Parrots have shown the ability to interact with tablet-based speech boards to engage in parrot-human communication. However, the influence of speech boards’ interface design on avian usability and, thus, on speech boards’ potential to optimally support parrot-human communication, is yet to be explored. As a first step in this direction, we report on a longitudinal four-year in-the-wild study of a Goffin's Cockatoo's interactions with three successive speech board interfaces. The study explored, for the first time, possible relations between interface design variables typically considered for human speech board users - type, granularity, repertoire and arrangement of speech board representations - and the bird's selections under different conditions and across different design iterations. Based on our findings, we contribute key considerations and hypotheses to inform further research into the relevance of interface design choices for the avian usability of speech boards and, thus, their potential to optimally support functional parrot-human communication.