Fieldwork Fun: Day Two — Rare snails Can’t Slow Me Down


Adventures of a USFWS Summer Intern

By Hallie Morris, U.S. Fish and Wildlife Service Summer Intern

A beautiful river canyon can be seen with emerald green water and wispy clouds in the sky.
The beautiful Snake River, near Twin Falls. USFWS photo: Thomas Serrano

Continuing the adventure, my fellow intern and I woke up bright and early to travel to Twin Falls, Idaho. Our destination: Devil’s Corral to make some Gastropoda history!

The site, just above Shoshone falls, is pretty special because it is a natural barrier to many species. The canyon has two arms of spring-fed creeks that run through the site and drain into the Snake River. Additionally, because these two arms contain spring water, it makes the area the ideal habitat for our target shelled friend, the Bliss Rapids snail.

Everything about this snail is small: its size, population range, as well as public knowledge of the species. The snail, on average, is smaller than a pencil eraser and the younger snails can be as small as a point of a pencil. They are limited to areas with spring water from the Eastern Snake Plain Aquifer and are endemic to South-Central Idaho. Bliss Rapids snails require cold clear spring water from these areas to survive. They tend to be found in pockets near the banks where the water flow is slower. They are found under rocks of all sizes as they like dark places but do come to the top of rocks at night before moving back to the bottom when first light comes.

After a short snail identification training, we put on our waders and trekked into the waters. It was stinky and sinky at first because we had to get through the vegetation but then we hit our first pool. The survey work was especially exciting because this was the first time this land was surveyed in its entirety for these threatened snails and approximate population counts were unknown. A single pool at the head of the Western arm had been surveyed only to confirm presence of the snails because the land-owners only provided permission for a presence-absence survey. The land-ownership changed, and the new owner is very pro-snail! There is an interest to semi-develop the land into an ecoresort/learning center, snail conservation is also very important to the land-owner. We are all very excited that the land-owner loves these little critters as much as we do, and that he lets us see if his land houses our snail.

Travel can be challenging through the vegetation, steep slopes and under-water muck! USFWS photos: Thomas Serrano and Hallie Morris

It only took about five minutes to find the snail. I was lucky enough to be the first one to find said snails on a fairly big rock (after I double checked with our expert first). After that we found them all over the cobbled areas along the edges of the creek. We double-checked some areas that had white water to make sure we didn’t miss any, even though they are not typically found in fast moving water. Because bliss rapid snail presence is unknown in this area and because they are so rare, their tolerance for discharge rate (water flow) is not certain.

Alyssa Bangs gives the crew instructions on what to look for during surveys. USFWS photo: Hallie Morris

It took us all day but we made it through the first arm and made it to the edge where there was a waterfall that led the water to the Snake River. We found healthy populations of the snail which was very exciting! We also made note of an invasive species when we saw it, the New Zealand mudsnail. These snails can resemble the bliss rapid snail but are usually identifiable by the shape of their shell and how many swirls they possess. Bliss rapid snails are more round with few swirls, its shell color is also usually clear though can be a more red and even purple/pink. There were five of us to start and even the landowner and his lead contractor came in wetsuits and wanted to help! One of us kept track of data on a data sheet while the rest of us looked for the snails under the rocks. We picked up a rock making sure to note its location, flipped it over, then looked for snails. We counted how many we found then measured the rock in centimeters with our hands. After we yelled our information to the data recorder we gently placed the rock back where we found it to limit disturbance to the snails and habitat.

The field crew counts bliss-rapid snails on cobbles and records the data. USFWS photo

Day Two

POV: I’m starting to realize waking up early and getting a head start to the workday is very beneficial when you don’t like the heat and burn very easily (red-head problems).

Today we started our Bliss Rapids snail search on the Eastern arm. This arm already proved to be much more intense than yesterday’s trip. The owner watched us from way up above on the cliff, probably wishing us luck for the journey ahead. We started through a sinky marsh like the day before and hit a block so we went around by climbing onto scree (loose rocks that cover a mountain) and doing some makeshift rock climbing and boulder scrambling. Something new to add to the resume!

The canyon we scrambled down into the Snake River on day two was very rocky and dry. USFWS photo: Hallie Morris

Just when I thought things couldn’t get more challenging, I spotted our next obstacle: a waterfall with a cliff on one side and a more forgiving slope on the other. We chose the latter and made our way around the waterfall and butt-scooted down the slope to the water- another new skill to add to my resume! We were not surprised that we didn’t find Bliss Rapids snails at the bottom of a waterfall. We started bushwhacking through the vegetation until we found suitable habitat, and by vegetation, I mean poison ivy and stinging nettle at about every turn. We ended up finding a few snails in that area but not many and moved on. This arm was not very walkable in waders as there was so much vegetation and muck that made you get stuck; we ended up doing a lot more boulder scrambling and forging our own paths. All in all, we had to work really hard for the success of finding the snails here, and I fell, a lot, and got some nettle stings as well. It all seemed worth it because, in areas that were not so sandy and filled with bull rush, we found some pockets of the snails!

We made it through the spring-fed creek with a lot of sweat and grit. The arduous journey was worth it, however, as we found our snail friends and even some cool looking caves in which the water ran through as well. It felt nice to be by the caves and underground water areas as it provided a much needed chill, after a hard day’s work!

The river is on the left side of the frame and the canyon wall is on the right
The beautiful Snake River on a cool late spring day. USFWS photo: Thomas Serrano



USFWS Columbia Pacific Northwest Region

Conservation stories from one of the world’s most ecologically diverse regions.