Bend Bulletin: Spotted frog numbers rise in Upper Deschutes, biologists say
By Michael Kohn
Following decades of decline, the population of Oregon spotted frogs in the Upper Deschutes Basin is showing signs of a rebound, a signal that the region’s unhealthy wetlands are beginning to recover.
Lena Chang, a spokesperson for the U.S. Fish and Wildlife Service, described Oregon spotted frog counts as being “generally up” across their range since 2024, including counts in the Upper Deschutes Basin. Chang said in an email to The Bulletin that the upward trend is due to both human intervention and improved climatic conditions.
“In general, the frog responds positively when we have wet years following drought,” said Chang. “We are also likely seeing positive population responses from implementing recovery actions such as aquatic restoration and bullfrog removal.”
Central Oregon experienced three straight winters of above-average snowpack following a period of extreme drought that left reservoirs empty and caused a decline in groundwater levels. The recovery efforts for spotted frogs include the capture and removal of bullfrogs from areas around Sunriver. Bullfrogs are an invasive species that feed on the significantly smaller Oregon spotted frog.
The Oregon spotted frog — listed as a threatened species under the Endangered Species Act — has been heavily impacted in the Upper Deschutes Basin by dams and diversions which alter the wetland areas they inhabit. Across its historic range, the spotted frog has disappeared from around 76 to 90% of its wetlands.
Biologists say the Oregon spotted frog serves as a barometer for the ecological health of wetlands ecosystems. When a wetland can support a population of spotted frogs it is also contributing other functions as a healthy ecosystem, including flood control, water filtration and carbon storage.
In addition to more water in their ecosystem, the removal of bullfrogs appears to be having positive effects. In 2017, when bullfrog removal started in the Upper Deschutes, biologists counted just 335 spotted frog egg masses around Sunriver. By 2018, the number rose to 764 egg masses. Since 2020, egg mass counts have ranged from 434 to 561.
While spotted frog counts are likely showing positive signs, the species still faces an uphill battle for recovery.
Biologists say connectivity between populations remains a challenge. Good connectivity allows them to move between wetlands, which improves their chances for breeding, feeding, and survival. Without these links, isolated populations face inbreeding and are far more vulnerable to drought, predators, and habitat loss.
“We ranked connectivity as moderate-low because approximately 65 percent of the designated critical habitat within the sub-basin is fragmented by water management operations at Crane Prairie and Wickiup reservoirs, making connectivity between Oregon spotted frog populations limited,” according to a recently published biological report on spotted frogs.
How the spotted frog fares over the long term remains an outstanding question. Its outlook also depends on the implementation of the Deschutes Basin Habitat Conservation Plan, a 30-year commitment by irrigation districts to reduce water waste and increase the flow of the Deschutes River in winter. Keeping targets on pace for increased flows depends heavily on federal funding for piping projects.
But for the next year, at least, the federal government appears committed to Oregon spotted frog conservation. Chang said monitoring, aquatic restoration and bullfrog removal are expected to continue in 2026.
Read more at: https://bendbulletin.com/2025/12/10/spotted-frog-numbers-rise-in-upper-deschutes-biologists-say/
