A couple of years ago, I happened to be talking with a herpetologist who asked me to make the sound (which I only barely can, a super-fast high-pitched warble), and he declared it a tree frog. Apparently, they can go through their entire egg-tadpole-legged life cycle in 24 hours, given nice deep rain puddles. Viola! Frogs inland from water, like charming, noisy mosquitoes. They might wake me, but I much prefer them to their winged counterparts.