Secondly, there is no such thing as an animal being treated ethically if it's in captivity. All animals should be left in their natural habitat; the wild.
Anyone, that goes to a place where an animal is being held prisoner cannot say that they are a vegan.
Got to come back to this.
1. The first sentence is too general and thus wrong. Maybe you mean "wild" animals? And even then, what about rescued wild animals that are unable to go back into the wild for various reasons?
2. Your second sentence reminds me some "vegans" on reddit. Very self-righteous and judgemental. And your quoting the vegan philosophy is simply dogma. We should be treating animals with respect. Not abusing or eating or wearing or testing etc. The rest... whatever. I've never liked dogma, not religious dogma and not dogma that, in the end, a person or persons simply came up with. For the most part, I'm vegan, and whether anyone like it or not, that's generally how I will describe myself. But I live in a non-vegan world, so some of my opinions will likely not match those of the fundamentalists.
Morality is for the most part subjective and ethics are open to change over time.
In general I disagree with zoos. But whilst we live in a non-vegan world, they can be a source of education. No, I don't particularly want to fund them, but it can be a great learning exercise for kids if done correctly.
And I do agree that we need to keep endangered species alive. With any luck in the future, mankind will see the error of its ways and if these animals have vanished from the wild, then that's it...they are gone.
If we can draw back from all the land we use for "livestock", go through a re-wilding process then maybe, just maybe we can bring some creatures back from the brink of extinction.