Methods of Measuring Absolute Density Total counts - count all the organisms present in a population Transect or quadrat sampling - counts along a known distance or in a known unit area (small). Represents a subsample of the population. Mark-recapture methods - capture individuals, mark them in some way, resample and examine the proportion of marked to unmarked individuals.

Methods of Sampling Relative Density  Trap - any device that captures an organism  Fecal pellets - counts of pellets in an area (must be able to recognize species)  Vocalization frequencies - birds or frogs. DNR uses this to estimate ruffed grouse densities  Pelt records - recorded at trading stations and DNR offices for mammals of commercial value  Catch per unit effort - commonly applied in fisheries. How many fish are caught for some sample time.

Methods of Sampling Relative Density  Percentage ground cover - for plants or sessile animals.  Feeding capacity/damage - amount of bait taken or vegetation destroyed based back on known feeding rates  Roadside counts - number of organisms (typically birds) observed while driving some standard distance. Used for estimating pheasant and birds of prey (red- tailed hawks).

Calculations for a Life Table x = age interval (days, months, years) n x = the number of survivors at age interval x d x = number of organisms dying from the beginning of x to the beginning of age x + 1 l x = proportion of organisms surviving to beginning of age interval x q x = rate of mortality between the beginning of age interval x and the beginning of age x + 1

Calculations for a Life Table L x = average number alive from age interval x to x + 1 T x = “units of individuals times time units” e x = mean life expectancy at the start of age x