Habitat is comprised of the things organisms need to survive. In the context of animals, this is:

Food

 

Foodstuffs vary over the course of a year, with the period of the poorest food availability limiting the number of animals that a parcel can support.

 

Water

 

Water is necessary for life. The way animals obtain and use water varies from species to species.

 

Shelter

Shelter includes bedding locations, places animals minimize risk due to adverse weather, and places that afford cover to avoid predation.

 

Space

Space contains the previously mentioned items: food, water, and shelter. If the space is not sufficient to contain enough food and water, and there is not enough land to claim breeding territory, then the number of animals that a parcel can support will be limited.

 

Arrangement

Arrangement connects all these elements together. Deer prefer to travel between bedding areas and feeding areas under cover, taking advantage of depressions in the landscape, saddles, small folds or ditches, and brush. Such corridors can funnel deer movement. Without travel corridors connecting necessary elements of habitat, the parcel will not be suitable for the species. The needs deer have for travel corridors is different from those of squirrels or of birds.

The number of animals a parcel can support throughout the year is called "carrying capacity." Some properties are small enough that they do not contain all the elements required to sustain a population of animals, yet comprise a part of such a parcel. [Photo courtesy of John Corrao of QDM Association]

The way species use their habitat determines how we hunt them. Ruminants are capable of digesting cellulose -- indirectly. No animal produces the enzymes necessary to digest cellulose. Ruminants, which have 4-part stomachs, provide stomach partitions that are friendly to bacteria that can digest cellulose. Then the other stomach partitions can digest the bacteria and extract the nutrients that way. This implies they can pick up lots of food quickly, bed down, and process that meal. Movement between feeding areas and bedding areas implies use of arrangement.

Breeding behavior almost always involves the claiming and use of territory. For deer, this involves marking territory with rubs and scrapes, and the defense of their prerogatives within that territory. All of these behaviors drive movements that provide opportunities for hunters.

Off-season behaviors include seasonally driven movement to yarding areas, often in sheltered areas called "yards" during deep snows. These areas may see high densities of deer, at a time of low food. Deer will spread diseases more readily, and be more susceptible to predation while in yards.

Does will tend to produce two fawns, maybe one in their earliest year, and occasionally will start to produce triplets in their later years. Given a balanced herd with nearly equal doe-to-buck ratios, this implies that the population nearly doubles every spring. If the population is stable, then from spring to spring, the population will not have changed. That implies that the number which dies must equal the number born. It is the nature of deer, and a part of their success, that biology tolerates very high mortality and high fecundity for this species to do well. For more information, see DEC's deer article.

Two diseases affecting deer that are making headlines are CWD, and epizootic hemorrhagic disease. Information can be found at the listed links.

Bear reproduction is essentially a two-year cycle. Generally, black bears will come into season in early summer. Delayed implantation defers development of the embryo until late fall. During the winter dormancy period, very small cubs will be born. These cubs will stay with their mother for two years. During that time, she will not breed. Some suggestions are that the sow's defensiveness of her offspring comes in part due to the tendency of males to kill cubs, particularly of other boars, in order for the female to come into heat again. After leaving their home, young males will be chased from an older male's territory, or will be killed. This means young males will tend to wander well out of their home range. Such young boars have traveled down newly established greenways, down the Appalachian Trail, and down NYC watershed lands to the borders of NYC itself. For more information, see DEC's black bear article.    

A good summary of deer-human conflicts, together with published research can be found in a research review article.

One of the first impacts of deer involves impacts with automobiles. In 1995, State Farm Insurance estimated 1.5 million vehicles collide with deer, costing 150 lives and $1.1 billion in vehicle damages nationwide. There is a substantial literature on this topic, a review of which can be found at review, and more review.

Second are deer vectored diseases, such as Lyme disease and Ehrlichiosis.

Woodlands impacts are significant. Overpopulations, still within what would be considered "carrying capacity," can result in the destruction of the forest under story. The NYC DEP, which manages their watershed, has noted that the destruction of under-story has drastically reduced the retention of topsoil, and reduced the ability of the land to filter groundwater that feeds into the watershed. Further, such degradation has weakened watershed lands' abilities to withstand severe storms, such as the tornadoes that passed through Westchester in recent years. The NYC DEP has initiated intensive efforts, working with the QDM Association to manage their deer population on their watershed properties, opening those lands to hunters. Audubon groups in the Southern Hudson Valley have found their preservationist policy resulted in the proliferation of deer, and the destruction of under story in recently acquired lands. This adversely affected the ability of that land to support birds and other small mammals. Their forestry report recommended that the land be hunted to manage their deer population. They have connected with a local hunting club to help them with their land management problem. [Photo courtesy of John Corrao of QDM Association]

Agricultural impacts in general can be significant, with impacts cited (in "more review" link above, an article dated to Feb 2005) to be $120 million.

Bears present problems for agricultural interests. Their range has been expanding significantly, resulting in increased areas where seasons are open, and expanded hunting seasons in some of those regions. Further, hearings being scheduled to identify problems with the growing range. An example of an area where this is of particular concern involves orchards. Besides direct depredation on orchard plants themselves, orchards depend on bees, either keeping their own, or renting them from a beekeeper. Orchard growers are usually required to cover damages from bear attacks on the hives that beekeepers rent to those orchards. Beekeepers have been faced with significant problems lately, including invasive mites that kill bees, and "Colony Collapse Disorder," which has been killing large numbers of hives across the country. The increasing range of bears and the damage they can cause to bee hives is much more significant in this already stressed environment, resulting in injury not only to beekeepers, but to orchards and other agricultural interests that rely on bees for their product.