IWANIUK, A.N.; DEAN, K.M.; NELSON, J.E.; Monash University, Clayton, Australia: Comparative neuroanatomy and evolution of parrot brains (Aves: Psittaciformes).

The advanced cognitive abilities of parrots have been recognized for several decades. Little is known, however, regarding the neural substrate responsible for these advanced abilities. Given that they appear to be cognitively convergent and share a number of socioecological similarities with primates and cetaceans, they should possess similarly sized brains and brain regions subserving advanced cognition. Furthermore, since the same cognitive abilities have not been found in other avian species, parrots should have relatively larger brains than other birds. Using a data set of 190 species, we demonstrate that parrots do have much larger brains relative to their body size than any other group of birds. Also, despite the supposed constraints posed by a volant lifestyle, the relative brain size of parrots is not significantly different from that of primates or cetaceans. In fact, a number of parrot species have relatively larger brains than comparably sized primates. Detailed volumetric analyses of brain structure within a subset of parrot and primate species also reveal similarities between the two groups in the relative size of the telencephalon and its constituent components. The two groups differ markedly, however, in how their brains are organized. The results yield some insight into the functional organization of the avian brain as well as the evolution of advanced cognitive abilities in general.