A non-invasive genetic survey of otters (Lutra lutra) in an urban environment: A pilot study with citizen scientists

Acquiring reliable estimates for an elusive species' distribution and population size can be problematic. For cryptic species such as the Eurasian otter (Lutra lutra), traditional monitoring approaches rely heavily on identifying field signs that may under or overestimate population sizes. Increasingly, non-invasive genetic sampling is effectively applied to assess the abundance and population structure of otters by genotyping faeces (spraints). Here we present the results of a non-invasive survey conducted in Cork City, Ireland, which aimed to estimate otter population size, sex ratio and genetic diversity. We incorporated a citizen science approach by training members of the public in spraint collection, thus increasing our search effort and sample detection rate. From October 2011 to May 2012, 199 spraints were collected and 187 (94%) were genetically identified as otter. Of these positive otter samples, 13 spraints (7%) yielded genetic information identifying 11 individuals (5 female and 6 male) using nine microsatellite loci. The results indicate that the urban environment does not prevent otters from using the area and we consider the implications based upon contemporary knowledge on otter spatial behaviour. This study demonstrates that non-invasive survey techniques combined with a citizen science approach can effectively reveal otter population parameters and increase urban otter awareness within the community.