Rutting calls of male and alarm calls of female red deer (Cervus elaphus), sika deer (C. nippon), and their hybrids were recorded from wild and captive-bred populations. Vocal variations between these species and their hybrids (C. elaphus × C. nippon) were examined using multivariate analysis to determine whether these groups could be successfully discriminated. There were highly significant differences between the vocalizations of each group for both sexes (males: Wilks' Λ = 0.0233, P<0.0001; females: Wilks' Λ = 0.1338, P<0.0001). The greatest differences were between analogous calls of red and sika deer. Vocalizations of hybrids from both captive-bred and feral populations were intermediate between the two parent species. The differences between the groups were most highly influenced by the pitch of calls. The results of this study indicate that the vocalizations of deer, rather than being learned or mimicked from similar species in their proximity, are strongly influenced by the genetic background of their parents.