“...just as though I had turned off a switch. It was time to go to sleep, obviously.”
We got the opposite problem in the cities. Birds are programmed to be quiet at night (except for mockingbirds), but since cities have streetlights and other lights on all the time, the birds get confused and sometimes chirp away all night long.
Where I am the birds wake up at 4 AM this time of year. Our yard sounds like an aviary.