Doe Management Considerations and Implication
By: Justin Bryan
In the whitetail world, mature does typically give birth to two fawns generally found to be 1 male: 1 female. Yet overall white-tailed deer populations tend to favor females over males. Which begs the question, why is this? One answer is that males naturally have a higher mortality rate than females. Therefore a population would generally be slightly skewed to more females than males. Second is the hunter factor; hunters tend to prefer and more often than not, harvest bucks over does. Taking these two factors into consideration, adult sex ratios in wild deer populations often range from three to ten does per buck. As land/wildlife/deer enthusiasts, why does this concern us, and when is doe management needed?
Late Conception Dates
Research has shown that unbalanced sex ratios lead to late average conception dates and increased breeding season lengths, both of which could have dramatic impacts on fawn survival. Fawns born late in the summer must contend with stress of heat and the declining quality and quantity of available forage, therefore creating the situation where fawns may not receive adequate nutrition in the form of milk from the doe and/or for weaned fawns a lack of nutritious forage in the habitat. As a result, these late-born fawns have difficulty “catching up” with others in their cohort with regards to body development and body condition. This poor body condition may increase susceptibility to disease/parasites/predation/winter kill, lower reproductive potential (rate of pregnancy, recruitment of fawns, delayed estrous cycle) at maturity, and less ability to fully express antler potential later in life. These late-born fawns will always be inferior throughout their life to fawns born earlier in the same year.
Feeding the Hungry
Skewed sex ratios are often related to overpopulation of deer. The average mature doe consumes five pounds of forage per day. If a ranch, farm or property is carrying 20 more does per year than is recommended, that equates to 36,500 pounds of forage being consumed each year that ideally should not be. Therefore, a large forage burden has been placed on the native habitat, which will quickly lead to degradation in the quality and quantity of native forage. Left with poor forage, a deer’s overall body condition declines and in turn hinders survival, estrous cycle, fawn production, fawn growth, and antler production to name a few items. In other words, the overall condition and performance of the deer population is directly related to the quality and quantity of forage available. Those “few extra deer” are like those “few extra pounds on the hips” – each has a negative impact on reaching long-term goals.
Obviously our desire isn’t to suppress our deer herds ability to succeed (healthy does/big fawns/large antlers), so let’s consider the positive impact that can be had by doe management (harvesting the recommended numbers of does).
Getting Doe Management Right
Skewed sex ratios and too many does lead to negative impacts…this is when doe management is called for. Fortunately balanced sex ratios and the correct number of does lead to the positive impacts. These include tighter sex ratios (2F: 1M or 1F: 1M) have proven to shorten the duration of breeding time frame within a population. This tightened duration of rut activity has shown to increase the overall animal activity during the rut cycle, which is especially beneficial to hunters. In addition, a shortened breeding cycle provides the opportunity for the majority of fawns to be born in a shorter time frame which can counter predation impacts. A larger proportion of fawns born early in the fawning season means they have a longer growing period throughout the spring and summer. With adequate forage available, because doe numbers are kept in check, this leads to a better quality of body condition during winter for both adults and fawns. For fawns, being able to maximize growth within the first year sets them up to be able to fully express their genetic potential throughout life.
Doe management is more than simply harvesting does throughout the hunting season. Gathering intel ahead of time via wildlife and deer surveys, and by taking a look at the habitat can insure you are harvesting the correct number and benefiting not only the herd but your habitat and hunting.