As happens every year, certain parts of the office parking lot have become unusable because they are under tree branches… and there’s a roost here that must have several thousand crows every night.
Why do crows roost?
And for that matter, why do roosters crow?
Two reasons,
-
Safety in numbers
-
For some reason that area is warm
I asked the very same thing a few years ago.
To repost my answer from the thread linked to above:
Some of the reasons crows and other birds may roost together at night:
-
Protection from predation. Predators that try to attack an individual may be mobbed and driven off by many members of the group acting together. Also, a few members of the group are likely to be awake at any time of the night, and can give warning.
-
Information sharing. When birds take off in the morning, those that found food the previous day may be followed by others. (And possibly can be distinguished by their quickness in leaving in the morning.)
-
In cold climates, birds can huddle together for warm during the night.
Also: flying around in the dark is dangerous if you are a bird not specifically adapted to it.