The information that receivers extract from alarm calls in suricates
Field observations and acoustic analyses have shown that suricate (Suricata suricatta) alarm calls vary in their acoustic structure depending on predator type. In this study, we tested whether receivers respond appropriately when hearing a call in the absence of a predator. Although the only way for suricates to escape from predators is to retreat to boltholes, responses to playbacks could be divided into distinct categories. The subjects responded differently to alarm calls given in response to aerial or terrestrial predators and to recruitment calls emitted in response to snakes and deposits on the ground. Suricates also showed rather distinct responses to low, medium and high urgency aerial calls. Differences in the responses were less obvious for different levels of urgency in the terrestrial and recruitment calls. Suricate receivers thus gain information about both the predator type and level of urgency from the acoustic structures of their calls.
The invention provids a communication method, apparatus and system. The delivery source address registered in the delivery source address registration area 142 is a delivery source address corresponding to information delivered. The delivery source address corresponding to the general RSS information is registered and and a PC (10) also can obtain the RSS information (D1) for the client corresponding to a RSS reader (141) used in the PC (10).