Contextual sources of information and responses to animal communication signals.

The response of signal recipients depends on information found in the signal itself and on other information sources known collectively as context. Context is the set of events, conditions, and changeable recipient characteristics that modify the effect of a signal on recipients' behavior. Sources of contextual information include (a) the characteristics of the recipient and (b) sources external to the recipient (the signaler and the setting). Contextual information is most commonly used when the signal itself does not provide enough information for the recipient to behave adaptively. The signal's referent may be ambiguous or deceptive, or recipients may need additional information to fine-tune their responses. When animal signals were thought to be information poor, contextual information was seen as being critically informative. Animal signals are now known to be much more informative, but even information-rich systems, such as human language, depend heavily on contextual sources of information.