Graduation Date

Spring 2024

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

Sharyn Marks

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Erik Jules

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Micaela Szykman Gunther

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Paul Bourdeau

Fourth Committee Member Affiliation

HSU Faculty or Staff


Pond-sharing amphibians, Oviposition site selection, Northern red-legged frog, Rana aurora, Northwestern salamander, Ambystoma gracile, Coexistence in Pacific Northwest

Subject Categories



Pond-breeding amphibians connect aquatic and terrestrial habitats through their biphasic life cycle, and understanding pond characteristics that support oviposition sites for multiple species is important for amphibian conservation. Two common amphibians in the Pacific Northwest, Northern red-legged frog (Rana aurora) and Northwestern salamander (Ambystoma gracile) often oviposit in the same pond; however, prior studies have focused on pond use by one species or the other, but not both together. I surveyed pond and oviposition site characteristics of 26 ponds in Humboldt County, CA, 10 of which were used only by R. aurora and 16 of which were used by both species. I found that ponds used by both species were often smaller and shallower compared to those used only by R. aurora, but most had a hydroperiod length that lasted more than a year. When using the same pond, both species deposited egg masses in the same general area, but R. aurora egg masses were significantly closer to the pond surface than those of A. gracile; both species attached their egg masses more often on submerged vegetation than emergent or floating vegetation, possibly to protect offspring from predatory insects and A. gracile larvae. I found that the percentage of canopy cover and water temperature for R. aurora egg masses was not significantly different from those of A. gracile egg masses. Although R. aurora and A. gracile select similar oviposition sites, the difference in egg mass depth from the surface allows both species to coexist in the same pond.

Citation Style

APA 7th edition


Thesis/Project Location


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