Locating Amphibian Egg Masses
What species of amphibians are thriving in the Pacific Northwest? One way to find out is to locate and identify their egg masses, and March is a perfect month to monitor for amphibian egg masses in the ponds at Northwest Trek.
Just north of the wildlife park is a 4-acre wetland mitigation site where this search frequently takes place. “This is an ideal place for monitoring egg masses,“ says Northwest Trek’s Conservation Program Coordinator Rachael. “Since the wetland’s restoration, we’ve identified eggs from seven of the eight monitored species of stillwater-breeding amphibians.”
“The biggest diversity of amphibian species occurs in these ponds in the first few weeks of March,” Rachael explains. So, when March rolled around, it was time to put on our waders and take to the ponds of this mitigation site in search of egg masses.
Joining us during this egg monitoring expedition is longtime volunteer Peggy, who is no stranger to these waters. Clipboard in hand, Peggy is tasked with the important work of writing down the precise life stage, quantity and habitat information of the egg masses present. Along with a photograph of each egg mass, this data is then shared with the Washington Department of Fish and Wildlife to learn more about amphibian populations and support conservation efforts. Peggy tries to get out to the ponds as much as possible during egg season. “Sometimes I even go out as much as two times a week” she says.
Differentiating Egg Masses
There are four egg masses that you will commonly find around Northwest Trek in mid-March, that of the northwestern salamander, Pacific treefrog, northern red-legged frog and long-toed salamander.
As we search around the first pond at the mitigation site, Rachael gives us a clue: “As you scan the waters, look for an unusual shape, something transparent or translucent, and often attached to vegetation.”
After a minute or so in the water we find our first egg mass! That of the northwestern salamander, submerged a few inches underwater and attached to a twig. It looks like an underwater translucent orange with seeds. After spotting one we quickly see four more northwester salamander egg masses within feet of the first.
Next, just barely below the surface of the water we locate an egg mass of the Pacific treefrog. “Notice that the eggs are a lot smaller than the ones of the northwest salamander,” says Rachael. “Also, the eggs are tightly packed together, as each egg only has a thin layer of jelly.” Rachael explains that the thin jelly layer is another way to distinguish these egg masses from long-toed salamander egg masses that have a wide jelly layer surrounding each egg, making the eggs appear widely spaced within the cluster.
Rachael laughs, “Pacific treefrog egg masses always make me think of a miniature galaxy.”
Third to be located is a long-toad salamander egg mass. Right away we notice each egg already developing into the shape of a salamander larvae and having more of a brown color. Rachael explains, “The long-toad salamander eggs have small packets and sometimes will only have a single egg per packet. If you look closely, you can even see the gills starting to form.”
And finally — in the last pond we wade into for the day — we find the Northern red-legged frog egg mass. It has more of a grape cluster appearance with soft jelly, which distinguishes it from the firm egg mass of the northwestern salamander. Rachael tells us that the egg masses of the northern red-legged frog often will drift off from the vegetation where they were originally laid and float to the middle of a pond before hatching.
It’s hard to stop searching for the day as it’s quite the fun activity, but Rachael lets us know there are many reasons to return. In a few weeks many of the egg masses we saw today should hatch and the tadpoles will leave their masses. Also, she expects western toad eggs to be visible starting in April.
Monitoring amphibian egg masses – and training others to do it – is something Northwest Trek has been doing since 2011. Amphibian egg mass monitoring could be a matter of life or death for some species. The Oregon spotted frog is endangered in Washington, and threatened U.S.-wide. It’s the only monitored species so far not spotted at Northwest Trek.
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