The ability of horses and donkeys to dig for water in dryland ecosystems can provide important benefits to other species, researchers have found.
Erick Lundgren and his colleagues, in a study titled Equids engineer desert water availability, noted that large animals play important roles in the biosphere, yet little is known about how they shape dryland ecosystems.
“We report on an overlooked form of ecosystem engineering by donkeys and horses,” they wrote in the journal Science.
In the deserts of North America, the digging of wells of up to 2 meters to groundwater by wild horses and donkeys increased the density of water features, reduced distances between water sources, and, at times, provided the only water present.
The number of animals and their level of activity were higher at these wells than at nearby dry sites, the study team observed.
“Our results suggest that equids, even those that are introduced or feral, are able to buffer water availability, which may increase resilience to ongoing human-caused aridification,” they concluded.
Sometimes, in providing the only water available locally, horses and donkeys aided a wide variety of plant and animal species and ecosystem processes.
Essentially, the horses and donkeys were providing a service that could bolster resilience for a wide variety of desert species.
For their work, Lundgren and his colleagues surveyed several sites in the Sonoran Desert of North America.
They observed well-digging by the region’s wild horses and donkeys, and found evidence of the benefits they provided to several native desert species.
Abandoned wells also occasionally became nurseries for important tree species, they noted.
A more detailed account of the research can be read here.
Equids engineer desert water availability
Erick J. Lundgren, Daniel Ramp, Juliet C. Stromberg, Jianguo Wu, Nathan C. Nieto (deceased), Martin Sluk, Karla T. Moeller, and Arian D. Wallach.
Science, 30 April, 2021, pp 491-495 DOI: 10.1126/science.abd6775