Ecologists use techniques too figure out the population density of an area.

The population density is the number of individuals or a particular species per unit area or volume.

The way ecologists find this is using a formula:


Population Density = Individuals\Unit area


Ecologists use different sampling techniques to estimate the population density.


  • Quadrats- Ecologists mark off an area and see how much of one species is in the area,

They repeat the cycle & average it out to estimate the population density.

  • Indirect Counting- Ecologist count nests, burrows, or tracks rather than the organisms themselvels.

  • Mark-Recapture- Ecologists trap animals in the study area and mark them, then release the marked animal.

After a period of time, the researcher again, captures animals & counts them number or marked & unmarked animals in the second sample.

They use the following formula to estimate population size:


Total Population = # of animals in first capture * # of animals in second capture

# of marked animals recaptured