Wild horses and burros roaming the American west is an image that many of us hold dear, representing the romance of freedom as herds gallop across the deserts of Arizona, Nevada and California. But if you ever wondered how they survive in such an arid landscape, a new study shows that horses and burros are very adept at “ecosystem engineering.”
The study set up camera traps at five sites in the deserts of Arizona and California and captured images of the wild equines digging wells for water. Using their front hooves, they expertly moved sand and dirt backwards until water was unearthed as deep as six feet down. The horses and burros provided themselves with much-needed water, but also created an environment for other wildlife to drink. In fact, the study found the freshly-dug “equid wells” provided water to an astounding 57 species of wildlife including birds, black bears and badgers.
Well digging by wild donkeys and wild horses in the Sonoran Desert, USA. (Photo credit E.J.L.)
The researchers studied the results of the camera traps every two to four weeks over the course of three summers. The team also set up cameras at locations without wells, to act as scientific controls. The diversity of species seen at the equid wells was 64 per cent higher than at the control wells, which pointed to the fact that the wildlife intentionally visited the equine-made wells. According to the study, the researchers also located open water sources in the areas surrounding their camera traps and discovered that the horses and burros increased accessible surface water density by up to 14-fold.
National Geographic interviewed the lead author of the study, Erick Lundgren, a postdoctoral researcher at Aarhus University in Denmark who referred to the equid wells as “hotbeds of animal activity.”
He also made the observation that the equine well-diggers demonstrate an intrinsic value to native wildlife. Wild horses and burros have long been held in contempt by some ranchers and conservationists who view the animals as an invasive species. The study proves the animals add value to the ecosystem and perform a vital service to native flora and fauna, and might go some way to convince the Bureau of Land Management that controls the herds, and other critics, that the horses and burros are worth preserving.
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