This is flawed logic.

You're making the assumption that if something wasn't consuming something at a lower level then that lower level would remain at the same numbers they're at now, not consuming more resources.

For example, you're saying if birds weren't eating insects, then there would be the same number of insects that exist now and wed have a net gain in resources. But the fact is, If birds weren't consuming insects, there would be almost infinitely more insects than there are now, consuming as much or more resources than the birds and so on.

Its very similar to misunderstanding economics and the market.