Donkeys make a loud sound developed in order to maintain contact with other donkeys over wide spaces in the desert. This is called a bray. While donkeys in captivity have no need to stay in contact with other donkeys over space, they will still bray for a variety of reasons. Like dogs, some donkeys are more vocal than others. No technique will silence a donkey completely; but by understanding why these animals call, you can limit the frequency of these loud vocalisation.
Keep donkeys in groups or pairs. A lone donkey will bray more often than one kept in a herd or as part of a pair. Males are typically more vocal than females.
Install motion sensor lights to protect your donkeys from predators. A donkey will bray as a warning when it sees predators, such as wolves, coyotes or wild dogs. Motion-sensitive lights will scare off predators before the donkey sounds the alarm.
Maintain a consistent feeding schedule. Donkeys have strong internal clocks and may bray close to feeding time to remind their human about breakfast, according to Jean Patton with the American Donkey and Mule Society. If you feed your donkey at the same time each day, it won't need to remind you.