What Is That?

One of the things that I really love about my home is the virtual cacophony of nature noises that surrounds it in the spring and summer. At night, it's all frogs and crickets and in the morning and throughout the day, it's non-stop birds.
My favorite is the cardinal that sounds like he's ordering Mexican food all day long. Burrrr-rito! burrito! burrito! burrito!
Recently, however, there is an unpleasant sound. It woke me up yesterday and today. It made conversation difficult yesterday afternoon. It is a loud clicking chirrup kind of noise, almost like someone keeps half-squeezing a really loud squeak-toy. No matter how hard I try, I can't put my eyes on what creature is making the noise though it is definitely coming from the trees.
I guess, though, that if you want a noisy backyard, you have to take the good birds with the bad.