rut, it just wasn’t possible for the older bucks to get all the does mated.
Since a dominant buck stays with (or tends) a hot doe for several days, this restricts the number of does he can mate and opens the door for mating by younger bucks with lesser antlers.
(Note: These young bucks may have good antler potential, but it just hasn’t been fully expressed because of age.)
Leaders in deer management practices have largely believed mating done by younger bucks is a bad thing, but maybe not. Maybe there isn’t an evolutionary benefit for all mating to be limited to older, mature bucks. With only so many does out there, older bucks would have to expend a huge amount of energy to breed them all. Just protecting the does would require the older bucks to run around fighting and competing, which might wear them down more than it already does.
Potential Threats to The Herd
Relative to getting better bucks, keeping your yearlings is a good thing. But what about inbreeding? While it’s often thought that high yearling dispersal helps genetic variability, with QDM many yearlings stay home. Does this combination create a potential inbreeding problem?
Maybe. But 63 percent of all mature bucks at Chesapeake Farms expended energy to make at least one excursion out of their home range before and during the breeding season, and some made more. Why? The authors of the study believe breeding was involved. Additionally, 90 percent of the does made excursions out of their home range during that same time frame. This means that potential sires and mates are moving all over the landscape and getting bred as a result. This possibly yields higher genetic variability in the resulting offspring.
Antler-wise, there are still a lot of good bucks on Chesapeake Farms. Younger bucks mating often isn’t a problem. If the strongest, healthiest younger bucks are doing the mating, then the fawns produced should also reflect that. And, apparently, they do.
Given the findings in the Maryland, when there is equal sex ratios and hunters don’t harvest yearlings, the 1- and 2-year-old bucks mate over half the available does. If your goal is to propagate the genes of older, dominant bucks, QDM may not be what you’re looking for. However, the results from the Chesapeake Farms study show that practicing QDM improves your chances to see and take mature bucks, while improving the overall health of the herd and the habitat.
For tips to grow bigger bucks with trophy-caliber antlers, read “Does Improving Herd Genetics Actually Grow Bigger Bucks?”