- Wild donkeys & horses engineer water holes that help other species. Often cast as invasive pests, the equids may actually benefit some ecosystems. Equid wells can act as desert oases, providing a major source of water during dry times that benefits a whole host of desert animals & keystone trees. https://www.sciencenews.org/article/wild-donkeys-horses-ecosystem-engineer-water-holes-invasive-species 399 comments science