Humans make a LOT of trash and much of it is discarded food that they can scavenge. I suspect that the variety of animals such as crows and rats and their large

Humans make a LOT of trash and much of it is discarded food that they can scavenge. I suspect that the variety of animals such as crows and rats and their large population sizes is directly correlated with the growth of humanity. I don't think they would exist in such large numbers without us, basically.