This isn’t being investigated due to the bird. It’s due to the illegal parking in a bike lane. Someone died a week or so ago in Toronto due to a construction bin being left in the bike lane.
By saying 1 sigma, they are basically saying tgat are 68% confident in the results. As you increase the sigma, your confidence in the results increases. Here is a site that goes into more in depth explanation:
https://news.mit.edu/2012/explained-sigma-0209#