An improved method of microhabitat assessment relevant to predation risk

Animals may select the microhabitats they use in response to a real or perceived risk of attack by visually hunting predators. However, to demonstrate this requires measuring visual cover at the microhabitat level, which can be labor-intensive and may require specialized equipment. Simpler methods lack repeatability, particularly when multiple observers are involved. We devised, and describe here, the quadrant cover method (QCM), which provides rapid, objective assessment of the degree of concealment that microhabitats provide from visual predators. Our method gives results that correlate strongly with those obtained using a conventional sight board, but requires less than 25% of the time. The method is highly repeatable, with negligible observer bias. The QCM is ideal in microhabitat studies in which the variable of interest is visual exposure to other animals such as predators.