Thesis
Anuran utilization of a semi-arid regulated river environment, the Hanford Reach of the Columbia River
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/102465
Abstract
Amphibians of large river systems are subject to highly variable hydrologic conditions, many of which likely are controlling factors regulating the formation of favorable breeding habitat. The first part of this study provides a description of anuran utilization of the Hanford Reach of the Columbia River in south-eastern Washington State. Nocturnal call surveys were conducted during 2006 and 2008 to determine breeding phenology for two native toads (Bufo woodhousii and Spea intermontana), as well as to examine site-specific utilization within the Hanford Site. Anuran calling on the Hanford Site was widely distributed throughout the upper Hanford Reach, but narrowly restricted to specific habitat types. Results from this study suggested that river discharge had a large influence on the quantity and quality of breeding sites available to anurans downstream. When adequate discharge did not occur to fill the ephemeral pools, calling neither occurred at the pool sites or adjacent fluvial locations. It is important for managers to understand the influence of discharge rates on anurans in this large river system due to the dependence of native toads on over-bank flooding. My second topic of study involved the use of radio-telemetry to examine movements and habitat use of Bufo woodhousii on the Hanford Reach of the Columbia River. Twenty-six toads were tracked in 2007 and 22 in 2008. The overwhelming majority of toads tagged in this study were males (98%), due to a scarcity of encounters with females. Habitat use included riparian and upland vegetation communities, both on daily and seasonal timeframes. There was frequent use of tumbleweed (Salsola kali) accumulations for cover, which led to an increased incidence of shed tags. Predation of toads was encountered and attributed to both avian and mammalian predators, representing a loss of 31% for both study years. A total of eight toads were tracked into aestivation, with frequent use of small mammal burrows observed during winter torpor (75%). Linear distance from breeding pool to aestivation site ranged from 103-1,573 m (mean=479 m). This study adds to a body of literature that suggests terrestrial toads commonly utilize habitats beyond 1 km from breeding sites.
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Details
- Title
- Anuran utilization of a semi-arid regulated river environment, the Hanford Reach of the Columbia River
- Creators
- Brian F. Miller
- Contributors
- Paul A. Verrell (Degree Supervisor)Dennis D. Dauble (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525154901842
- Language
- English
- Resource Type
- Thesis