To pile on, the average weight of male Canadian Geese is > 8 pounds, which is higher than the largest 'large bird' that needs to be tested, and they travel in flocks. I think they worked out that each engine probably ingested two birds. At the time those engines were certified, the largest bird tested was 4 lbs and they only volleyed them into the outer area of the engine, not the core where the accident engines hit.[1]

Now they have to send them into the 'most critical area' of the engine, but depending on engine size the largest bird tested could still be 4 or 6 lbs.

[1] https://www.ntsb.gov/investigations/accidentreports/reports/...