Post-Rut Mortality And Fawn Recruitment
In winter, with hunting season drawing to a close and waiting for spring, many ranch managers tend to step back and take a breather after the busy season to reflect and recharge. Deer, however, are in one of the toughest and most nutritionally demanding periods that they will undergo during the year. The next 60 days are when the majority of bucks are lost to post rut stress, and when fawns will succumb to poor nutrition.
Post-rut Mortality
With current feed prices, many managers want to get the most “bang for their buck” and will often not want to start feeding until antlers drop and new ones start to grow (typically in March or April). Basically, they want to go into a holding pattern for a few months and hope the deer are able to cruise to the spring without having to supplement. What is often overlooked is the fact that some properties will lose as much as 80% of their bucks, and 50% of their fawns, due to malnutrition and post rut stress during this time.
While most managers believe that bucks lost are coming out of the mature age class, current research has pointed out that bucks in the young to middle age class are often hit harder than the mature age category. This poses a major problem if a great 3.5 year old has been protected all season, only to lose him to post rut stress after the season is over.
It is important to realize that although the nutritional demands of whitetail deer are at maintenance levels, many bucks have lost as much as 30% of their body condition, due to the rut. For all but the most diverse habitats in good years, it is not realistic to expect weaned fawns or bucks that are in extremely poor body condition and stressed to survive, much less rebuild depleted body condition, without some type of supplementation.
For those concerned with antler quality, it is important to remember that deer will start applying nutrition towards new antler development as soon as they drop their old set, provided they are in good body condition. However, if deer are in poor body condition, everything they take in will be put toward replenishing depleted body mass, not towards growing antlers. This will automatically put a buck behind the antler growth curve and equate to smaller antlers this coming fall, regardless of what that deer is genetically capable of growing. Basically put, body condition will always take precedence over antler development. Providing a supplement all winter will not eliminate the loss of some body condition, however if it is a palatable, well-balanced diet, they will still utilize it as a portion of their diet. Although requirements have lightened from a protein standpoint, managers have to be careful in what they are feeding as deer are much more sensitive nutritionally when they are stressed.
Many managers will often look at their deer and feel they are in adequate body condition, and often not want to provide a free choice supplement until they know deer are growing their antlers. While providing a balanced free choice supplement during antler growth will improve quality, the months of January and February can often be more nutritionally influential, as far as antler quality is concerned. Anything we can do to improve their nutrition intake will boost the amount of nutrients bucks have available to apply towards antler growth. Bucks pull the majority of the nutrients and mineral from their long bones when they are growing antlers due to the fact they can’t physically take in enough nutrition to keep up with antler growth. Our main goal during this time should be to fill the reservoir they are pulling these nutrients from, before they begin their new antler cycle.
Fawn Recruitment
The other major problem for most ranches during this period is with fawn attrition. How properties are managed during the next 60 days will often be what determines fawn recruitment. Even if a ranch is lucky enough to have a 100% fawn crop, on average as much as 50% of a buck fawn crop is lost during this time to malnutrition or predation. Fawn recruitment will benefit exponentially if fawns have access to supplemental feed at this time.
Improving the nutrition available for these deer will pay dividends down the road as well. We are not only going to improve recruitment, we are ultimately going to be improving a bucks antlers when they are mature by improving the nutritional plane available when they were young. Regardless of their genetics, the better they are fed during their young and middle age classes (birth through 4.5 years), the bigger their antlers will be at maturity.
When offering free choice pelleted rations, it is imperative to note that most commercial pelleted deer protein supplements that are available consist of at least 30% starch due to high grain inclusions. If a deer that has lost 30% of its body condition is offered free choice grain, or a deer supplement that has a high starch level, they will most likely become acidotic. When combined with stress, mortality is the result. Remember to offer a supplement that is balanced to promote rumen health and will complement, not substitute for, your native habitat.
Ranchers and land owners work too hard improving habitat and managing herds to grow quality deer, only to lose half of the bucks and fawns to malnutrition and post rut stress. Offering a balanced free choice pelleted supplement that is available for all deer during this important time of year is often the management decision made by ranches that have exceptional antler quality and recruitment year in and year out. With current feed prices it is important to know that what is provided to deer is not doing more harm than good, as stressed bucks are extremely sensitive nutritionally.
If you would like to learn more about supplemental feed, or discuss your current feeding program, please contact us on our website or Facebook page.