By Ashley Burke, CBC News Ottawa, January 23, 2017
Thousands of crows have descended on the capital, gathering in trees and filling the air with a cacophony of cawing in a daily ritual that's giving some residents the creeps. Experts say the birds are merely meeting up for nightly roosts, an avian slumber party that actually occurs each winter.
Nevertheless, some people witnessing the phenomenon for the first time are surprised and — in some cases — downright frightened.
http://www.cbc.ca/news/canada/ottawa/american-crows-ottawa-roost-social-media-1.3948044