Translocation of a federally and provincially protected northern red-legged frog (rana aurora) population in southern British Columbia

Background/Question/Methods

The red-legged frog translocation and monitoring program was completed to mitigate potential adverse effects from the decommissioning of an infiltration pond located in Maple Ridge, British Columbia. The northern red-legged frog is listed as a species of special concern under the Species at Risk Act (Schedule 1). In British Columbia, the northern red-legged frog is a blue listed species. The landscape around the the infiltration pond was used as a gravel quarry between 1969-1984 and later as an industrial landfill. The industrial landfill utilized a pond that was that was once the quarry floor as an infiltration pond to capture surface water run-off and industrial leachate. Over the years, natural vegetation established itself within and adjacent to the pond, supporting a shallow water aquatic wetland. KFN is in the process of infilling this pond. As a result, GHD developed and completed a red-legged translocation and monitoring program. An Exclusion fence was installed around the perimeter of the pond along with pitfall and aquatic funnel traps prior to breeding migration. Dip netting and beach seining was deployed within the pond. All amphibians captured were assessed for the following biometrics: species identification, life stage, age, sex snout-vent length and weight.

Results/Conclusions

The exclusion fence and traps were in use between February and August 2021 and captured 2,127 amphibians. Between July 30 and August 6 2021, dip netting and beach seining within the infiltration pond captured an additional 2,430 amphibians. 8 egg masses were collected from the infiltration pond. Following capture and biometric measurements, all of the amphibians and egg masses were translocated to the translocation pond on a daily basis. Amphibian monitoring took place at the translocation site prior to translocation to baseline existing amphibian species and abundance. Following the initial translocation efforts, spring monitoring is proposed for 2022 to observe the presence of different life stages at the translocation pond and assess the survival success of the translocation program. The successful amphibian translocation program is only the second time such a program has been authorized in British Columbia.