Graduation Date

Fall 2022

Document Type



Master of Science degree with a major in Natural Resources, option Wildlife

Committee Chair Name

Dr. Daniel Barton

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Barbara Clucas

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Erik Jules

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Robert Grasso

Fourth Committee Member Affiliation

Community Member or Outside Professional

Subject Categories



The Yosemite toad (Anaxyrus canorus) is an anuran species endemic to the Sierra Nevada in California that, like many amphibians globally, has suffered population declines. The documented decline in A. canorus populations across their historic range highlights the need for an effective management strategy to protect the species from future extirpation. For this study, I estimated survival rates of A. canorus using a Cormack-Jolly-Seber model populated with data from a demographic study. I then used a female-only post-birth pulse stochastic Lefkovitch matrix model using vital rates I estimated and from the literature to simulate the effect of different management scenarios and to optimize a supplementation or reintroduction management plan. Without any management action, small populations of A. canorus populations have ≥50% risk of quasi-extinction over the next 13 years. The implementation of effective management strategies is critical to prevent further extinction of existing small populations. My results suggest that the effectiveness of a supplementation or a reintroduction management plan is dependent on the initial population size of the receiving population, life stage at release and number of individuals released into a wild population. I found that supplementing small toad populations with female adults is the most effective supplementation strategy to increase the stochastic growth rate and minimize the risk of quasi-extinction. This thesis suggests that modeling A. canorus population dynamics and trends of extant populations can help inform conservation strategies.

Citation Style