Long (~4-6.5 second duration), typically powerful, throaty, Open-Mouthed, highly modulated rumbles that are associated with Head-Lifting, Listening, and rhythmic Ear-Flapping. With measured sound pressure levels. of up to 115 dB, elephants use these calls to keep in audible contact with one another over distances of 1-2 km. We refer to these vocalizations as Contact-Rumbles or Contact-Calls.
A Contact-Call sequence may include several rumbles: A caller's initial rumble is associated with rhythmic Ear-Flapping and is followed by Listening behavior: the caller's head is held in an attentive lifted position, Head-Raising, with ears cocked, Ears-Stiff, as if waiting for a response, and as if querying, "I am here, where are you?" An answering elephant typically responds with an abrupt lifting of the head and ears as if Listening and a sudden, explosive rumble seemingly stating, "I am over here.” This sudden calling is often unexpected to the human observer because the initial caller is often distant and her rumble, therefore, inaudible to human listeners.
The initial caller, upon hearing an answer, may respond with another call, often associated with a more relaxed posture, as if sending confirmation that an answer has been received. Nearby family members may also add their voice(s) to the second or third phase of the sequence, and calling back and forth may continue, intermittently, over hours until the individuals meet again.
Separated by long distances, elephants will Contact-Call with highly modulated rumbles at high sound pressure levels, but, as might be expected, elephants also call back and forth to one another over shorter distances with less modulated rumbles at lower sound pressure levels.
Adult females, juveniles and calves all make use of Contact-Calls. As far as we are aware adult males do not use the powerful long-distance version, but we would not be surprised to learn that adult males in tightly bonded groups do. Most Contact-Rumbles last between 4 and 6.5 seconds and are modulated in frequency contour, typically rising sharply at the start and falling more gradually. There exists a wide range of variation in the contours of Contact-Calls, however, that may be related to whether the individual is the initial caller or the one answering.
In 2002 McComb showed that the Contact-Calls of individuals are structurally distinct and audibly identifiable to other elephants. In other words, Contact-Calls contain an acoustic signature. It is possible that considerable additional information is contained in the different variations of the calls, perhaps related excitement level of the callers, their inter-individual distance, the sequential arrangement (i.e. call, answer, confirmation), or to logistical, or locational information or who, in particular, an elephant is directing its calling to. Future research may answer some of these questions.
References: Poole et al 1988, McComb et al. 2003; Poole 2011. (Full reference list)
This behavior occurs in the following context(s): Movement, Space & Leadership