Chasing night sounds

There are a lot of interesting sounds that are seldom heard except at night.  Not just bats and owls, but also a variety of insects: crickets, bush crickets, and beetles, to name a few.  The insects like warm nights, and so that’s also when you have more insect predators, like the bats.

It’s been really hot in the Sonoran desert lately.  Breaking records, which is not a good thing when you live in an already hot  climate.  It’s already been over 110 degrees F at my house, and there’s no end in sight to the high temperatures.

But the night calling insects seem to really be enjoying the warm nights.   A couple of weeks ago, I drove out to a lovely hidden canyon called Happy Valley, about 25 miles east of Tucson.  It’s isolated enough that the sounds of the interstate  and the railroad cannot be heard, so it makes a nice place to record.

In addition to wanting to record night sounds, I also wanted to test out my CR-V-to-camper conversion.  I’ve been wanting to ditch the tent thing for a while, and when I learned that a number of people had successfully turned Subaru Outbacks, Toyota Prius’, and even Honda Fits into small campers, I knew I could do it with my CR-V.  The details of the conversion are here.

On the first night in Happy Valley, I found a nice dispersed camping site near a wash and across from a wall of rocks.  It looked like a good place to record owls.  There was a teeny bit of water in the wash, left over from a recent rain.  Large sycamore, hackberry, and mesquite lined the wash.

It was pretty quiet when I arrived just as the sun was setting.  I set up the mics on the roof of the car, took the dog for a walk, and settled into the CR-V.  The crickets and owls started calling shortly after it got dark, creating a lovely evening chorus:

The crickets slowed down after midnight, but the owls kept calling well into the dawn chorus.   When I examined the spectrograms after I got home, I realized there were insects calling in the ultrasonic range, too.  But I had set my recorder on too low a sampling rate to catch the sounds, and I forgot my ultrasonic mic.  So I went back 10 days later and recorded another evening chorus, from the same place.   This time, the insects were much louder, so the birds (poorwills, screech owls, and Mearn’s quail) could barely be heard at all.

And sure enough, there was a lot of activity in the ultrasonic range.  Here’s a picture of the spectrogram, covering about 1.5 seconds:

Human hearing for youngsters only goes up to 20000 hertz (right hand vertical scale- just below the bush crickets).  The sounds labeled as “sonic crickets” are the crickets you can hear in the recording.  The spectrogram also showed some interesting stuff at the very top, above 80,000 Hertz.  It was faint, but I’ve never seen it before, and when I made another recording about an hour later, it was gone.  I suspect it was another insect calling in the distance.

Lots of cool things making sounds at night, if you stop to listen.

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