Terry Walshe, Kirsten Parris, Mick McCarthy and I have a new paper out in the journal Diversity and Distributions that tackles the issue of how to determine the probability that a species occupies a given location after a number of failed attempts to find it there (check it out). It’s not quite as simple as you would think, even if you have a good handle on the ‘detectability’ literature. In the paper, we describe an approach to determining how many non-detections would be necessary to be X% sure that a species is not present at a given location. This method is particularly useful for designing impact assessment surveys in which the probability of failing to detect an endangered species that occupies the site needs to be set to some comfortably low level (e.g. 5% chance).
Terry Walshe wrote a nice piece about the paper in our decisions Hub’s magazine Decision Point (check it out).