Document Type
Thesis - Open Access
Award Date
2024
Degree Name
Master of Science (MS)
Department / School
Natural Resource Management
First Advisor
Amanda E. Cheesman
Abstract
North American river otters (Lontra canadensis) play a critical role as an apex predator in riverine ecosystems. A challenging species to survey using traditional methods, they remain understudied in non-forested regions, such as the Northern Great Plains, where habitat degradation and landscape fragmentation may reduce habitat quality and availability and disrupt landscape connectivity. This thesis aims to improve detectability and investigates the habitat use of river otters in South Dakota to better understand habitat needs of otters and improve their continued recovery and management. My first chapter provides a brief overview of river otters and their ecological roles in freshwater ecosystems. River otters rely on resources like aquatic prey and den site structures, but habitat degradation and agricultural impacts can disrupt these environments, threatening prey availability and riparian health. In my second chapter, I evaluate the use of different trail camera settings, specifically the use of timed-triggers in addition to motion-activated triggers, for detecting river otters in field surveys. I found that incorporating timed-triggers led to a 300% increase in detections compared to motion-activated triggers alone, providing a valuable tool for surveying cryptic species like otters. My third chapter uses spatial occupancy models to explore river otter detection probabilities influenced by site-specific factors (e.g., stream width, stream depth, and lure type) and habitat use across South Dakota in relation to land cover types (e.g., wetlands, forests, croplands), Normalized Difference Vegetation Index (NDVI), and beaver presence. I had two competitive models, finding negative relationships between river otter use and croplands and grasslands, and a positive relationship between NDVI and river otter use. Further, I found that the addition of food-based lures in addition to river otter scat as a lure resulted in lower detection rates. Finally, the fourth chapter concludes my overall thesis with a discussion on my findings and their relevancy for the continued recovery and management of North American river otters.
Publisher
South Dakota State University
Recommended Citation
Speiser, Jessica, "Methods for Optimizing Detection and Evaluating Habitat Use of North American River Otters in South Dakota" (2024). Electronic Theses and Dissertations. 1348.
https://openprairie.sdstate.edu/etd2/1348
Rights Statement
