Harborton Frog Mortality Assessment

Northwest Ecological Research Institute (NERI)
$2,500
 Additional Funding  by Oregon Zoo

Harborton Wetland is a 74-acre parcel located along Multnomah Channel within the historic Willamette River Delta and owned by Portland General Electric (PGE). Since the city was founded, most of the wetlands and riparian habitats of the Lower Willamette River Basin have been destroyed. Annually, hundreds to thousands of Northern red-legged frogs (Rana aurora, RAAU) migrate from terrestrial uplands in Portland’s Forest Park across Highway 30 to the Harborton Wetland to breed. During this migration, passing cars kill an unknown number of animals. Conservative estimates put amphibian road crossing deaths in the hundreds at this site, but the number could be substantially higher with evidence of soft frog carcasses disappearing rapidly on this busy highway. In 2014, the Harborton Frog Shuttle was established to assist the frog migration and reduce the effects of anthropogenically inflated mortality. While the shuttle is a great tool for community involvement, a more sustainable and permanent solution is called for. A wildlife undercrossing and/or creating improved wetland spaces that do not require road crossings are the primary proposed solutions. These are expensive, infrastructure-based solutions and more data is required to find the most appropriate path forward. Specifically, increased data on the rate and location of frogs being killed at road crossings will inform timing and movement patterns to find the best solution. The Northwest Ecological Research Institute (NERI) has performed amphibian surveys and restoration for decades throughout the Pacific Northwest.

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