If you hear a rumble in the jungle it's probably just the elephants talking

We might be a long way from talking to the animals, but according to Joyce Poole, when it comes to the African elephant, we are starting to understand them. Wachira Kigotho reports.

Like the fictional Dr Doolittle, Joyce Poole may one day be able to speak to the animals - or the African elephant at least. Poole, principal researcher for the Kenya wildlife service, has spent more than 25 years studying this mysterious and ancient mammal in Kenya's Amboseli National Park and has discovered that it uses powerful low-frequency sounds to communicate - some inaudible to the human ear. This has led hunters and naturalists to wonder at how separate groups of elephants can coordinate their movements over vast distances and in dense forests.

Poole's discovery and her attempts to document the elephant's vocal repertoire have presented new avenues for her long-term work on understanding their complex social structures and behaviour.

With Karen McComb, another expert on the species, Poole had earlier mapped how the basic building block of elephant society is the family unit, comprising several females and their offspring living together under the close surveillance of a matriarch figure, usually the oldest female in the group. They show how members of each family unit feed, rest and move in a coordinated manner and have close, friendly ties with each other. They form alliances against aggressors, share responsibilities for young elephants and defend each other in times of danger.

The next level up the social ladder is the bond group - groups of families comprising between five and 50 elephants. Membership is predetermined, but elephants do not have to be genetically related. Although the ties among the bond group are less strong than those within a family, bond-group members are also close and behave in a friendly way towards one another, forming alliances against common aggressors and assisting in the care of each other's offspring.

Above the bond group is the clan, made up of several bond groups. The two researchers have defined an elephant clan as families who use the same area during the dry season. "Families tend to use their own clan area when resources are scarce. During times of plenty, members who belong to a specific clan can be seen together in large social aggregations," Poole told a recent workshop run by the Kenya Museum Society in Nairobi.

However, while females and immature elephants appear to live in a state of caring and sharing, the same is not true of the mature male, whose life is rigidly structured. The male leaves its nurturing family when it is 14 years old and begins a solitary existence filled with learning a whole set of rules based on pecking order in the rank of the other adult males in the population.

Poole says young males' transition to adulthood is gradual and may take up to eight years, because male elephants continue to grow throughout their lifetime and rank is based on body size. Because of their long life span, males are well aware of the size and strength of most of their rivals and by the age of 30 they begin to experience a period of sexual aggression, which often manifests itself in fighting.

Interestingly, the two researchers observed that during sexually inactive periods, males interacted in a friendly way, in places known as "bull areas". "But, during the sexually active periods, males leave these areas and interact with one another aggressively," Poole says.

On top of these social structures, the African elephant, possibly more than any other non-human animal studied, has built a complex labyrinth of relationships within and between families, bond groups and clans, between individual males and between males and females. This multi-layered network of relationships has been established, defined, nurtured and reinforced through an intricate communications system, Poole says.

Years of eavesdropping on elephant conversations, often using sensitive low-frequency detectors, has enabled her to attach specific meanings to different calls. Poole has, for example, decoded how different feelings are expressed by vocal signals. "Within each family, bond group or clan, different pressures come to bear and the use and frequency of different calls are indications of the importance of those pressures," she says.

For instance, the survival of females and their offspring depends on the cohesion and coordination of the extended family and on their ability to compete with other groups for scarce resources. For this reason, most of the calls made by females and juveniles emphasise the importance of team spirit.

Usually family members use calls to reinforce bonds between relatives and friends, to take care of youngsters and to reconcile differences among friends. Other calls concern the formation of coalitions against aggressors and attempts to maintain contact between family members. By painstakingly following elephants over long distances in Amboseli and Laikipia, Poole has found that male survival and reproductive success depends on a bull's ability to detect sounds made by others and to advertise their sexual state, identity and rank through sound.

Invariably, the African elephant makes a broad range of sounds that vary from high-frequency trumpets, snorts, screams and barks to roars and cries. However, the jumbos also produce another category of calls, usually known as "rumbles", that Poole has found contain more detailed information. The term "rumble", came originally from hunters who referred to some of these low-frequency sounds as "stomach rumbles" as they presumed that they emanated from the elephants' digestive tracts. "Now we know for sure that these rumblings are vocalisations, produced not in the intestines, but in the larynx," Poole says.

Describing rumbles as "harmonic sounds", Poole says she has so far identified and decoded 30 different rumbles. "Some of these are completely inaudible to human beings even at distances of only a few metres, others are heard as soft purring sounds, while still others are heard as powerful thundering roars," she says.

Each rumble has its own character and carries specific information on the elephant's needs, desires and dislikes. For instance, a calf uses a suckle rumble to tell its mother: "I am hungry, I need to suckle." A juvenile also uses a specific rumble to tell another young elephant: "Let's go this way." However, its friend may disagree and retort with another rumble: "No way, I don't like what you are doing. Leave me alone for now."

Elephants also communicate through question-and-answer rumbles, such as "I am here, where are you?" and "Please come this way. I am over here." Poole says she has identified some specific rumbles that signify the sexual state of the African elephant or that carry information about a particular elephant's identity.

Some of the more interesting rumbles seem to contain instructions for other elephants or involve achieving consensus within the group. "On several occasions, I have observed an adult female initiating the calling," Poole says. "She may change direction or activity as she begins to call and I believe that information is contained within the call."

Poole says African elephants are some of the best team players in the animal kingdom. Apart from living in cohesive family units, they respect their leaders and negotiate with one another. They are also capable of charging at the enemy in a coordinated attack.

In her efforts to decode their language, she has found that females are more talkative than males - of the 30 known rumbles, adult females make six times as many as males.

The study of elephant communication requires a lot of patience, but Poole believes it might eventually force us to confront our traditional beliefs and understand the emotional, social and intellectual complexity of these extraordinary mammals.