|SREL Reprint #0283|
Determining Density for Small Mammal Populations Using a Grid and Assessment Lines
Michael H. Smith, Roland Blessing, John G. Chelton
A modification of the Polish Standard Minimum 16 x 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. The
number removed was equivalent to the resident population of small mammals on the
grid in only 2.8 days of trapping. 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
SREL Reprint #0283
Smith, M.H., R. Blessing, J.G. Chelton, J.B. Gentry, F.B.
Golley, and J.T. McGinnis. 1971. Determining density for small
mammal populations using a grid and assessment lines. Acta