Mystery Insect, need identification

["Mark Fischer" aguasonic]

Dear NR,

So, I recorded this insect last Spring on the banks of the Sacramento
River. The source was deep in brush, so I could never actually see
what was making the sound, and I am not that familiar with insect
sounds generally. It is posted in the 'Files' section as
'mar12_insect.mp3'. Does anyone knows what kind of critter makes this
sound?

Thanks,

Mark
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