Publication Date

Summer 2021

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Studies

Advisor

Rachel O’Malley

Keywords

distribution, habitat, newt, Taricha

Subject Areas

Wildlife management

Abstract

Anthropogenically-induced habitat loss and degradation have increased extinction rates in amphibians worldwide, yet little is known about many remaining populations. A disjunct population of red-bellied newt (Taricha rivularis), an endemic California species, was discovered 130 km south of its previously known range. Here I document the range and breeding phenology of this population and contrast its mesohabitat use with that of other sympatric newts. Surveys across two years suggest that the southern population of T. rivularis is confined to a 1 km segment of Stevens Creek, and the population follows an early-March to late-April migratory breeding pattern, similar to one documented northern population. Spatial analysis shows that T. rivularis aggregates only in Stevens Creek, likely dispersing through Twitty Creek. Breeding male T. rivularis are more associated with riffle and run mesohabitats when compared to pools, while T. granulosa and T. torosa tend to be more associated with woody debris cover types and cobble substrates. Female T. rivularis oviposition site selection is most influenced by large substrate size. The protection of large substrate and complex instream habitat in sensitive breeding reaches, as well as upland habitat along dispersal routes, should be an important consideration for land managers. Understanding the nuances of range, temporal behavior, and habitat needs for this disjunct population is critical to ensure the survival of this California Species of Special Concern.

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