I live in a two-story house on a ridgeline, overlooking a valley. The house is about 400 feet above the valley floor. The hillside is fairly steep, and my back yard is fairly narrow before going downhill in a hurry.
There are air commuters in our neighborhood. Hundreds of local crows live atop the hill, in a forest behind my place. In the morning, they all fly down to the valley where, apparently, the food pickings are easier. Every night, just before sundown, they fly back up the hill to the forest.
I was awakened this morning by some odd rattling sounds from my roof. I got out and went into my office (which has a fine view of the valley) to try to figure out what was going on.
As is usual in the winter around here, heavy fog had formed overnight. Visibility was probably 100 feet or less.
The noise? Dozens, if not hundreds, of crows lining up on my gutters. In groups, they'd launch off the roof and start gliding downhill like they normally do. Then they'd get 50 or a hundred feet out, and realize they were losing contact with the ground.
You'd see masses of black birds leap off downhill, fading out into the fog, then there'd be an explosion of wings as they abruptly turned around and headed back to the safety of the roof. There were 2-3 groups, and they were all basically flying in a big circle.
Pretty wild to watch....
Ron Wanttaja