This post makes an unusual argument that spells out a line of reasoning occurring first at an intuitive level. It is about free will and maybe what one might call "humanity" but in the context of animals.
Now, it is generally granted to animals that they have feelings, including not only physical pain and pleasure but also emotions such as sorrow or joy. On the basis of their so-called "sentience," it is sometimes argued that they have a right to compassionate treatment, regardless of whether they possess the faculty of reason.
And, to be sure, there have also been arguments and studies supporting the idea that animals also, to a greater or lesser degree, possess reason and are not thoroughly governed in their behavior by the dictates of instinct. For example, a chimpanzee trying to reach a bunch of bananas in a cage may stack some boxes on top of each other in order to reach said bananas, thus employing ad hoc strategic thinking -- which we may call reasoning -- in the process.
So it would seem valid to say that animals possess sensations, emotions, and (to a greater or lesser degree) elemental reasoning. Those that possess a greater reasoning power -- which we call "rational" to that extent -- are also implicitly seen to be closer to human beings in the capacity for free existence. That is, freedom is equated with simple logical reasoning.
Yet even the above attributions do not capture the sense of wonder I experience sometimes when paying attention to animate beings, such as birds, fish or even spiders and other insects. Observing the movements of a pigeon, I can sometimes find myself inwardly exclaiming, "This here is a free being!" And I'm led to this conclusion to a large extent by having a strong vicarious sense of the emotional experience of the creature. Intuitively, it seems clear to me that a pigeon or a cat or a dog that engages in play -- that is, creative self-entertainment -- must be a free being. But it is not just the capacity for logical reasoning that makes a being free (indeed, by that logic perhaps robots would be free). Rather, I would say, their freedom consists in their search for self-knowledge -- for greater awareness about how certain experiences excite or affect them (which cats and dogs show in their occasional attempts, when solitary, to play the part of both prey and predator within the same make-believe drama, dogs for instance often by trying to catch their own tails). The same way human beings may re-play events that have come to pass several times over in their minds, in order to mine the memory for greater understanding of the self or of things in the world, animals will playfully re-enact events they experience in the sudden and turbulent state of nature in order to gain further knowledge and a stronger sense of identity.
But it is not only in the experience of play that I believe this freedom is revealed. The other day I was observing some minuscule fishes in a pot (where the fishes are a side-show to some plants growing out of the pot) on the balcony. After throwing some fish food into the pot, I was observing the greed of the larger fish, which not only ate a (typically) disproportionate share of the food -- even taking into account its own larger mass -- but wanted to prevent the smaller fish from eating anything even after it was no longer able to eat further itself. What struck me the most was witnessing the excruciating dilemma the smaller fish faced, as they would often speedily approach a little morsel of food, only to reconsider often in the very course of taking a bite, out of fear (sometimes justified and sometimes not) that the big fish was approaching them, and quickly abandon the food. Having to make a decision in the midst of the contrary pulls of desire and fear seems to me to be the power only of a free being. Only a free being can have strong feelings about its own relationship to other things, and arbitrate over those feelings when deciding how to act.
To sum it up, I think freedom is demonstrated not above all in the simple use of logic but in the search for a deepened understanding of the self and of one's relationship to the world, and in the continuous negotiation of desire with reality. Animals may not be quite as free as humans, but the vividness with which world experiences affect them, and their ability to arbitrate between opposing motivations surely earns them some status of free, self-aware being.