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Habitat use is one of the first factors considered when determining limitations on species abundance and distribution. For species being considered for some level of protection there are existing data describing habitats in which they have been found as well as abundance estimates.
When projects are proposed in areas with potential habitats for the species it is common to survey these habitats for the species’ presence. The survey methods seek data to answer this question: What is the probability of the species occupying a site if it is not observed during a visit?
This question cannot be answered using frequentist (null hypothesis significance testing) statistical models because these measure frequencies of long-term averages rather than predicting the probability of a single observation.
Because data exist for the presence of the species in the habitat type even when they are not observed, these data are used to calculate the probability of the species being present but not observed. This prior information is applied using Bayes’ Rule of conditional probability: the probability of the species being present but unobserved given that it has been seen in these habitats in this, or other, locations. The proportion of prior observations of the species in this habitat is the prior probability of its presence in the one being surveyed.
This work was originally published on the Applied Ecosystem Services, LLC web site at https://www.appl-ecosys.com/blog/factors-limiting-species-populations-2/
It is offered under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International license. In short, you may copy and redistribute the material in any medium or format as long as you credit Dr. Richard Shepard as the author. You may not use the material for commercial purposes, and you may not distribute modified versions.
