I had a person once that wanted to discuss the topic of whether animals where able to agree or not and if sex between humans and animals would be legitimate... That conversation did not last long.
Generally this conversatĂon is a non starter. But: can dolphins consent?
I mean they don't care about you consenting since they're rapey AF but - "person-like" animals such as orangutans, dolphins, corvids, could probably offer consent in a manner that's ethical.
I don't think anyone should fuck any of the above, or even could fuck a corvids, but there are legitimate implications in ethics of an animal is capable of consenting to anything.