Resource Selection of an Endangered Mouse Perohnathus Longimembris Pacificus: Using Plant Cover Surveys and Scat Analysis

Abstract

Resource selection of the endangered Pacific Pocket Mouse (Perognathus longimembris pacificus; PPM) is poorly understood and past limitations in study methods have left a gap in an important part of the life history of the species. Understanding what types of resources they are consuming and when are important for current and future species management decisions regarding habitat enhancement and reintroduction sites. Therefore, I used data obtained by metabarcoding of PPM scat and plant phenology survey data to estimate food availability, to assess diet composition and analyze diet selectivity (diet composition – food availability) at the plant functional group level for the rodent community throughout two PPM populations. The study was performed at two extant populations on MCB Camp Pendleton in 2016 and 2017. Plant phenology surveys show trends in resource availability that matched what was expected in a coastal sage scrub habitat type. Diets for PPM and competitor rodent mimicked each other at both populations across multiple seasons and years. Also, forb use was high by PPM and competitor rodent species at both populations across seasons and years regardless of the percent cover of other functional groups. Understanding PPM resource use from this study will inform land managers how to better manage PPM habitat and make decisions to enhance currently occupied and future reintroduction sites. Future work to understand the specific plant species being used by PPM and their competitors will build on the work done in this project.