Amphibian Egg Hunt
By Erik Robinson, The Columbian, Vancouver, Wash.
Mar. 9–DULUTH — You can learn a lot about an area by its frogs.
Amphibians need plenty of water, ideally in wetlands capable of supporting a wider array of wildlife. But simply preserving scattered wetlands won’t be enough to support healthy populations of native amphibians such as red-legged frogs, which spend much of their adult lives in nearby forest land.
Scattershot wetlands situated amid wall-to-wall subdivisions won’t cut it.
“Native amphibians breed in the ponds, and as adults, they need uplands,” said Peter Ritson, an environmental science instructor at Washington State University Vancouver. “By protecting wetlands, we’re protecting a buffer around them, but we’re not (systematically) protecting the substantial habitat they need as adults.”
Of course, that kind of complexity is increasingly rare in an area urbanizing as rapidly as Clark County. It’s why Ritson is counting amphibians while there are still plenty left to count.
On Saturday, Ritson, along with volunteers Nancy Mendoza of La Center and Andrea Vizcaino of Vancouver, pulled on hip-waders and slogged along the edge of one such wetland mitigation pond the county recently created near the intersection of Northeast 199th Street and 29th Avenue.
Instead of watching out for toads, salamanders or frogs, the trio scanned for gelatinous clumps of eggs nestled along the pond’s edge.
“The eggs are very easy to identify, and they don’t run away,” Ritson explained.
Ritson’s project, underwritten by an $8,000 grant from the Washington Department of Fish and Wildlife, involves more than 50 volunteers surveying amphibian egg clusters in dozens of locations around Clark County. Some of the volunteers are traipsing across their own property.
They search each site at least twice to establish a sort of herpetological baseline census.
“The only way to get this data is to have citizens do it,” Ritson said. “No biologist — city, county, state or federal — has time allocated to do this type of work.”
The volunteers are primarily looking for native amphibians, such as the northern red-legged frog, northwestern salamanders, western toads, long-toed salamanders and the relatively abundant Pacific chorus frog — commonly known as a tree frog. Distinguishing the various egg masses quickly becomes second-nature.
“Here’s one,” Mendoza called out.
The rice-size black eggs were encased in a mass of watery green goo a little bigger than a softball, anchored to a willow twig growing out of the water. Each red-legged frog mass contains up to 1,000 eggs. Predators, lack of food, poor weather and plain bad luck will eliminate almost all of them before they reach adulthood.
For the species to maintain itself, two must survive.
During the first survey of this site, on Feb. 11, volunteers found only one red-legged frog egg mass. On Saturday, they found 15, plus one northwestern salamander egg mass. They also found more than 100 tree frog masses, along with a few adult tree frogs.
The salamander mass was much spongier than the liquid-like frog masses, about the size of a baseball, with brownish eggs. A relatively small piece of forest land on one corner of the property, surrounded by a mix of newer homes and hobby farms, wasn’t quite enough to support a more-abundant population of salamanders.
“They need more extensive upland habitat,” Ritson said.
Erik Robinson writes about the environment. You can reach him at 360-735-4551 or erik.robinson@columbian.com.
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