Part of why the “natural” angle is so hard to argue strongly is that you can use it to advance almost anything as a right, by selecting which parts to highlight. Is defense a right, or is safety—what self-defense seeks—a right? These are very different things, and it’s not clear that either’s more-correct nor that they’re wholly compatible. Does the animal defending itself prefer to defend itself, or would it rather not need to in the first place?
This is the kind of trouble one gets into with these analogies-from-nature, or with the kind of fictional humanity-in-the-state-of-nature stories that used to be in vogue for “proving” which things are or are not natural rights: they’re usually superfluous, because we’re just using motivated reasoning to reach the same conclusions we would have if asked to list what we think ought to be rights without that foundation. Instead of discussing which outcomes are likely and preferred by protecting some set of rights, we waste time deciding which set of from-nature analogies or tales are valid (if we go down this road and find that holding slaves is a right—what then? But we won’t, because the whole thing is just motivated reasoning anyway, so we’ll pick some different set of stories to ensure we don’t end up there—repeat for everything else)
This is the kind of trouble one gets into with these analogies-from-nature, or with the kind of fictional humanity-in-the-state-of-nature stories that used to be in vogue for “proving” which things are or are not natural rights: they’re usually superfluous, because we’re just using motivated reasoning to reach the same conclusions we would have if asked to list what we think ought to be rights without that foundation. Instead of discussing which outcomes are likely and preferred by protecting some set of rights, we waste time deciding which set of from-nature analogies or tales are valid (if we go down this road and find that holding slaves is a right—what then? But we won’t, because the whole thing is just motivated reasoning anyway, so we’ll pick some different set of stories to ensure we don’t end up there—repeat for everything else)