Wildlife CDE Vocab

Carrying Capacity

Carrying capacity is the number of animals an area of land can support over a substantial length of time which includes periods of stress (i.e. drought) without damage to the habitator population. Limitations might be food, water, cover, terrain, or even soil. A wildlife manager may identify habitat limitation(s), and then, based on goals and objectives manipulate the habitat to increase, decrease, or maintain the present population.

Diversity

Diversity, in this context, is a habitat term used to describe the variety of plant species and plant structure. For example, a 1,000-acre tract with 300 acres in mature hardwoods, 200 acres of native pasture, 200 acres of a number of young brush species and 300 acres of a number of older brush species would have reasonably high diversity.

Interspersion

Interspersion refers to the arrangement of various habitat types within an area. In the example used in defining "diversity," if the four vegetative types are each contiguous 200- or 300-acre blocks, then the interspersion is low. However, if the four different vegetative types are broken into 10 to 20-acre blocks of various sizes, the interspersion is very high. High interspersion is not always desirable. The red-tailed hawk, for example, requires approximately 212 acres of contiguous bottomland hardwoods per nesting pair.

Population

Population is the number of organisms found on an area at any given time. Thus, population varies from one month to the next, depending on births, deaths, immigration, and emigration

Saturation Point

Wildlife managers can increase carrying capacity by increasing the basic habitat requirements of food, cover, water, and space. This allows more animals to survive the crunchperiod. However, due to social factors (i.e., an animal's tolerance to crowding) there is usually a "social" limit to a species' carrying capacity regardless of food, cover, and water.

Surplus Population

For most wildlife species, there is a "crunch period" where food, cover, or water is the most limiting and the standing crop is at its lowest. During these periods, typically in late winter throughout Texas, mortality must remove the surplus population. Therefore, surplus population refers to the animal numbers above carrying capacity. Unfortunately, the population of grazing species' such as deer, rabbit, elk, and bison, can reach surplusnumbers during a period of limited food. When this occurs, habitat damage due to overgrazing is usually the result.Wildlife biologists manage populations through hunting to remove surplus 15 animals prior to the crunch period. This management activity protects the habitat andensures herd health.

Turnover

Turnover of a population represents the replacement of old individuals by new ones. It is expressed as the rate or the time that it takes for all individuals in a population to be replaced. A population may be relatively constant in total numbers but may have a very high mortality rate. Turnover rates of 70 percent or higher are not uncommon for small birds andmammals.

In summary, it is essential to understand how populations function in order to achieve a management goal. It is easiest to increase wildlife populations by increasing carrying capacity. To increase carrying capacity, the limiting factor must be determined, then lifted. Populations that are at carrying capacity cannot be increased by protection.

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