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Castle ST, Allan N, Clifford D, Aylward CM, Ramsey J, Fascetti AJ, Pesapane R, Roy A, Statham M, Sacks B, Foley J. Diet composition analysis provides new management insights for a highly specialized endangered small mammal. PLoS One 2020; 15:e0240136. [PMID: 33007017 PMCID: PMC7531790 DOI: 10.1371/journal.pone.0240136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/20/2020] [Indexed: 01/04/2023] Open
Abstract
The critically endangered Amargosa vole (Microtus californicus scirpensis) is found only in rare marsh habitat near Tecopa, California in a plant community dominated by three-square bulrush (Schoenoplectus americanus). Since the earliest research on the Amargosa vole, the existing paradigm has been that these voles are obligatorily dependent on bulrush as their only food source and for the three-dimensional canopy and litter structure it provides for predator avoidance. However, no prior research has confirmed the diet of the Amargosa vole. In this study we characterized the Amargosa vole' nutritional needs, analyzed the quality of bulrush by forage analysis, and performed microhistological and metabarcoding analyses of vole feces to determine what foods were consumed in the wild. All bulrush plant tissues analyzed were low in fat (from 0.9% of dry matter in roots to 3.6% in seeds), high in neutral detergent fiber (from 5.9% in rhizomes to 33.6% in seeds), and low in protein (7.3-8.4%). These findings support the conclusion that bulrush alone is unlikely to support vole survival and reproduction. Fecal microhistology and DNA metabarcoding revealed relatively diverse diets including plants in 14 families, with rushes (Juncaceae), bulrushes (Cyperaceae), and grasses (Poaceae) being the most common diet items. On microhistology, all analyzed samples contained bulrush, sedges (Carex sp.), rushes (Juncus sp.), and beaked spikerush (Eleocharis rostrellata) even from marshes where non-bulrush plants were uncommon. There was evidence of insects at <1% in two marshes but none in the remaining marshes. Metabarcoding detected ten genera of plants. When considering non-Schoenoplectus targets, for which metabarcoding had poor sensitivity, saltgrass (Distichlis spicata) was the most commonly detected species, with prominent contributions from seaside arrowgrass (Triglochin concinna) and yerba mansa (Anemopsis californica) as well. Diversity of vole diets generally increased with increasing site plant diversity, but differences were not statistically significant. Confirming details about dietary behaviors is critical for informing appropriate conservation planning including habitat management and reintroduction of voles into new sites.
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Affiliation(s)
- Stephanie T. Castle
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, United States of America
- Wildlife Investigations Lab, California Department of Fish and Wildlife, Rancho Cordova, CA, United States of America
| | - Nora Allan
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, United States of America
| | - Deana Clifford
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, United States of America
- Wildlife Investigations Lab, California Department of Fish and Wildlife, Rancho Cordova, CA, United States of America
| | - Cody M. Aylward
- Department of Fish, Wildlife and Conservation Biology, University of California, Davis, CA, United States of America
- Mammalian Ecology and Conservation Unit, Veterinary Genetics Laboratory, University of California, Davis, CA, United States of America
| | - Jon Ramsey
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, United States of America
| | - Andrea J. Fascetti
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, United States of America
| | - Risa Pesapane
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, United States of America
| | - Austin Roy
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, United States of America
| | - Mark Statham
- Mammalian Ecology and Conservation Unit, Veterinary Genetics Laboratory, University of California, Davis, CA, United States of America
| | - Benjamin Sacks
- Mammalian Ecology and Conservation Unit, Veterinary Genetics Laboratory, University of California, Davis, CA, United States of America
- Department of Population Health, and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, United States of America
| | - Janet Foley
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, United States of America
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