Call combinations in monkeys: Compositional or idiomatic expressions?

► Putty-nosed monkeys produce different call sequences to external events. ► Sequences consist of two call types, concatenated in context-specific ways. ► One sequence consisting of 2-8 calls and including both call types, is given prior to group movement. ► Sequence length but not the relative contribution of each call type affected listeners responses. ► The sequence is not compositional but is holistic and more analogous to an idiom.