As the skylarks fall silent, an ultrasonic din begins

Sandy, Bedfordshire As the birdsongs of day fade out, the bat detector stirs into unheard actionThe sun had risen over fields of oats and gone down on a prairie of stubble, yet still the skylarks sang. Though the world beneath their wings had been transformed, they continued exulting or lamenting in twilight overtime. I listened to two, three, or many voices intermingling at the fading of the day, but whether they sang in the sky or gave their evening show from the ground, I could not tell.Other