Seasonal habitat requirements of southern white-tailed deer
By Matt Ross, Whitetail Stewards, Inc.
Food
Spring
Much like in northern regions, deer in the south rely heavily on green forbs and grasses in the early spring. However, the dietary proportion of each forage depends greatly on climate and geographic range; southeastern deer generally have access to more forbs, whereas deer living in Texas or the southern plains states consume more grasses. Overall, 90% of the spring diet of southern deer can be comprised of herbaceous plants; forbs typically make up the highest proportion (23-68%), followed by grasses (8-58%), cacti when available(18-21%), and browse (5%). Agricultural plants, such as corn, sorghum, soybeans, lespedeza and clover, are also used extremely heavily (40-50%) when available.
During the summer months, southern deer instinctively consume new tender shoots, leaves and twigs of trees, fungi, shrubs and vines, and many different kinds of broad-leafed herbaceous plants. Deer in the southeast typically have access to ample amounts of succulent vegetation. In especially arid regions, although summer foods tend to be 1.5 times more digestible than winter foods, nutrient levels may fluctuate and the quality and quantity of forage produced by local plant communities may be grossly inadequate as a result of a reduction in rainfall. In fact, during severe drought conditions it has been documented that certain plant species may be eliminated over extended periods of concentrated grazing pressure and, consequently, local deer populations suffer.
In autumn, southern deer begin to focus less on herbaceous food sources and concentrate their feeding efforts on ripened soft and hard mast. When available, acorns, are by far the most preferred food item to deer and many other wildlife species (including several species of insect) across the south. Even during years of low acorn production, acorns still manage to comprise a minimum of 15-20% of an individual deer's diet, and at times, may represent over 50% of the total amount of food a deer consumes each day. In areas that lack the presence of mast bearing tree species (e.g., oak, beech), deer maintain diets that consist mainly of browse, grasses, forbs, and mushrooms (1%).
Between January and April, when green forage is scarce, most southern deer will consume browse, any remaining mast, and perennial plants that remain green during winter. However, a study in south Texas reported that some deer had an affinity towards available grasses and forbs during this time period, with consumption rates of each peaking in February. Regardless, general observations indicate that deer in the south will consume preferred grasses and forbs when available, and rely on browse throughout the year.
In the south, excessive heat and lack of rain during summer months force deer, livestock, and other animals to congregate around and exist on limited water supplies. This seasonal concentration of deer can be extremely detrimental to the herd's health; disease prevalence in the south can create conditions where neurological disorder and parasite infestations are spread easily between waterhole visitors.
In areas where mosquitoes and biting flies are abundant, deer will attempt to escape the irritating bites by partially submerging themselves in standing water. Southern deer will also use water to confuse predators or trailing hounds by diluting their scent trail.
Cover
In the south, deer cover requirements are minimal compared to those of whitetails in northern regions. Areas that severely lack suitable cover tend to be either large tracts of forest that have been recently clearcut or places where brush has been cleared to favor grassland habitat. Mostly, southern deer seek areas of dense, low-level shelter for two reasons, to escape predators and to access available food sources. Southwestern deer also choose these areas because they provide quality cover from the sun; shade is especially critical in areas where mid-day temperatures elevate to dangerously high levels. In the southern plains region, stream courses provide the primary means of quality cover for deer, and can be the limiting factor for local populations. When crops are available, such as standing corn, deer may rely both on stream beds and farmland.
Under dry summer conditions, whitetails tend to move closer to a permanent water source, only to disperse once the autumn rains start. Large numbers of deer are likely to be found feeding on the only available lush vegetation in open sandy sites, dry lakebeds, and areas where brush has been removed. Following occasional summer rain events, vegetation growing on sandy soils responds quickly to improved moisture levels with new growth. Green vegetation persists for longer time periods in natural depressions, such as dry lakebeds, than on surrounding upland sites. In areas that receive mechanical brush-control treatments, early-successional vegetation (forbs and grasses) is continually available.
Space
Carrying capacity is directly related to forage availability. White-tailed deer in the south, particularly in Texas, readily compete with goats, sheep, and cattle for browse, mast and forbs. Deer populations in these areas have also historically been too high for the land (as many as 50 deer/square mile), and have been drastically under-harvested for decades. Browsing from all of these animals impacts deer habitat and spatial requirements. Deer in these areas are typically forced into relatively small home ranges. Conversely, white-tailed deer populations in the southern plains states (Oklahoma, Kansas, Colorado, New Mexico) have a limited distribution and typically do not reach biological carrying capacity (in certain areas, 1.2 deer/square mile). In these places, depending on the presence/absence of mule deer, home ranges tend to be much larger, with daily movements ranging 5-22 miles.
Seasonal movements of southern deer have also been noted to occur. Although not entirely considered to be migratory in nature, deer in North Carolina, Arizona, Georgia and Florida have shown abilities to move in response of food, water, and cover availability and hunting pressure. Movements in response to flooding and drought condition are also common.
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