the cambridge declaration only makes it formal: non-human animals exhibit consciousness.*
The neural substrates of emotions do not appear to be confined to cortical structures. In fact, subcortical neural networks aroused during affective states in humans are also critically important for generating emotional behaviors in animals. Artificial arousal of the same brain regions generates corresponding behavior and feeling states in both humans and non-human animals. Wherever in the brain one evokes instinctual emotional behaviors in non-human animals, many of the ensuing behaviors are consistent with experienced feeling states, including those internal states that are rewarding and punishing. Deep brain stimulation of these systems in humans can also generate similar affective states. (...) Evidence of near human-like levels of consciousness has been most dramatically observed in African grey parrots. Mammalian and avian emotional networks and cognitive microcircuitries appear to be far more homologous than previously thought. Moreover, certain species of birds have been found to exhibit neural sleep patterns similar to those of mammals, including REM sleep and, as was demonstrated in zebra finches, neurophysiological patterns, previously thought to require a mammalian neocortex. Magpies in articular have been shown to exhibit striking similarities to humans, great apes, dolphins, and elephants in studies of mirror self-recognition.
*The group consists of cognitive scientists, neuropharmacologists, neurophysiologists, neuroanatomists, and computational neuroscientists -- all of whom were attending the Francis Crick Memorial Conference on Consciousness in Human and Non-Human Animals. The declaration was signed in the presence of Stephen Hawking, and included such signatories as Christof Koch, David Edelman, Edward Boyden, Philip Low, Irene Pepperberg, and many more.