
1) Animal communication 2) Emergency communication
Found on
https://www.crosswordclues.com/clue/alarm-signal

In the field of animal communication, an alarm signal is an antipredator adaptation referring to various signals emitted by social animals in response to danger. Many primates and birds have elaborate alarm calls for warning conspecifics of approaching predators. For example, the characteristic alarm call of the blackbird is a familiar sound in ma...
Found on
http://en.wikipedia.org/wiki/Alarm_signal

in zoology, a ritualized means of communicating a danger or threat among the members of an animal group. In many cases the signal is visual or vocal, ... [2 related articles]
Found on
http://www.britannica.com/eb/a-z/a/38

A communication made by animals to alert others to the presence of a predator or a potential predator. May be visual, vocal, olfactory, etc.
Found on
http://www.encyclo.co.uk/local/22217
No exact match found.