AVIAN MOVEMENT IMITATION AND A NEW FORM OF MIMICRY - TRACING THE EVOLUTION OF A COMPLEX FORM OF LEARNING

1. The spontaneous imitation of movements, previously known in two orders of mammals, is demonstrated in a psittacine bird. 2. The animal, a Grey parrot which has bonded to humans, utilizes its torso, legs, wings, head, beak, and tongue in the imitation of human movements. 3. A new form of imitation, ''non-vocal mimicry,'' is tentatively identified. It is defined by the use of skeletal movements to produce mimetic sounds. 4. Hierarchical relationships and phylogenetic patterns of occurrence suggest that imitative learning in birds may have evolved through the sequence: song/call learning --> vocal mimicry --> non-vocal mimicry --> movement imitation. 5. These relationships and patterns, and possible differences in function and incubation time, suggest that movement imitation in birds is not homologous to that in mammals.