Voices in the forest

Last October, the dog and I took a lovely hike down Summit City Canyon, near Carson Pass in the Sierras.  I last hiked this canyon more than 40 years ago, and remembered it as one of my all-time favorites.  The only problem with it is that there is no easy way to get there.  Most trails going in require a long, steep descent into the canyon, which means a tough hike coming out.  But the scenery – steep granite walls over a conifer forest lining Summit City Creek – made the hike worth it.

We started at Upper Blue Lake, and crossed a low divide before heading into the canyon.  From there it’s all down hill.  We hiked the steady, sometimes steep, grade along the creek for several miles, dropping about 1300 feet from the divide.  It was a brisk day, after a heavy frost the night before, and the shade of the large fir trees kept it cool.  We found a nice sunny rock to stop for lunch, just as a flock of chickadees and nuthatches were moving through.   Fall tends to be pretty quiet, so I’m always pleased to eavesdrop on the conversations of wild critters.

I set up my recorder, and the dog and I stretched out in the sun and listened as the mountain chickadees and white-breasted nuthatches chattered on and on as they foraged through the area.  Just as their sounds were fading away, a Douglas’ squirrel gave a territorial call and a few moments later started an alarm call.  It was too far away (I think) to be reacting to us, so something else must have triggered it.  Summit City Creek whispered in the distance, and I enjoyed listening to the changing sound of the creek as a light breeze in the trees made the creek sound closer, then further away.  Then I started hearing the “cluck” call of a chipmunk, which is a response to a hawk or other bird of prey.   There are something like 6 species of chipmunk in this part of the Sierra, so I don’t know which it was.  They tend to separate by elevation/habitat, but there is a lot of overlap, and most people agree that they are difficult to tell apart.  Some species can be told by their vocalizations, but I’m guessing all respond the same to the alarm calls.  Chipmunks, and many other squirrels, have different alarm calls for different types of predators, hawk vs. coyote, for example.  This chipmunk was telling everyone nearby that a hawk had just passed through the forest (they don’t start calling until the hawk has moved away).  So much going on, if you are willing to listen to the voices of the forest!

When I last took this trail, my friend and I backpacked all the way down the canyon to the confluence with the Mokelumne River.  It was a rough trip, as the mid part of the trail is solid granite steps – each about 4-6 feet high, next to lovely pools as Summit City Creek cascades its way over a long series of small waterfalls.  The trail was also lined with thorny wild rose bushes.  They’ve closed the lower part of the trail now, so you can no longer hike to the confluence.  This saddens me, even though I doubt my old knees could handle the trail anymore (that saddens me even more).

Nature sound recordist Lang Elliot did his Master’s thesis on Eastern Chipmunks, and knows their vocalizations well.  He recently wrote a blog post about them, including a great recording of chipmunks chorusing an alarm call:  https://musicofnature.com/the-clucking-munks/

For some videos that illustrate the calls of Douglas’ squirrels, see: https://youtu.be/QDO1JuCoAZs

And check out my earlier blog post about the differences in alarm calls among social vs. non-social squirrels.

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