What happens if the herons food source disappeared?

Imagine the world without owls the world would never be the same. Owls produce owl pellets and without owls there would be no owl pellets. Owl pellets are the leftovers from an owl's food. Owls eject these pellets by throwing up. We study these pellets to learn about vermin anatomy and owl diets. Without owls we wouldn't learn about these things. We know owls eat vermin but if owls were extinct then there would be an up rise in vermin population. Most people do not like vermin and wouldn't be happy about even more vermin running around. Not only do owls eat vermin they also eat small birds occasionally. Owls could be released into New York City to help the vermin problem. In fact one owl eats about 4 mice per day that is 1460 mice eaten by an owl per year.