A population is define as a group of one species of organisms occupying the same general area, using the same resources, and acted upon by the same environmental factors. Populations cannot grow indefinitely, many populations will become stable over a period of time while others will show sharp increases followed by similar decreases. Population characteristics that afford study are its density and the spacing of its individuals.
Population density is the number of individuals per unit area or volume.
Population dispersion is the pattern of spacing among the individuals within the parameters of the geographical boundaries of the population. Due to the impracticality of capturing or counting each individual in a given area, ecologists use a variety of methods to determine the density of various populations of organisms. Counting the number of nests or burrows in a given area, examining the number of tracks, examination of solid waste products left behind, and an actual capture method called mark - recapture. In the mark-recapture method, animals are trapped within their boundaries, marked with a long lasting sign, and released. At a later time some of the animals will be recaptured along with other that are not marked.