Are killer whales persons?

I think it's based on the idea that the rights of an individual are based on the intelligence or capability of the species he's part of. Thus a single human wouldn't be singled out for lacking any of these as it's a still a human, thus treated according to human rights.

I realize that the answer is sometimes "yes", but I don't think that crimes against humanity (orca-kind?) or rendition agreements are applicable in this case.

There is no precedent for making it illegal to refuse to risk your health, well-being and bodily integrity to sustain another person with your own body. If the risk is negligible, sure, everything else would be denial of assistance -- but pregnancy (to say nothing of birth) is extremely risky as far as biological processes go.

You could argue about a voluntary pregnancy being some kind of contract that suspends your right to bodily integrity but that still wouldn't apply to unwanted pregnancies, which represent the majority of abortions.

Arguing that a foetus' personal rights are violated by early stage termination of a pregnancy is just special pleading biased by religious ideas about the inherent sanctity of life. Most nefariously, the same people who argue for the rights of a foetus also oppose the welfare that would be necessary to address the social impacts of the unwanted birth. Or to put it more hyperbolically: "A human's life is holy, until they are born".

Should orcas be legal persons? Probably not. They can't give consent and will never be able to, in principle. This is different from a mentally underdeveloped human or a human child because an orca will neither grow up to be able to give consent nor could they reach that capacity as a species (within human timeframes).

Could orcas evolve to become legal persons? Maybe, but there isn't any selection pressure guiding them in that direction.

We should however acknowledge that "personhood" is not a well-defined requirement for the rights we grant to persons. We should probably extend some of those rights to certain animals independently of whether we can consider them persons or not. They're autonomous and have some form of sentience -- it seems only fair to acknowledge that in how we treat them.

That aside, the real debate here is animal rights and what constitutes animal cruelty. Personally I think Sea World is criminally abusive because it is necessarily incapable of holding large water mammals like orcas in captivity in a way that minimizes suffering for them -- the tank size alone could not be large enough for that; the economics just wouldn't work out.

Captive pygmy killer whales are really nasty also. They howl loudly (like wolves) and actively charge against humans when in the same pool. They need open and deep water so is understandable.

Bootlenose dolphins could hit and kill easily an human but probably only if seriously injured or restrained (or if a baby dolphin is in serious danger). Dolphins seem to be really smart and friendly even in the most dangerous situations for humans. Most are very curious with pregnant women for example. Could be really easy for the dolphin to kill the human foetus in this situation with a couple of hits of the beak but this never happens. To try to 'rape' humans is a much more frequent behaviour in male bootlenose dolphins (Not, I'm not joking).

Common dolphins probably not, their beak is too much fragile to take the risk to harm an human. A dolphin with a break mandible is a dead dolphin.

Ziphiidae probably could kill easily a human. They have the character and the strenght, although no case has been recorded I think... humans normally don't share the same space than beaked whales and its sharp and big frontal tooth. I did not advice to try to swim between two males figthing anyways.

Pygmy sperm whales are not aggresive for humans even when injured or stranded, and I'm really happy with it. They will readily defecate over you instead and I can personally assure that is a very sticky red jelly thing but you really don't die for this.