Rights, really, are something that us as humans have made up and applied to ourselves, through our own conceived thoughts of morality. Whether animals have rights depends entirely on whether we think they should have rights, and then apply those "rights" to them, whatever they may be.
No but neither does humans. Human rights are purely fictional, in reality only power decides what is right or wrong.
Or put in another way; whatever you do is right as long as you have the might to back it up/ get away with it.
It does not matter how moral or immoral the action actually is.
If you have the power to massacre ten million people then you have the right to do so if you wish.
Power gives you the right, because power = right.