Evaluation of line-transect sampling to estimate nocturnal densities of macropods in open and closed habitats

Abstract

Walked line transects were evaluated for estimating nocturnal densities of red-necked wallaby (Macropus rufogriseus) and the red-bellied pademelon (Thylogale billardierii) in a range of open and closed habitats. The use of cleared transect lines in densely vegetated habitats reduced noise produced by travelling, while permanent grid markers facilitated collection of perpendicular distance data at night. Results from sighting histograms indicated that animals did not display evasive movement in response to the observer before detection. The probabilities of detecting the macropod species varied significantly between habitats. Significant differences in probabilities of detection were also recorded within species between habitats. Consequently, line-transect sampling is recommended over strip-transect sampling for estimating species abundance when more than one species and/or habitat are of interest. Recommendations are made, however, for forest managers wanting to monitor macropod populations on newly established plantations, when line-transect sampling is not feasible and strip-transect sampling is the only alternative.