Szacowanie zagęszczenia drobnych ssaków: porównanie technik stosujących wyłów

Abstract

Kaufman D. W., Gentry J. B., Kaufman G. A., Smith M. H. & Wiener J. G., 1978: Density estimation of small mammals: comparison of techniques utilizing removal trapping. Acta theriol., 23, 7: 147—171 [With 10 Tables]. Removal trapping was conducted on 12X12 grids with assessment lines to test the relative effectiveness of the Standard Minimum, Inner Square and Assessment Line methods for small mammal density estimation. Twelve study sites were trapped in desert, chaparral and woodland habitats in California and Nevada to provide a wide array of species and densities for the comparison of estimation techniques. The procedure used was to trap each grid for 10 days followed by 4 days of trapping on the associated assessment lines. Field sites were quite variable with a range of 12—167 rodents per grid representing 2—10 species. Density estimates ranged from 3.7—51.5 animals/ha for the Standard Minimum method, 4.0—36.9 animals/ha for the Inner Square method and 0.7—114.4 animals/ha for the Assessment Line method. All methods provide restive density estimates for within method comparisons but their usefulness for estimating absolute density is limited. The Assessment Line technique probably yields the best absolute density estimates (DAL) when sufficient numbers of assessment lines are trapped; however, under most conditions a single 12X12 grid with 8 assessment lines is not sufficient. To obtain reliable Dal values, captures on assessment lines need to be combined for two or more grids from the same habitat to delineate the area of effect around a grid. Problems associated with each of the methods are discussed in detail. Savannah River Ecol. Lab., SROO, Bldg. 772-G, Aiken, South Ca