Sociality generates many cognitively demanding challenges which are often hypothesised to drive cognitive evolution. Previous research on the Western Australian magpie (Cracticus tibicen dorsalis) has established a robust relationship between group size and cognition. However, the mechanisms driving this relationship remain unclear. My research uses cognitive testing and social network analysis to investigate whether the group size-cognition relationship is driven by the complexity of intragroup interactions. I will also conduct vocal analysis and playbacks to investigate whether the group size-cognition relationship is underpinned by the need to communicate effectively in large groups.