A team of engineers from Walt Disney World recently invented a new technology that makes it possible to better under stand low-frequency 'rumble' vocalizations among African elephants. In the past, it has been very difficult to differentiate the low-frequency calls between individuals. This has made it nearly impossible to study the low-frequency calls that are essential in short-distance communication and spontaneously occurring vocal exchanges between individuals. The Disney World Company Instrumentation Support Division of Ride and Show Engineering built transmitters that were mounted in elephant collars that recorded the elephant's vocalizations.
Joesph Soltis and his team of researchers used these collars to collect vocal data from six female African elephants living in Disney's Animal Kingdom. They wanted to determine whether low-frequency vocalizations could help scientist's understand the social context of the calls and whether they are related to reproductive behavior.
There was strong evidence gathered from the vocal data to show females did not randomly produce low-frequency rumbles, but were almost twice as likely to produce a rumble after another group member rumbled. The affliliative relationship with another caller had a strong impact on vocal response.Females were much more likely to 'respond' to a rumble made by a partner it had the longest relationship with, compared to those it had not known as long. Dominance rank and reproductive state did not have any affect on whether or not an elephant would respon. Elephants also were shown to rumble in certain social contexts; such as when animals were out of contact, when they reunited, or when they were close to each other.
Soltis and his team followed up this study by making quantitative acoustical measurements on a large set of captive African elephants, and attempted to build on prior research on categorizing types of rumbles. What their analysis showed is that vocalizations could not be divided into subtypes, as there was a large amount of variation across rumbles. A commonly proposed function of these rumbles is a long-distance contact call between African elephant females. When related females are out of contact, they may use these calls to localize other individuals and coordinate their movements. The results of Soltis’ study show that female rumble vocalizations are each unique, and that elephants can recognize each other by voice alone.
All of this data shows the wide spectrum of uses the African elephants have for their low-frequency rumble call, and this is just the tip of the iceberg. There is a lot of research that still has to be done to better understand the subtle differences and meaning of the different calls, and also to understand the many other methods elephants use to communicate.
Joesph Soltis, Kirstin Leong, and Anne Savage. "African Elephant Vocal Communication I: antiphonal calling behaviour among affiliated females." Animal Behaviour. 70 (2004):579-587.
Joesph Soltis, Kirstin Leong, and Anne Savage. "African Elephant Vocal Communication II: rumble variation reflects the individual identity and emotional state of callers." Animal Behavior. 70. (2004):589-599.
I love how a team from Disney World is part of this research- and it got published in Animal Behavior at that! Its interesting to read how this signal is used in the population and how the females respond to it. Do the researchers write anything about any physical behaviors the elephants do when they respond to these calls, i.e. do they move closer to the signaler or is the response merely one of ‘Yes I hear you and I’m responding, ‘Hello’?” Do they also incorporate stomping feet into this audio signaling?
ReplyDeletePosted by Christine Rega
This is a very interesting post especially because it shows that these rumbles may have multiple meanings and may even convey individual identity. I was surprised to learn that responses were related to relationship rather than dominance. Did the article talk of any other behaviors being exhibited during these calls? Also was any frequency analysis done that could maybe separate rumble types and figure out their individual meanings? It would be interesting to see if these calls have categories and if individuality is conveyed within these categories so that the receivers of the message know who is trying to communicate.
ReplyDeleteAwesome post!
Posted by Jackie Connolly