Functionally referential calls refer to specific stimuli in the external environment of the caller and cause receivers to show an adaptive response to them. Here I have addressed some of the questions about the underlying cognitive mechanisms of functionally referential alarm calls, using as examples meerkats and a few other species. Several social species have evolved alarm call systems with either predator-specific or non-specific alarm calls, or both. Because meerkats emit the same alarm call types in response to different predators, but independent of the location in relation to shelter or the behavior of the caller, these calls are denotative. Whether this is typical of referential calls in other species has still to be tested. In some species, the predator-specific calls appear to refer to a predator species or category, whereas in others they refer to the spatial area from which the predator is approaching or its behavior. The question arises as to whether the sam
e cognitive mechanism underlies calls referring to the physical characteristics, the spatial position, or the behavior of the predator or whether different information processes distinguish these calls. When considering the different alarm call types with respect to the expression of the emotional state of the caller, the acoustic structure appears not to relate to the arousal of the caller in a simple linear way in all of the alarm call types. This suggests that the different referential and emotional components conveyed in the acoustic structure in the different species reflect more complicated mechanisms than a pure linear emotional system can explain.