I don't really think it has anything to do with intelligence, but more about emotion. "Rights" are a human creation. If I ran into a hungry cougar in the woods (as in the big cat, not the human kind) who decided that I would be a good meal, it is doubtful that the cougar would stop to think about my rights. Humans, on the other hand, are driven by emotion in almost all that we do, and it would appear that we are the only animals who care about the rights of other animals.

I don't think it would be an intellectual decision if a human had to save a cow or a cat. I associate cats with my childhood, so I feel strongly about them. I don't really have any emotional connection with cows, so I would probably save the cat.