Graduation Date
Fall 2025
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Karen Kiemnec-Tyburczy and Sharyn Marks
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Paul Bourdeau
Second Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Third Committee Member Name
Michael Westphal
Third Committee Member Affiliation
Community Member or Outside Professional
Keywords
Amphibian, Rough-skinned newt, Larval ecology, Northern coastal California, Plasticity
Subject Categories
Biology
Abstract
Rough-skinned newts (Taricha granulosa) occur along the Pacific coast of the U.S. from central California to southwestern Alaska at elevations from zero to 2,800 m. Across that range, the timing and duration of various life history events (i.e., hatching, metamorphosis, breeding, and oviposition) are largely unknown, although general trends have been observed in a few locales. Larval life stages are particularly important for determining amphibian population persistence, but there have been no formal studies describing the larval period of rough-skinned newts. Using minnow-trap and dip net surveys at nine lentic sites in northern Humboldt County, California (elevations 400 – 1,000 m), I observed differences within a small geographic range in timing of detection of hatchlings, timing of detection of metamorphosing larvae, length of larval period, and larval body size. I detected hatchlings at seven of the nine sites: from June-July at two sites, July-October at two sites, and on only one day at three sites. I detected metamorphosing larvae at six of the nine sites and found that metamorphosing larvae in ephemeral ponds were significantly smaller than those in permanent ponds. The larval period ranged from 4-12 months. I detected overwintering larvae at five (56%) sites. I found variation in tailfin height that was correlated with levels of estimated predation within ponds. While larval body size (SVL and TL) and body condition varied significantly with different environmental factors, I did not find an association between those environmental factors and length of larval period. This suggests that timing and duration of larval period and larval body size in rough-skinned newts are plastic and influenced by multiple environmental conditions within ponds. My sampling efforts revealed that dipnet sweeps were a much more effective way to catch larval newts than minnow traps.
Citation Style
APA
Recommended Citation
Parker, Emmery R., "Variation in the timing and duration of rough-skinned newt (Taricha granulosa) larval period in the center of their geographic range (Humboldt County, California)" (2025). Cal Poly Humboldt theses and projects. 2508.
https://digitalcommons.humboldt.edu/etd/2508