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DZANGA! CENTRAL AFRICAN REPUBLIC

Overview
Much of what we know about forest elephants comes due to the persistence and dedication of Andrea Turkalo at this forest clearing. Her sustained presence at this field site, and her sincere relationship with the local Ba' Aka population, have probably been the most important factors in keeping poaching to a minimum at the Dzanga clearing. We owe an incalculable debt to Andrea and her commitment to forest elephants.

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Here's a lovely video clip of the elephants in Dzanga Bai. In addition to occasional elephant rumbles and African Grey Parrots, you can hear Andrea identifying elephant families.

Adult elephant and infant in Dzanga Bai, CAR

© Andrea Turkalo

 

In 2000-2002, ELP's research efforts were focused at the Dzanga forest clearing where up to 100 elephants gather daily. Andrea Turkalo, a member of ELP, has studied the elephants in this clearing for over 18 years via support from the Wildlife Conservation Society and other grants. During this time, Andrea has identified over 3000 elephants using the clearing. Thus, Andrea’s expertise on the elephant population at Dzanga and the high concentration of elephants made this site the ideal location for comparing elephant vocalizations with counts of elephants in the clearing (Figure below) and for determining the distance over which elephant calls travel. Calling elephants were identified by localizing the source of sound via an acoustic array (under 'Deeper Explorations' at right, follow the thread about 'arrays').

Recording units, placed along a 1 kilometer line going into the forest, recorded the progressive reduction in sound intensity. This information has allowed a statistical model to be developed to predict the area over which elephant calls can be detected surrounding a single recording unit. Results from Dzanga suggest that low frequency calls could be detected up to 860 meters corresponding to 2.3 square kilometer area of detection surrounding a recording unit.

Developing Methods to Count the Unseen

Forest clearings, like Dzanga, provide the rare opportunity to actually observe forest elephants and their interactions with one another. Although clearings, called 'bais' by Central Africans, are scattered throughout the Congo Basin, forest elephants spend less than 5% of their lives in these openings! Most of the time they are roaming the rainforest in small groups, often just mom and her dependent offspring, looking for fruits and succulent browse, or traveling between resources such as bais. Scientists also know very little about what proportion of a local population of elephants actually visit the forest clearings.

Developing a method to count animals, to estimate populations, in habitats where they are not easily seen has been a driving force behind the research of the Elephant Listening Project. Taking advantage of the visibility and high density of elephants at Dzanga, Mya Thompson and co-workers quantified the relationship between number of calls and number of elephants (below).

Graph showing direct correlation between number of elephants in Dzanga Bai and the number of calls they made This relationship between elephant numbers and calling rate was used very successfully to estimate the size of an elephant population in Kakum National Park, Ghana (follow the thread to 'Kakum' in panel at right to learn more).