What term describes the behavior of an animal which warns others that a predator is approaching?

Communication signal

Animals send communication signals not only in their species but also in other species to warn each other against a predator. Usually animals uses following signals to communicate

a)Visual – these are  of two types namely badges and dispaly

b)Auditory/sound base – This includes barking, growling, purring etc.

c)Chemical (release of any chemical)  

d)Tactile ( touch based)