This order includes all species of parrots, parakeets, cockatoos, amazons, conures, macaws, lovebirds, etc. They are tropical birds, often very colourful, with morphological features that easily distinguish them from other groups of birds. They have a thick hooked beak, zygodactyl legs with digits II and II opposite to digits I and IV giving them a good grip, and a muscular tongue. The anatomy of the beak, tongue and skull allows them to use it very skilfully. They are highly intelligent animals, with great learning abilities, and are capable of complex vocalisations that mimic environmental or human sounds. The ratio of body mass to brain mass is comparable to that of the great apes in some cases. Psittaciformes are geographically close to Passeriformes.