Spring is in the air (and in the water): Oregon spotted frogs are breeding
Late winter and early spring in Washington mark a crucial time for one of the state’s most imperiled amphibians — the Oregon spotted frog (Rana pretiosa). Federally listed as threatened and state-listed as endangered, these aquatic frogs begin their breeding season as temperatures rise and wetlands begin to thaw. Their survival depends on warm, shallow wetlands with low-growing vegetation — habitats that are increasingly rare in Washington due to invasive species and wetland draining for agriculture and development.
Each year, biologists from the Washington Department of Fish and Wildlife (WDFW) partner with other organizations and head into the wetlands of Skagit, Thurston, and Whatcom counties in Western Washington, as well as Klickitat and Skamania counties in southwest Washington, to count egg masses these elusive frogs lay. Surveyors cover several miles on foot — carefully wading through shin-deep water in search of grapefruit-sized clusters of frog eggs. It’s a simple, yet powerful method for understanding these frog populations.
“The information we collect is really simple,” explains Lisa Hallock, a WDFW herpetologist (a biologist focused on reptiles and amphibians). “We divide a site into transects, and then surveyors mark egg mass clusters. Each egg mass represents a breeding pair of adult frogs, so counting the total number of egg masses at a site helps us monitor how many frogs there are and how the population is doing.”
Although results from this year’s surveys are still being finalized, scientists observed an increase in egg masses at several locations in 2024. Biologists are hopeful that positive trend continues this year and beyond.
Oregon spotted frogs typically breed in shallow, still water that warms quickly in spring sunlight. Males begin calling with a soft, low-pitched “knocking” sound — more like a gentle drumbeat than the familiar croak of other frogs — hoping to attract a mate. Once paired, females lay eggs in large communal clusters, strategically placed in open, sunny areas where they’ll receive maximum warmth. This is vital for egg development.
Within three to five weeks, these gelatinous clusters give way to tiny tadpoles that feed on algae and decomposing plants. By mid-summer, the tadpoles undergo metamorphosis, transforming into juvenile frogs that begin to take their place in the delicate wetland ecosystem.
“We have years of mapping that shows us what habitat the frogs use at high water, at low water, and in between,” says Hallock. “That gives us an idea of what the important habitat is at given recovery sites.”
But even as new generations hatch each spring, the Oregon spotted frog continues to face significant challenges. Historically found across the Pacific Northwest from southwestern British Columbia to northeastern California, the species now inhabits a fraction of its former range in Washington. The primary culprits for their decline? Invasive species and habitat loss.
Invasive reed canarygrass grows tall and dense in the wetland shallows making those areas unsuitable as breeding sites, while invasive American bullfrogs prey on Oregon spotted frogs and compete for food and habitat. Non-native warmwater fish such as bass and bluegill are also threats to Oregon spotted frogs because they prey on tadpoles and small frogs. Wetland draining for agriculture and development also led to habitat loss and degraded and fragmented their breeding and overwintering habitats.
Additionally, below average precipitation and drought years are increasing in frequency, and this is a significant concern as it can make all the above factors more severe. To combat these pressures, WDFW and conservation partners are working to restore and manage wetland habitats.
In many areas, this includes controlling bullfrog populations and removing invasive plant species. Mowing, haying, or grazing reed canarygrass are important techniques we use to keep the grass short so it doesn’t shade the breeding areas. Restoration efforts also focus on replanting native vegetation that supports these frogs’ lifecycle.
Importantly, these efforts extend beyond public lands. Private landowners play a crucial role in Oregon spotted frog conservation.
“We have a lot of sites on private lands, and landowners are our conservation partners,” Hallock says. “As their land management practices change, we work with them to help keep conditions suitable for these frogs.”
In fact, some of the most successful recovery areas are on private properties where landowners have committed to protecting and restoring habitat. By managing water levels, limiting livestock access to frog breeding areas during the breeding season, and maintaining native plant communities, landowners can make a measurable impact.
Protecting the Oregon spotted frog doesn’t just help one species — it strengthens the health of entire wetland ecosystems which support a diversity of wildlife including birds, rare native fish such as the state sensitive Olympic Mudminnow, and other amphibians. These wetlands also filter water, store carbon, and reduce flood risks, providing benefits to both nature and people.
Whether you’re a landowner, a community scientist, or a nature lover, you can be part of the solution to benefit these rare frogs and Washington’s wetland ecosystems. By working together to protect these precious wetlands, we ensure that the Oregon spotted frog’s quiet knocking call can continue as the wetland waters warm to usher in each spring.
Learn more about the Oregon spotted frog and how you can help by watching this video and visiting our webpage: wdfw.wa.gov/species-habitats/species/rana-pretiosa#conservation
If you are a landowner with property in Klickitat, Skagit, Thurston, or Whatcom County and want to help the Oregon spotted frog, WDFW can provide technical assistance to survey for the frogs and protect, manage, or improve the species’ habitat on your land. Cooperative conservation programs provide incentives to private landowners who help with the recovery of imperiled species. For more information, please contact WDFW at 360–902–2515 or email wildthing@dfw.wa.gov.
