I think animals have no rights....and then neither do humans. I don't consider us being in anyway unique in nature. Sure we can think, and we are a lot more intelligent than the rest of the 'animals', but that is just because we evolved that way....our ancestors were animals after all.
So if we are animals, and we are all the part of some big foodchain (and are presently on the top I think) than we are free to kill and eat anything. So 'naturally' speaking animals have no rights and neither do other humans. The fact that we made laws to protect ourselves from our own kind is different.
On the other hand, once can also say that since we are evolved enough we ought to show compassion for life and stop killing....be it animals or other humans.
But I don't think this middle way makes much sense.....you killing considerately, taking into consideration the endangered species and stuff.....I mean how many species have already become extinct? Had nature really wanted to preserve them (or God, if you will) then it would have happened by itself....we would have still had the mammoths around....
This habit of man trying to play God is just not right in anyway. Killing animals but still trying to keep the species alive......I mean what's the point? All species will become extinct one day! If one is so concerned about nature and her works then stop killing all together.....or else forget conservation.
Just my two cents.