DISTRIBUTIONAL DECLINES OF TWO CRAYFISHES ENDEMIC TO THE WESTERN UNITED STATES DOCUMENTED BY COMPARING SPECIES DISTRIBUTION MODELING TO FIELD SAMPLING
Our study evaluates the current conservation status of the pilose crayfishes Pacifastacus connectens and Pacifastacus gambelii, two data-deficient species endemic to the western United States. We first developed a species distribution model for the pilose crayfishes based on their historic occurrence records, then sampled 163 sites in the summers of 2017 and 2018 anticipated to be within the native range of these crayfishes, including 53 sites where these species were observed historically. Our species distribution model predicted 52% of sites we sampled as suitable for the pilose crayfishes based on historic occurrence records, but we found them at only 20 (12%) of the 163 total sites and 13 (24%) of 53 historic locations that we sampled. At 12 (22%) of these historic locations the invasive crayfish Faxonius virilis was present, suggesting that nonnative crayfishes have displaced these native crayfishes from some of their range. Our study provides an update to the conservation status of P. connectens and P. gambelii and characterizes critical habitats for the ongoing conservation of these crayfishes, which can be used to identify and prioritize areas where management should seek to protect existing populations.
Rachel Egly (Primary Presenter/Author), Loyola University Chicago, firstname.lastname@example.org;
Eric Larson (Co-Presenter/Co-Author), University of Illinois, email@example.com;