[Edited]
Not all humans have an ability to reciprocate by carrying out obligations. It’s true in general that rights imply obligations, but it doesnt have to be true in every case. Thats not implied by the fact that it has to be true in some cases. So you can offer rights to entities that can’t reciprocate. But you don’t have to offer them the full panoply. For instance, in most societies, minors have limited rights and obligations. So animals don’t have to have a full set of rights, including the right to vote , or, more contentiously, the right to die of old age.
[Edited] Not all humans have an ability to reciprocate by carrying out obligations. It’s true in general that rights imply obligations, but it doesnt have to be true in every case. Thats not implied by the fact that it has to be true in some cases. So you can offer rights to entities that can’t reciprocate. But you don’t have to offer them the full panoply. For instance, in most societies, minors have limited rights and obligations. So animals don’t have to have a full set of rights, including the right to vote , or, more contentiously, the right to die of old age.