The contribution of "outdoor cats" to the decline of bird populations is well known.
A rough estimate is that, in Canada, in the order of 100 million bird deaths are caused by cats per year.
Nature Canada has created the Cats and Birds initiative to combat this problem; for details see https://catsandbirds.ca
The initiative is supported by various local organizations,
including Nature Alberta, Wild North, the Edmonton Animal Care and Control Centre and your Edmonton Nature Club.
Consider taking the Pledge to Keep Cats Safe and Save Bird Lives at https://catsandbirds.ca/join-the-movement.