Question

A biologist marked 200 mice, by putting leg bands on them, out of a forest containing an unknown number of mice. The marked mice were then returned to the forest for 6 months to mix thoroughly. 250 mice were later trapped and 40 of them were found to have leg bands. What is the estimated population size of the mice in this forest

Answer 1

Answer: The estimated population is 1250 mice

Explanation: The method use was marked and recapture, in which individuals are marked in the first capture and after some time biologist trap a new group of individuals that can be or not marked

Whit this data is possible to estimate the size of a population applying the Peterson method but is important to make some considerations such as:

1. All indivuals have the same probability to be capture

2, The population remain constant in terms of birth and death rate.

Taking this into account, the formula that allows to determine the size of the population is:

N=CM / R  

where N is the size of the population, C is number of indivuals trapped in recapture, M is number of individuals marked in the first capture and R is the number of marked animals trapped in recapture

In this case:

N = 250 * 200 / 40 = 1250