Otter surveys monitor the elusive, rare, and largely nocturnal species and involves a suitably qualified ecologist searching for evidence of otter presence, such as: Dung (spraints) Tracks (footprints) Feeding remains Slides (into water) Holts (underground dens) Couches (above ground sites where otters rest during the day) Surveys can be undertaken at any time of year, but the best time is spring when evidence is often easier to find as water levels recede and wet mud is exposed allowing, for example, paw prints to be seen more easily.