Reed College Canyon

Urban Restoration and Conservation: Reed College Canyon and the Pacific Treefrog, Pseudacris regilla

author: Alexandra Schaich Borg
advisor: Bob Kaplan
year: 2005

ABSTRACT: Two years ago, Pseudacris regilla were translocated into the Reed College Canyon from Oaks Bottom Wildlife Refuge as part of a senior thesis investigating amphibian translocation. This thesis is a follow-up to that translocation. Evaluation of the effectiveness of this translocation by determining size and status of the current P. regilla population was not possible due to the third driest winter and spring that caused P. regilla to remain underground. Previous assessment of the suitability of the canyon as a P. regilla habitat compared tadpole survival and development in the laboratory in water from the canyon vs. from Oaks Bottom. The present study questions that assessment. A critical analysis of habitat suitability in the current study reveals significant ecosystem differences that could be critical to P. regilla survival. Oaks Bottom contains more exotic, invasive vegetation than the Reed College Canyon. While both habitats have permanent water bodies, only Oaks Bottom has ephemeral pools, which provide breeding sites with less predation. The water is more acidic at Oaks Bottom but contains higher levels of nitrates in Reed Canyon. Reed Canyon also has more predators than Oaks Bottom. Questions must also be raised about other environmental factors such as traffic, noise, and dispersal. Altogether these consideration suggest that the Reed College Canyon may not currently provide a site that will support long term survival of P. regilla. A revised program for introducing the Pacific Treefrog into the canyon is proposed that identifies additional information still needed to determine habitat suitability and suggests management practices that will be required for successful translocation of P. regilla into the Reed College Canyon. Since the canyon is becoming a major resource for watershed conservation in the area, working wildlife into the restoration would set an example for urban restoration and, if successful, the lessons learned should be helpful to save the threatened Red-legged frog, Rana aurora.