奇速英语

New research has found that wells dug by wild horses in deserts provide valuable drinking water. This helps other animals too, as black bears and American badgers have been found drinking at the wells.

A team of researchers from Australia, Denmark and the US set up remote cameras at four desert locations in the US. Wild horses had used their feet to dig wells as much as two meters deep at these sites, so they could reach water under dry river beds and streams. The cameras were used to watch over the sites and were set to record whenever an animal moved in front of them.

The scientists saw plenty of comings and goings by horses but they were most interested in which other animals came to drink at the wells. Over the course of three summers, beginning in 2015, the team recorded 57 kinds of other large animals visiting the wells, including wild cats and deer. The team also found that the wells offered water to desert plants.

Researcher Erick Lundgren, from Aarhus University in Denmark, described the wild horses as “natural engineers”—animals that change the environment around them. Perhaps the best known natural engineers are beavers (河狸). Beavers cut down trees with their teeth, creating space in woods where sunlight can reach smaller plants and allow them to grow. Then beavers use the wood to create dams across rivers, which help clean pollution in water and protect their homes.

More than 12,000 years ago, several kinds of horse-related animals lived in North America but they all died out. Today’s wild horses develop from animals that were brought to America by humans in the past few hundred years. By digging wells that help other animals, they may be providing a similar service of natural engineering once given by their extinct relatives.