With about 10,000 species, birds make up one of the most diverse classes in the animal kingdom. While one may be enchanted by the prehistoric-clawed hoatzin, the sashaying mating dance of the albatross, or the colorful flash from the bib of the Anna’s hummingbird, the parrot dazzles in various respects, making it one of the most extraordinary species to study. With the skill to visually stun anyone, coupled with its impressive intellectual potential, the parrot captivates humanity most through its ability to mimic human words. Why does the parrot speak? How can it speak when other songbirds—and animals—cannot? By delving into the structure, function, and genetics of the parrot brain, we can increase our understanding of this unique ability. While the causes of mimicry still remain a mystery, many theories pose promising hypotheses for this parrot trait, perhaps bringing us closer to understanding the complicated ins and outs of our own speech and its development.

Songbird Song Systems

The investigation into the curious nature of the parrot’s vocal ability starts with an analogous group of bird species with a similar talent: the songbird. While songbirds cannot mimic speech, they boast an impressive song learning system that is similar to the backbone of parrot speech structure.  [1]  This system consists of seven distinct nuclei with corresponding pathways that guide song production in the brain.  [2]  These nuclei are dubbed “song nuclei” and each have different specialized tasks.  [1]  The seven song nuclei are allocated into two major vocal pathways: the anterior forebrain pathway, which is in charge of vocal learning, and the posterior descending pathway, which is in charge of vocal production.  [3]  These pathways allow for communication between specific avian brain areas.

The pathway that is most relevant to this discussion is the “song learning” or anterior forebrain pathway. This system passes information through the following song nuclei: first the HVC, directly to Area X, then to the DLM, next to the lMAN, and finally returning to Area X.  [2]  Initially, the posterior descending pathway processes the sound that the songbird would like to imitate, then the sound is sent through the anterior forebrain pathway and travels through the song learning loop. The song is processed again in the nucleus HVC.  [3]  This information is then relayed to Area X, which stores a template of the song to be used as a source of comparison later. Next, this information is passed to the thalamus, which relays the signal to the lMAN, which acts as an editor for the song. This edited version is then passed back to Area X for comparison, where the song is further refined in the songbird’s learning. The information will be relayed back and forth from the lMAN to Area X until the song is perfected. Finally, when the song has been mastered, it is sent to the arcopallium (also known as the RA), located in the posterior descending pathway, which controls the motor movement of the muscles that enable song production.{[3]  Finally, the songbird produces song.