The complexity of animal vocal communication has now become an important topic in ecology and evolution. A number of studies have shown that many animals produce conspicuous mobbing calls when encountering predators of their offspring near their nests. However, we still know little about the function and information content of these calls. Here, I show that mobbing calls of great tits, Parus major, transmit referential information about predator types to both parents and nestlings, thereby eliciting different adaptive reactions in them. Great tit parents produce acoustically distinctive mobbing calls for the two main nest predators, the jungle crow, Corvus macrorhynchos, and the Japanese rat snake, Elaphe climacophora. Playback experiments revealed that parents respond to the two types of mobbing calls with different predator-searching behaviors. Nestlings respond to them with different predator avoidance behaviors. Together, these findings may not only improve our understanding of anti-predator adaptations in brood defense, but also provide insights into the evolution of complex referential communication with multiple receivers.