A frog serenade
During the summer months, frogs' harmonious ribbits are music to the ears of Villebois resident Debbi Burright.
But recently, Burright was surprised to hear the amphibians in the dead of winter. And, this time, the frogs' songs weren't exactly soothing.
In fact, she compared the blaring from the Coffee Lake wetlands to the brash classic rock group AC/DC.
"I absolutely lo}ve hearing the frogs at night. They sound fabulous," she said. "That night, I was waiting for the concert to be over."
While the Pacific chorus frogs normally begin their mating calls in late February, Wilsonville residents began hearing the frogs' harmonize at varying pitches in the middle of January this year.
January was the second warmest January on record as measured at the Portland International Airport and, according to Center for Research in Environmental Sciences and Technologies (CREST) Director Bob Carlson, the abnormally high temperatures likely caused the frogs to sing earlier this year.
"They're definitely temperature-dependent so the warmer the water is the faster the eggs are going to hatch and the tadpoles are going to develop," Carlson said.
And the callings vary from year to year.
In 2011, Metro parks and nature program found egg masses in Graham Oaks Nature Park in the middle of January, meaning the frogs likely began calling in the first week of January. However, in 2009 Metro didn't find the egg masses until the end of March. Metro has yet to detect the egg masses this year, although the snow in late February could have muddled the detection process.
"If you have snow and then snow melts, it may be harder to see the eggs," said Katy Weil of Metro.
The Pacific chorus frogs, also called Pacific tree frogs, have a dark strip around their eyes, change color from green to brown depending on the environment and are the most common frog in Oregon and the state frog in Washington. They project high piercing "ribbit" calls during mating season and lower pitched "croaking" sounds in other months throughout the year. The Oregon Department of Fish and Wildlife website says Pacific chorus frogs are often heard in movie soundtracks.
"You go out behind the gym at Boones Ferry Primary in February, March and April and it's just deafening," Carlson said.
Pacific chorus frogs typically move from the uplands to the wetlands in January and stay there until July.
"Wetland habitat is something critically important to their life stages. Most frogs are going to need to be near water and plants that are associated with it," Wilsonville Natural Resources Program Manager Kerry Rappold said.
The most common species type in the Coffee Lake wetlands is the non-native bullfrog, he added, while the Pacific chorus frogs and the northern red-legged frogs are two native species in the area.
The northern red-legged frogs sing underwater and with a muffled tone and so are unlikely to be heard. They are also declining in numbers due to invasive bullfrogs, according to the Oregon Department of Fish and Wildlife.
Bullfrogs are native to Eastern North America and were introduced into Oregon in the early 1900s as a culinary delicacy. Male bullfrogs' metamorphosis from tadpoles to frogs can take up to two years.
"Like many invasive species they're opportunistic and it's an ideal habitat for them and they compete against these other frogs. They're pretty aggressive," Rappold said of the bullfrogs.
Shawn O'Neil, a Wilsonville resident of 10 years who has a koi pond, is accustomed to a particular rhythm. He begins hearing the Pacific chorus frogs in early March, hears particularly boisterous sounds in early June and then the frogs go quiet during the middle of the summer. In 2018, he heard the frogs in the second week of January.
"This year was totally bizarre," he said.
O'Neil heard the Pacific chorus frogs continue to sing, though less loudly, once the weather turned from pleasant to frigid in late February. Carlson said because the chorus frogs are cold-blooded they can acclimate to the colder climate and continue to sing despite the cold.
"When the temperature goes down they move around less so they are probably croaking less but they probably could still croak. They just wouldn't be as active," Carlson said.
Not everyone appreciates the frogs' tune.
O'Neil said one of his neighbors had to implement an air conditioning system because the singing dissuaded them from keeping their windows open. He doesn't mind the frogs though.
"If I had to choose between loud traffic noises and frogs, I'd choose frogs any day," O'Neil said.
Rappold has heard complaints about native frogs' loud singing but believes Wilsonville citizens should relish the sound.
"I've had people say things like that they can be very loud and intrusive but it's such a relatively short period of time where someone is dealing with that, especially when we're talking about our native frogs," he said. "We should support the native frogs and native sounds and recognize they're an important aspect to our community."
Burright moved into her home in Villebois last August and heard a mellower chorus then than she did in early February — though she likely heard Pacific chorus frogs in February and bullfrogs in August.
But after the loud first night in which she could hear the frogs' pitch over the television, the frogs sang more pleasantly thereafter.
"It reminds you of summer so that was kind of nice," she said.