Likely natural, nature does this often.
Hail storms or a tornado that picks up gravel or even hypothermia can explain the birds.
As for the fish there have been Drum kills due to a viral infection all around the country first notced in 2003, but they have happened before, and will happen again.
If you’re looking for doom and gloom, it can be found in nature without looking very hard, and most of it isn’t due to Us at all.
NO ONE can sell newspapers, or get web site hits with THAT kind of attitude...
expect to be ignored...