I believe that speciesism is correct. However I am confused about how I should feel about campaigns to kill pests like possums, rats, stoats etc which destroy native and often endangered birds, animals and plants. I understand that speciesism doesn't say that you can never kill an animal, you merely have to give it equal consideration. In this sense killing the pest could be justified if doing so produced a better outcome. But then I arrive at the problem of humans, which (I assume) would in many situations be a greater threat to our native birds, animals and plants.
I can't help but feel that the answer may lie in the fact that we can do something about humans which destroy the environment by convincing them we shouldn't, it's not as easy to reason with the average possum. However this seems inadequate given the fact that these people are very, very unlikely to ever be convinced. How can we justify killing pests in moral terms in light of speciesism?