Measuring Relative Density

A survey of relative density depends on collection of samples that represent some relatively constant, but unknown relationship to the true population size. Relative measures provide only an index of abundance. Relative measures include:

• Traps: Number of organisms trapped depends not only on the population density, but the activity, range of movement, and skill in placing the traps. Under most circumstances, trapping only gives you a rough idea of the population size.
• Number of fecal pellets.
• Vocalization frequency.
• Pelt records.
• Catch per unit effort (fishing).
• Number of artifacts (mud chimneys for crayfish, tree-squirrel nests, pupa cases),