Interesting questions, Sentosa. As I mentioned, I am a panpsychist and therefore believe that animals have souls, as does all of matter. Even atoms have tiny minds. I have been critical of traditional Chritianinity and Western thought for ascribing the soul exclusively to humans. I am reminded here of Descartes, who thought animals were mere soulless, feelngless machines. I believe that attitude has been responsible for much exploitation of the environment. I argue panpsychi9sm fits well with evolution, for two reasons. First, there is no hard-and-fast dividing line between the organic and the inorganic, the living and the nonliving. Secondly, what is the case at the top of teh scale is also the case at the bottom, though to a significantly lesser degree. We have been so busy extending mechanical principles up the scale, to explain things, that we have forgotten to extend psychological principles down the scale, to equally explain things.
Where is the soul? I would identify the soul with the entire organism. Mind and matter are one, in my metaphysic. For higher organisms, I would say that if you want to see the would, it is the size and shape of the nervous system and brain. I also think it important to consider whether we are talking of a soul (singular) or souls (plural). I think a tree consists of souls, but has no brain, no dominant member in charge. It is more like a leaderless democracy. Organisms with brains consist of souls, the cells, for example, but also have one soul in charge. So there is no tree spirit, but there are tree spirits.