Patterns in detection rates of Swiss amphibians: Just how well can we believe our eyes… and what does this mean for amphibian species monitoring?
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Summary
Most of our knowledge of species distributions comes from people observing and reporting the species that they see. Yet everyone knows how easy it can be to miss things that are right in front of their nose, and species monitoring is no different. Observers miss seeing species when they are there (false-negative errors), and challenging species identifications mean that observers may mistakenly report seeing a species which isn’t actually present (false-positive errors). Making multiple visits to the same location can help to minimise the chance of a species going unseen, yet it’s important to understand how frequent these situations are so that this can be accounted for. Not only does this ensure that conservation decisions are based on the most reliable information possible, but it also helps to identify when changes might be needed in the way that people carry out their surveys.
Amphibians are well reported within Switzerland, which has many survey schemes which make use of networks of professional and volunteer observers to obtain information on amphibian species throughout the country. Occupancy models can be used to analyse these datasets to obtain accurate information on species distributions, while measuring and accounting for the different types of observer errors which are typical in these datasets. In this talk, I will present results from analyses of both nation-wide species monitoring, carried out by professional herpetologists, and cantonal-level species monitoring, carried out by volunteers. I will discuss differences in the false-positive and false-negative error rates between species and observers, and what this means both for how accurately species distributions are being estimated, and how well observers are capturing this information in their surveys.