Wow ..... I've been hearing them ( the chirps, trills) as well and also 
wondering what they might be.  I've noticed them most often in the early 
evening in our meadows when I head out to do evening horse chores.

Mundi
Pownal

Also, has anyone been hearing some chirps in the night? The past 2 
nights I have around 2:00 to 3 am (I am often insomniac). Couldn't ID by 
voice...anyone else hear this or some thoughts about what it might be??Wow