Eco Engineers: 5 Animals That Can Reshape Earth's Waterways


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Elephants
African elephants transform the landscape and waterways in multiple ways. Wim van den Heever/Getty Images

It's hard to keep a full belly when you weigh 7 tons (6.35 metric tons). African elephants are larger than life and have appetites to match. On a typical day, an adult will spend 12 to 18 hours eating, devouring as much as 600 pounds' (272 kilograms') worth of food in the process. All that munching is vital to the ecosystem. So are the bowel movements that come later.

Elephant dung is a nutritious fertilizer for the soils of Africa; it's also a vehicle by which many seeds are dispersed. Furthermore, by knocking down trees and eating shrubs, these colossal animals convert forests into grasslands.

A 2009 study revealed even more about the transformative powers that African elephants have over their habitats. Appearing in an issue of the journalBioScience, this study reported on the ecosystem engineers in Botswana's Okavango Delta. Elephants, the co-authors noted, are great at building water channels. The tusked herbivores like to cover the same land routes over and over again, making trails in the process. Sometimes, multiple generations of elephants will re-use the exact same footpaths. As time goes by, the heavy animals can't help but compress the soil, turning their walkways into trenches.

According to study authors, when elephants move back and forth between two bodies of water, their sunken trails become nice conduits. Thus, rivers or ponds that were once isolated can be merged via elephant-made canals.

And that's not the only service that elephant routes provide. In 2010, environmental scientists Roy Sidle and Alan Ziegler published a seven-year study on an Asian elephant trail in northern Thailand. By inspecting both water and sediment levels, they determined that this pathway helped send monsoon runoff directly into the local streams.

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