The ability for humans to create seemingly infinite meaning from a finite set of sounds has likely been a critical component in our success as a species, allowing the unbounded communication of information. Syntax, the combining of meaningful sounds into phrases, is one of the primary features of language that enables this extensive expressivity. The evolutionary history of syntax, however, remains largely debated, and it is only very recently that comparative data for syntax in animals have been revealed. Here, we provide further evidence for a structural basis of potential syntactic-like call combinations in the vocal communication system of a group-living songbird. Acoustic analyses indicate that Western Australian magpies (Gymnorhina tibicen dorsalis) structurally combine generic alarm calls with acoustically distinct alert calls to produce an alarm alert sequence. These results are distinct from previous examples of call combinations as, to our knowledge, evidence for this capacity is yet to be demonstrated in the natural communication of a non-human species that is capable of vocal learning throughout life. These findings offer prospects for experimental investigation into the presence and function of magpie call combinations, extending our understanding of animal vocal complexity.