Thursday, March 12, 2015

Getting Deer through Winter

During winters like the one we just experienced, many of us feel the need to feed deer, but deer biologists discourage it for many reasons. Decades of research has clearly shown that supplemental feeding leads to increased risk of disease, long-term habitat destruction, habituation to humans, alteration of other deer behavioral patterns, and the demise of the value of deer and deer-related recreation (PA Game Commission 2012). With Chronic Wasting Disease now present in the state, the increased risk of disease transmission from concentrated feeding activities is one of the most significant reasons not to feed.

Deer are extremely well-adapted animals and in general don’t need supplemental winter food. Deer
eat very little in winter, getting by on what natural foods are available. In good habitat deer enter winter with 2-3 months of fat reserves and conserve energy by lying up during severe weather. In fact, feeding deer may lure them away from natural wintering areas, increasing energy loss. In addition, it can take up to four weeks of feeding on a new food source for deer to establish the microorganisms in their stomach necessary to obtain nutrients from that food. Studies in Pennsylvania have documented the death of wild ruminants from supplemental feeding in winter, a condition known as rumen acidosis.

So what is a concerned landowner or hunter to do? Act like a logger and fire up the chainsaw! Loggers in Pennsylvania are no strangers to feeding deer. Their crews feed deer every day. Not with corn or bales of hay, but with mechanized tree cutters and chainsaws. Once the tree hits the ground deer have access to the tender buds and twigs, called browse, which are generally nipped off within a matter of weeks. Where there are chainsaws, there's browse.

Stump sprouts browsed by deer
Deer are referred to as “browsers” meaning twigs, buds, and leaves of trees and shrubs make up a primary component of their diet. A deer’s system can easily digest woody browse, and they will feed on it year round. It is the most important source of deer nutrition. During winter and early spring it is especially important as most other food sources are unavailable. Deer depend on browse to get them through the winter months.

Studies have shown that deer are selective feeders and have distinct foraging preferences. Preferred foods are eaten first, marginal foods are eaten only after preferred foods become scarce, and starvation foods, those that have little nutritional value, are eaten when no other choices are available. In Pennsylvania, work compiled by the Bureau of Forestry and others has shown that blackgum, oak, basswood, maple, tulip poplar, aspen, hickory, ash, and pin cherry provide preferred browse. Of the shrubs, dogwood, viburnum, elderberry, hawthorn, winterberry, sassafras, and raspberry briars are preferred browse.

On average a deer will consume one ton of forage annually. Only the preferred species of small trees, shrubs, and plants have the ability to support large numbers of deer in principally wooded habitats, but it must be present in large quantities. A mature forest provides far less browse than the young brushy stage that occurs shortly after logging. Mature forests only produce 50-100 pounds of browse per acre while young forests, known as early successional habitat, can produce 1,000-2,000 pounds of browse per acre (QDMA,Whitetail Report 2009). Mature forests are important for providing hard and soft mast, such as nuts and fruit, but deer need a variety of habitat types and a diversity of tree age classes. What may have been good deer habitat 15 years ago is probably poor habitat today.

Recently thinned 30 year old woodlot
All deer habitat management should revolve around a forest cutting program to create additional woody browse. One important practice is to thin overcrowded trees. This is a great practice to do in woodlots that are still relatively young, from age 15 to 50 years of age. The purpose of thinning is to free desirable trees from neighboring trees competing with it for growing space. Trees can be thinned to a more desirable spacing by removing poor quality and less desirable species. Thinning trees in winter will puts tops on the ground that deer can browse on during lean times. Thinning overcrowded trees also increases the amount of sunlight reaching the forest floor. This provides ideal conditions for new seedlings and sprouts to get started. An added benefit of thinning overcrowded trees is that it improves the overall health and condition of the woodlot and concentrates growth on the remaining trees.

Another deer habitat management practice that should be utilized to increase the amount of woody
Regeneration harvest in second growing season
browse is to cut and regenerate mature forests, referred to as a regeneration harvest. In this case, a new forest is started from seedlings and sprouts. There are a number of recommended practices utilized by foresters to regenerate mature forests so be sure to consult with a forestry professional before proceeding. Regeneration harvests will provide an abundance of herbaceous vegetation and new succulent sprouts that will flourish in the full sunlight following cutting. This new growth will not only provide an abundance of browse but will also provide concealment for a long period of time, even after the browse has grown out of the deer’s reach. A word of caution, in many areas deer populations exceed the carrying capacity of the habitat and regeneration failures can occur in those areas. It may be necessary to first reduce the deer population in an area before implementing a regeneration harvest.

This winter has provided us with a tough lesson. Take action today, consult with a forestry professional and make a plan to create some additional woody browse on your property or favorite hunting area. Deer and many other wildlife species will prosper all winter from your efforts.

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