Alarm calls, communication and cognition in Australian magpies ('Gymnorhina tibicen')

Alarm calls have served a model function to test hypotheses about intentional signaling as an integral, if not key element, in the expression of higher cognition. The alarm signals of sonic avian species. including alarm and distress calls. may be generalized and so be understood by mammals and other birds. Some species, including primates and ground-dwelling mammals, have developed specific alarm calls that convey meaning beyond communicating a general state of arousal or fear. They indicate specific types of predators, for example ground or aerial. Similar distinctions in alarm calls had been shown only in one avian species, the domestic chicken. I investigated the alarm calls of Australian magpies in the field and found that magpies may use as many as eight well-defined types of alarm calls, only one of which is used for a general alert. This was used in playback experiments. I also identified a specific alarm call that seemed to be reserved for birds of prey alone: recordings of them were taken in response to wedge-tailed eagles. The same alarm calls were then used experimentally in playbacks to oilier groups of magpies. The results demonstrate that magpies respond differently to this alarm. suggesting that they may also use referential signaling.