African savannah elephants need connected habitats for stability

In a study spanning 25 years, researchers have highlighted the crucial role of connected habitats in the conservation of the African savanna elephant. 

The extensive research, covering over 100 elephant populations in southern Africa, accounts for an estimated 70% of the global savanna elephant population, revealing a complex picture of population dynamics and conservation challenges.

“This is the most comprehensive analysis of growth rates for any large mammal population in the world,” said Rob Guldemond, director of the Conservation Ecological Research Unit (CERU) at the University of Pretoria.

Key findings

The study showcases a rare conservation win: the number of African savanna elephants has remained stable over the last quarter-century, despite the rapid loss of biodiversity globally.

However, this positive trend masks regional variations. Areas like south Tanzania, eastern Zambia, and northern Zimbabwe have seen severe declines due to illegal ivory poaching. Conversely, regions such as north Botswana are witnessing booming populations.

Long-term stability 

“Unchecked growth isn’t necessarily a good thing, however,” said Professor Doris Duke of Duke University. “Rapidly increasing populations can outgrow and damage their local environment and prove hard to manage – introducing a threat to their long-term stability.”

The researchers went beyond documenting local growth rates of African savanna elephants. They delved into the characteristics of local populations to decipher what factors contribute to their stability.

Elephant populations in well-protected but isolated parks is a concept often referred to as “fortress conservation.” The experts noted that in these isolated environments, elephants are safe from immediate threats like poaching and can experience rapid population growth. However, this rapid growth in confined areas is not sustainable in the long term.

Connected habitats

The research team determined that the most stable elephant populations are found in large, core areas with surrounding buffer zones. 

These core areas are well-protected and minimally impacted by human activities, while buffer zones accommodate controlled activities like sustainable farming or trophy hunting. Importantly, these core areas are connected to other parks, facilitating natural movement.

“What’s crucial is that you need a mix of areas with more stable core populations linked to more variable buffer areas,” said study lead author Ryan Huang, a postdoctoral researcher at CERU.

“These buffers absorb immigrants when core populations get too high, but also provide escape routes when elephants face poor environmental conditions or other threats such as poaching.”

Study implications 

The study underscores the importance of connecting protected areas. “Calling for connecting parks isn’t something new. Many have done so,” said Huang. “But surprisingly, there has not been a lot of published evidence of its effectiveness so far. This study helps quantify why this works.”

“Connecting protected areas is essential for the survival of African savanna elephants and many other animal and plant species,” said Celesté Maré, a doctoral student at Aarhus University in Denmark. “Populations with more options for moving around are healthier and more stable, which is important given an uncertain future from climate change.”

The study is published in the journal Science Advances.

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