The difficulty of estimating population densities of nocturnal forest mammals from transect counts of animals

Abstract

Many nocturnal small- to medium-sized forest mammals can be surveyed only by directly sighting or hearing each individual. This is particularly so in tropical regions. Signs (footprints, dung scratch-marks, etc.) are often not identifiable to species (similar species frequently occur together); villagers' identifications are rarely clear enough for research purposes, and the provenance of specimens in markets can rarely be established to satisfactory precision. Assessments of animal status from brief surveys are becoming increasingly important for many conservation purposes. A repeatable methodology for field assessment of the status of nocturnal mammals is needed to allow comparisons, particularly between sites.