Balanced Deer Herd is Healthier

MONTGOMERY-Much has been written about the need for an adequate doe harvest when managing deer populations. Most experienced deer hunters realize they must kill some does each year to keep the deer herd within the habitat’s carrying capacity and in good health. Yet most hunters have no idea how important a balanced adult sex ratio is to maintaining the deer herd’s overall health.
What is a balanced sex ratio? Sex ratio, or more specifically the adult sex ratio, refers to the ratio of adult does to antlered bucks in the population. In general, bucks and does are born at a 1-to-1 ratio, but bucks tend to have a slightly higher natural mortality rate than does due primarily to deaths resulting from rutting behavior (e.g., fighting, increased travel, etc.) and fawn/yearling dispersal. Even with this added mortality, the adult sex ratio in a “natural” deer herd should be fairly even or only slightly weighted toward does (e.g., 1.0 – 2.0 adult does to 1.0 antlered buck). In intensively managed herds where does are heavily harvested and bucks are allowed to reach maturity (i.e., 4 1/2 years old and older), the adult sex ratio can be weighted toward antlered bucks. On the other hand, populations with a history of heavy buck-only harvest will most likely be heavily skewed toward does (e.g., 4.0 or more does to 1.0 antlered buck).
A balanced sex ratio has many advantages. One of the most important is the length of the breeding season, or rut. In a deer herd with a balanced number of does and antlered bucks, nearly all does will be bred during their first estrous, usually over a very short period of about two weeks. On the other hand, does in an unbalanced herd will have to “recycle” and will be bred over a two- to three-month period, or even longer. One of the advantages of having breeding occur over a short period is so that most fawns are born within a couple of weeks of each other. For buck fawns, this means each will have the same length of time to grow and develop antlers during their first year as other bucks born that year. Very few late-born fawns will have to play catch-up during their first couple of years.
Another advantage to having a shorter rut is the bucks do not spend three or four months chasing does and breeding. Instead, they participate in a very brief and intense breeding period that lasts only a few weeks. After the majority of does have been bred, the bucks can rest, feed and recuperate from the rigors of the rut. These bucks have a shorter recovery time, so they can put more resources toward body and antler growth earlier in the spring and summer. Bucks that have to participate in a prolonged rut (e.g., three or more months) do not have the luxury of this recovery time. In many situations, bucks are spending all of their time trying to breed unbred does well into late winter. These bucks must put a large portion of their food intake during the late spring and early summer into recovering from the previous rut, instead of into developing bigger bodies and antlers.
One advantage of a balanced sex ratio that is not often discussed is the timing of the rut. Not only does the rut become shorter in balanced herds, but many times the peak of the rut is actually moved earlier in the year by as much as 4 to 6 weeks. This is important primarily because of the timing of fawn births. If a fawn is born 4 or 6 weeks earlier, its chances of surviving and developing to its potential are much improved. This is especially important in areas such as Alabama where most does are bred in mid- to late-January and fawns are born in August or September. By moving the rut earlier through intensive herd management (i.e., shooting does, protecting bucks), fawns can be born as early as late June or July. Food is more plentiful at this time of year so their mothers are in better shape and should be able to raise healthier fawns. It also gives the fawn additional time to grow during their first year, which gets them off to a better start in life.
From a hunter’s standpoint, other benefits of a balanced sex ratio and more intense rut are the types of hunting tactics that can be effectively used and the amount of rutting sign/activity typically seen. Tactics such as rattling, calling with grunt tubes and scrape hunting are much more productive in herds with balanced sex ratios due to the increased competition among bucks for breeding privileges. Scraping, rubbing and chasing activity during the rut are much more common in balanced herds. Instead of the occasional small scrape, pencil-sized rub, and a single yearling buck trailing a doe in heat, scrapes the size of car hoods, rubs as large as a man’s leg, and several adult bucks chasing an estrous doe become fairly common sights in well-balanced herds.
The solution for correcting an unbalanced sex ratio is simple: kill more does and shoot fewer bucks. Removing does helps reduce yearling buck dispersal, and protecting more antlered bucks allows more deer to reach the adult age classes (31/2 years old and older).
Hunters must remember that correcting something that took years to create will not occur overnight. This type of deer management takes continual commitment from everyone involved, but the results are well worth the effort.