Alton C. Byers, CAS Visiting Scholar and Research Associate at INSTAAR has authored an article about the impact mules are making on the Everest Trail. In the article, Byers writes that "[The mules] have largely replaced the use of dzopkio (yak-cattle cross breeds) for the Lukla to Namche supply run, although dzopkio and yak continue to be used from Namche onward to the higher altitudes. On a recent walk from Phakding to Lukla there well over 100 mules in trains averaging about 15 animals each.
The locals hate them because mules destroy the trails with their sharp hooves, and leave behind so much poop that one seemingly spends more time playing hop scotch than trekking. Worse, they seem to think they have a right of way on the trails. Dzopko and yak always seem to go out of their way to avoid making any kind of contact with humans. But not mules."
Read the full article here.