Blue herons are a bane to pond owners.
They regularly kill ducklings and wound/kill large fish that they cannot possibly eat.
They rarely get accepted to rehab facilities due to thier propensity to stab folks in the eyeball.
If you ever find a wounded one, approach with EXTREME caution. They will wait until your eyes are within spearing distance and will show no mercy.
I have been training otters to attack them on site. Results are mixed.
The trick is getting the otter conditioned to sweep the safety off smoothly upon presenting the pistol.