Dark-sided Chorus frogs have backs that look like leaves or mossy rocks but their sides are just dark brown. They come out in the evening and are awake all night. They make a clicking noise that some people like and others don't. I think it is relaxing to hear the sound of wildlife at night. Citation and more infomation at https://bangkokherps.wordpress.com/2011/12/27/darkside-narrowmouth-frog/
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From @mattt