Assessing Habitat-Use Patterns and Survey Methodologies of the Endangered Snail, Pecos Assiminea, at Bitter Lake National Wildlife Refuge

Pecos Assiminea is an endangered, semi-aquatic snail endemic to two spring systems located in eastern New Mexico and west Texas. Basic biological information needed for effective monitoring and conservation is currently lacking for this species. Our objectives were to compare the effectiveness of surveys using two gear types, quadrats (n = 366) and weathered wooden tiles left on the substrate (n = 549), for estimating Pecos Assiminea distribution and relative abundance, and determine Pecos assiminea habitat use at two sites at Bitter Lake National Wildlife Refuge (BLNWR) in New Mexico.  Pecos Assiminea presence in the quadrat surveys was associated with soil temperature, distance to the water’s edge, and percent cover of common reed, kochia, saltgrass, and bulrush. Detection of snails was higher in the surveys of wooden tiles than those using quadrats. However, there was no clear relationship between population densities estimated by the quadrats and the probability of individuals being found on the wooden tiles. Wooden tiles seem to be a cost effective method of determining Pecos Assiminea presence, but they may not be capable of generating reliable estimates of abundance or habitat use. Our data will inform planned restoration and conservation actions for Pecos Assiminea at BLNWR.