>>9052I can't speak for Buddhism, but for the more literal reincarnation concept found in Hinduism, the idea is that your 'form' is a manifested expression of latent desires & actions articulated in your prior life, with the soul's preservation persisting beyond lives, as a means through which the corporeal earthly form can then articulate itself, varying with each iterative life in terms of its permutations and its expressions.
So, to answer your question, an animal would be 'judged' (it is not judged though, this is a Christian preconception/bias that I think you seem to have which is carrying over and clouding your understanding of an unrelated paradigm. It is merely expressed in its subsequent life as an altered extension, or evolution/mutation of its previous life, beholden to no 'grand moral arbiter', only beholden to the varieties of character) according to its prior actions in its specific form, there would be no external standard which is extricated from it and applied to it, as it is only itself interacting with the universe, part of a whole which is the network of expressions found in the various forms of life/existence. For example, a Sloth is, by design of its species, a certain 'way', but the particularities of that 'way' are what grant insight into the unique character of that form, and which may influence the subsequent form the sloth will take on, but the 'way' itself, i.e. being a sloth, is also its own standard, and speaks not to some eternal quality of the soul, but as a latently manifested expression of particularly exhibited characteristics found within one's previous life. So, a sloth which is less lazy than other sloths typically would be by nature is, for example, already somewhat 'different' than the normal sloth, and so is less likely to reincarnate into something 'sloth-like' in subsequence. It is also possible, therefore, to reincarnate into the same thing repeatedly–part of the process of enlightenment consists in traveling through different forms throughout numerous lives, of apprehending a universally holistic perspective which can only ever be truly attained by having experienced all those facets of the universe piece by piece.