Habitat Requirements:
General Concepts
Regardless of area, a thorough knowledge and understanding of the habitat requirements of deer is necessary to accurately assess the quality of deer habitat and predictably manage deer through habitat manipulation. Nearly all habitat requirements deal with one or more of the major habitat components–food, cover, water, and space. Any manageable aspect of deer habitat can be pigeonholed into one or more of these 4 major categories.

While general habitat requirements are universal, specific habitat requirements and how they are fulfilled are not always the same for members of the same species in different areas–hence the need to look at habitat requirements in a regionally specific manner. For example, different populations have adapted to cope with the different environmental conditions with which they are confronted. White-tailed deer in the northern United States have different cover requirements than do deer in our area. Only when these cover requirements are fulfilled, is it possible for northern deer to cope with and survive the severe winters and heavy snowfalls they are often faced with.

Nutritional requirements are a good example of how some requirements, although similar from one area to the next, are fulfilled in a different manner depending upon location. All deer have certain universal nutritional requirements (e.g., some basic amounts of energy and nutrients required per unit of body weight dependent upon certain physiological and environmental conditions). However, the foods that supply the energy and nutrients vary greatly from region to region and sometimes within region depending on availability. Deer are very adaptable animals. If their preferred food supply is depleted, they often can switch to suboptimal foods to survive. Use of suboptimal foods however, if carried to extremes, usually leads to a decrease in herd health and/or numbers.

Whether or not an area is deer habitat depends on whether all of the habitat requirements are met at some threshold level. Beyond this threshold level, habitat quality is determined by the degree to which the habitat fulfills the needs of the animal, in terms of both quality and abundance. Habitat quality is often expressed in terms of condition class–i.e., poor, fair, good, excellent. It is important to emphasize that habitat is only as good as its most limiting aspect. This "limiting factor" concept is an important part of evaluating and managing deer habitat.

The following scenario is a simplified example of the limiting factor concept. Suppose an area is judged to have excellent space characteristics, a fair food supply, good cover, and excellent water distribution. Even though the other habitat components are in good to excellent condition, the food component is less than optimal and prevents the hypothetical deer herd from fully utilizing the space, cover, and water resources. The end result is a deer herd that is limited in quality and/or quantity by the food supply. Through management, it is possible to make food less limiting and pave the way for herd improvements in terms of quantity and/or quality. It is even possible to improve the food component to the point where it is no longer limiting. In such a case, some other aspect of habitat will become limiting. If it is in accordance with the goals, management efforts should then be directed to address the new limiting factor, which in this scenario would be cover. One of the keys to successful management is being able to identify and improve limiting factors.