A Walk in the Woods with Amphibians by Amy Yahnke, PhD
Amy Yahnke, Senior Ecologist at the Department of Ecology, has brought her incredible knowledge base about amphibians to our February Amphibian Monitoring training at Camp Long as well as to the Hazel Wolf Wetlands monitoring team! Below is an account of her experience with Amphibian Monitoring, including some fantastic in-depth info on some of the amphibians her team encountered.
After spending eight years studying amphibians for my graduate work, I still have dreams about being in the field searching for amphibians. I always wake up from those dreams missing that feeling of standing in a wetland in my chest waders and spotting a pair of ranid eyes watching me from just above the water surface. I was excited to join the Woodland Park Zoo Amphibian Monitoring Project and get a chance to be in the field searching for amphibians again. Volunteer amphibian monitoring is great fun plus it allows members of our community the opportunity to make a valuable contribution to Puget Sound environmental science.
I joined the Hazel Wolf monitoring team because the wetland is located near where I did my Master’s work studying amphibians in stormwater ponds. I was unfamiliar with the site and curious about its amphibian population. Hazel Wolf is a large, beaver-impounded wetland in Sammamish with a trail that loops around it through upland forest and, in some places, through the wetland. Diana and Valerie Koch have been the primary survey team for this wetland for several years. Their approach is primarily a “light touch” survey along the trail. Light touch means that we walk the trail and check in the surrounding leaf litter and look under logs, at the base of sword ferns, bushes, and trees for amphibians that might be hiding there. In this approach, anything that is over-turned or disturbed is replaced as close to its original position and level of cover as possible.
The light touch approach is a little different than the standard “walk around the edge of the wetland” approach that we normally use to look for amphibian egg masses. Using light touch at Hazel Wolf is necessary because the edge of the wetland is not accessible in many places and it can be difficult (not to mention destructive) to walk through the wetland the whole time. We also look in the water where the trail passes through the wetland, but much of the trail is through the surrounding upland forest. Because we use light touch along the trail at Hazel Wolf, we actually have the opportunity to meet some species or life stages that we might not normally see during a day-time survey around a wetland’s edge. The last two survey outings were quite fruitful in this way.
I knew that our surveys in the upland along the trail might turn up a couple of salamander species we didn’t learn about in the training because they don’t breed in the wetland, and sure enough on our survey in March, we found one of our terrestrial-breeding salamanders, Ensatina (Ensatina eschscholtzii). Ensatinas can be found hiding under a variety of covers in upland forests, including in piles of rocks or debris, under logs, or under the skirts of sword ferns. Sometimes they will hang out and let you get a picture, and other times they will quickly disappear down channels in the soil or through leaf litter. Ensatinas are generally of a pretty uniform, orange-brown color. One sure way to tell Ensatinas from the variety of other salamanders we can find hiding in similar places is that there is a pinch at the base of their fat little tails. That’s where they are able to drop their tails and make their escape if a cunning predator happens to grab hold. It’s a common defense mechanism of lizards and salamanders, and Ensatinas have that ready-made spot at the base of their tails to be able to make a clean break for it, literally.
During our survey in April we found several different types of amphibians along the upland trail that do breed in wetlands and were included in our training. We found several Northern Pacific Treefrogs (Pseudacris regilla) that almost ran the full gamut of the color variation expressed by that species. One Northern Pacific Treefrog was even trying to fool us into thinking it was a Northern Red-legged Frog, but those rounded toe-tips and that fancy eye mask gave it away. It got away before we could get a good picture.
Valerie scored big finding two species in life stages that I had not seen in the upland forest habitat before. The first was a juvenile Rough-skinned Newt (Taricha granulosa) hiding under some leaf litter. It was especially exciting to see because it’s a life stage for which we don’t have a lot of data on the newts. We know where adults like to hang out, and we know where they breed, but there’s a gap in our knowledge for where they go and what they do between metamorphosis and adulthood.
The second was an adult Long-toed Salamander (Ambystoma macrodactylum), also hiding in the leaf litter at the base of a tree. I have seen Long-toed Salamanders in the water at night during the breeding season (January-February in our area) and I have heard many stories of them being found under plant pots on peoples’ patios, but I had never seen one out of the water. I had to double check the identification because the other terrestrial salamander that might inhabit the forest around Hazel Wolf, Western Red-backed Salamanders (Plethodon vehiculum), can look similar. Long-toed Salamanders have a distinctive yellow stripe along the middle of their backs (a dorsal stripe). Western Red-backed Salamanders also have a distinctive dorsal stripe; it tends to be more red or orange, though it can be yellow. Long-toed Salamanders are mole salamanders, “ambystomatids” and Western Red-backed Salamanders are lungless salamanders, “plethodontids”. The mole salamanders tend to be a bit chunkier in build than the plethodontids, which tend to be long and slender. Long-toed Salamanders also, as their name implies, have one toe on the hind foot that is longer than the others. The dorsal stripe on adult Long-toed Salamanders can tend to break up as it extends down the tail, whereas the dorsal stripe of the Western Red-backed Salamander remains solid to the tip of the tail. And the Long-toed Salamander, like its ambystomatid relative the Northwestern Salamander (Ambystoma gracile), has very distinct costal grooves or ribbing along its sides. Using those traits as my clues, I was pretty confident the find was a Long-toed Salamander adult.
We also found an adult Northwestern Salamander hiding in a channel in the soil along the path. Another mole salamander, Northwestern Salamanders are the species that lay those dense, oval egg masses that are usually wrapped around a stem or branch and tend to be visible long after they have hatched. The terrestrial adults are generally dark in overall color and they have two large parotoid glands on their heads, located behind their eyes. The really cool thing about Northwestern Salamanders is that they take two forms as adults. Some metamorphose and become terrestrial adults, like the one that we found. Those move into the surrounding upland after metamorphosis and hide in the substrate or under cover objects. The second form is an aquatic form. Those are neotenic or larviform adults that maintain their larval gills and remain in the water. They can be dark in color like the terrestrial form adults, but they can also have a variety of coloration, including a greenish background with dark spots. They occur in wetlands with permanent water. If you ever see a really large salamander with big, thick gills swimming around in the water, that’s a Northwestern Salamander neotene- a reproductive adult that kept its larval gills to take advantage of all the resources a permanent body of water can offer.
It is so exciting to be back in the field hanging out with amphibians again. I love that we have this opportunity for citizens to get involved with these fascinating critters. I’m looking forward to seeing how this program will grow and inspire even more intrepid amphibian enthusiasts, animal lovers, environmental stewards, budding scientists, and interested community members to join in the cause and the fun.
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