Determining density for small mammal populations using a grid and assessment lines

A modification of the Polish Standard Minimum 16 × 16 grid was used to obtain density estimates. Eight assessment lines were used to evaluate the area of effect around the grid. Mammals were removed out to 98 m from the grid. Theoretical considerations for the density calculations using data from the assessment lines are given along with an example. Density as calculated by the method recommended in the Polish Standard Minimum method was 81 % higher than the comparable figure (15.99 small mammals per ha) calculated by the assessment line method. The discrepancy results from the movement of mammals onto the plot during the removal phase of the study. Future studies must evaluate the area of effect around the grid; the assessment line method is the only known way of efficiently estimating the size of the border zone.