Nearly 200 Northern leopard frog tadpoles, an endangered species, were relocated from Northwest Trek Wildlife Park in Eatonville to their new home at the Columbia National Wildlife Refuge in Royal City, Washington, in late May.
The tadpoles will continue to grow in “secured rearing pens” until they’ve matured enough to join an additional 200 mature Northern leopard frogs in the wild this summer, according to a press release from Northwest Trek Wildlife Park. This transfer will occur once the tadpoles have grown into adult frogs. The second batch of frogs will be released alongside the first group released in 2024.
“Northwest Trek Wildlife Park is proud to work with our public and private partners on the Northern leopard frog project to restore the wild population,” curator Marc Heinzman said in a press release. “It’s incredible to watch them grow from egg masses to frogs and see them hop back into the wild.”
This is the fourth year that Northwest Trek has received Northern leopard frog egg masses in the spring. These masses were collected by Washington Department of Fish and Wildlife (WDFW) biologists and came from the only remaining wild population of the species at the Potholes Reservoir.
The egg masses are raised by keepers at Northwest Trek Wildlife Park in a controlled environment where they are protected from predators, experience monitored water temperatures and are fed. The frogs are released by keepers and WDFW staff each summer with the goal of establishing a new population of the species at the Columbia National Wildlife Refuge.
“The tadpoles will continue to be protected from predators in the rearing pens, but they will be in their natural habitat,” Heinzman said in the press release. “Instead of humans feeding them, they will forage for mosquitoes from the environment around them.”
According to Northwest Trek Wildlife Park, the species was once abundant throughout North America but has rapidly begun to deteriorate from native ranges in Washington, Oregon and western Canada, leading to being listed as an endangered species in Washington since 1999.
Lindsay Nason, Northern leopard frog biologist with WDFW, told the Nisqually Valley News in August 2023 that the population of the species isn’t “doing so great” due to habitat loss and invasive species.
The NVN previously reported on Northwest Trek Wildlife Park’s raising of 300 frogs last summer.
“The Northern leopard frog is a Washington state-endangered species of pretty high concern,” Nason said. “We only have one semi-stable population of the species left in the whole state, and even though there’s a pretty widespread range in Canada and through the West, all of these states are seeing declines. There’s a lot of things going on that keep them decreasing and not recovering. Our project with the Washington department of Fish and Wildlife is we’re trying to establish translocation sites because if something devastating happens at these sites they’re already at, that’s it. It’s also not great for a population to only be in one place anyways.”
Each spring at Northwest Trek Wildlife Park, the tadpoles are weighed, measured and tagged with a “frog-friendly” elastomer dye to help track the species after they’re released into the wilderness.
In 2024, two colors of dye were used for the tracking of the Northern leopard frog species raised at Northwest Trek Wildlife Park. The first color, blue, was used for tadpoles now living at the Columbia Wildlife Refuge in rearing pens, while orange dye is for the amphibians to be released as fully grown frogs.
