Graduation Date
Fall 2025
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Wildlife
Committee Chair Name
Barbara Clucas
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Joseph M Szewczak
Second Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Third Committee Member Name
Alison O'Dowd
Third Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Keywords
Bats, Klamath Basin, Klamath River, Dam removal, Northern California
Subject Categories
Wildlife
Abstract
River ecosystems make up a small percentage of the earth’s surface, but they support high levels of biodiversity and attract high levels of human use. Dams, for example, disrupt a river’s natural course and flow, alter water temperatures in the stream, redirect river channels, transform floodplains, and fragment river continuity, which affects ecological balance and food webs. The Klamath River in northern California, which has been dammed for the last century, experienced dramatic disruptions including a large fish die-off in 2002. With the negative impacts of the Klamath dams apparent, multiple entities negotiated to remove the dams and restore the river basin. Deconstruction of the dams began in the summer of 2023 and all four dam removals were completed by August 2024. As the largest removal effort ever completed, the dam removal project provided a unique opportunity to study dams’ influence on riverine ecosystems prior and post removal. I monitored bat species in the Klamath Basin between October of 2021 and March of 2023, ending with the beginning of dam removal (Table 2). Sites were located immediately downstream from the Iron Gate Dam to the mouth of the Klamath River in Ter-wer. My research objectives were to i) establish a baseline for bat species diversity and activity and ii) determine seasonal variation of bat species. In collaboration with the U.S. Fish and Wildlife Service (USFWS) and the Yurok Tribe, Wildlife Acoustic Mini Bat ultrasonic recorders were deployed at seven locations along the mainstem of lower and middle Klamath River. I used SonoBat call analysis software to analyze call data collected. Across all sites and monitoring nights, 14 bat species were detected along the Klamath River Basin from fall 2021 to winter 2023. Although species diversity was similar across sites overall, there was lower species richness in the winter, increased richness in the spring and fall, and peaks in richness during the summer. The number of nights of detection needed to accumulate all present species was dependent on season and site. Summer required the least amount of effort (≥10 nights), spring and fall efforts needed more effort (≥30 nights), and Winter required the most effort (≥50 nights). Detection rates varied across sites, species, and seasons. These baseline data on the bat diversity and activity will serve as an important comparison for future surveys post dam removal. The return of floodplain habitat following the removal of the Klamath dams could have a positive effect on bat activity throughout the Klamath River Basin as floodplains are of great importance to bat species as foraging habitat.
Citation Style
JWM
Recommended Citation
Matilton, Ryan Page, "Bat species diversity in the Klamath Basin prior to dam removals" (2025). Cal Poly Humboldt theses and projects. 2503.
https://digitalcommons.humboldt.edu/etd/2503