Managers talk about animal density. Density is an expression of numbers per unit area. Numbers of animals are difficult to estimate and usually are expressed as some number "between X and Y." There is imagined some invisible fluid fence that determines the boundary of the area for the wild, mobile animals. Estimating the area is difficult.
The number of acres in an area being sampled is needed. The total area is critical. It is usually best to divide the area into relevant units, (e.g., summer and winter range), and sample each separately. If the area cannot be estimated very precisely, efforts to make precise estimates of the other components of the density-estimation method may be a bit irrational. New technology can help (e.g., GPS, GIS) but managers and those who depend upon them have to be realistic about their limitations and express them clearly for greater cost effectiveness and accountability.