Censusing Mouse Populations by Means of Tracking

A new approach based on mark—and—sample tracking is presented that may substantially reduce errors in censusing small mammals. A test is included to check the underlying assumption of equal tracking from marked and unmarked mice. A procedure for applying the tracking approach to estimating births and deaths between samples is also presented. The tracking approach was demonstrated on a population of Peromyscus maniculatus. The number of tracks left nightly by males was significantly greater than by females. However, the tracking rate was about the same each night for all individuals of the same sex, even though tracking fluctuated from night to night. The test revealed no strong difference in the tracking rates of marked and unmarked mice. It is concluded that population estimates based on tracking can be highly precise and are far superior to estimates based on trapping alone.