Galapagos Species Database

Taxon category: Accepted

Origin: Introduced - established

Year of first record: 1834

Mode of introduction: Intentional

Introduction Pathway: Intentional

Subpathway: Animals for breeding

Introduced status: Naturalized

Invasive status: Invasive

Impact in Galapagos: There is little information regarding the harmful effects that donkeys independently caused in the Galapagos Islands. However, it is known that the donkeys and goats led to a severe degradation of habitat in Isabela, Floreana and Santiago islands. They were the main threat to plant diversity, responsible for the extinction of endemic species like Blutaparon rigidum, in the Santiago Island and Hyptis gymnocaulos (no record in the last 20 years) in the Alcedo volcano. Moreover, they predate on endemic plants such as Opuntia galapageia (Santiago Island), Opuntia insularis and over 180 native species in Alcedo volcano (Isabela Island). The endemic animals like tortoises and land iguanas, are also affected by competition for food and trampling of nests.

Impact elsewhere: The feral populations of Equus asinus are causing harmful and potentially irreversible effects on flora and fauna worldwide. Damages are documented in plants, soils, wildlife, and water quality. Of particular concern is the competition for forage, which adversely affects native species in areas where they occur. An adult donkey consumes about 3,000 kg of foliage per year and wild herds reproduce at an alarming rate which means an increase in foraging intensity. Grazing affects communities of plants that are displaced by other non-native and therefore the animals that depend on them are also displaced, affecting the habitat more. Donkeys cause erosion with their hard hoofs, damaging sources of fresh water, and introduce weed through seeds that they carry in their paws, fur and mane.

Control History in Galapagos: The Galapagos National Park conducted sporadic control of wild donkeys in Santiago Island since 1970, putting the biggest effort during the pig eradication campaign in 1995-1996 through hunting, which resulted in the largest number of slaughtered donkeys. The systematic aerial (helicopter) and land hunting in 2004 with pilots, hunters and specialized rifles, successfully eliminated the last wild donkeys of Santiago Island and Alcedo volcano in northern part of Isabela Island. Aerial hunting is highly effective in the elimination of donkeys in open areas. Its size, behavior and lack of hiding places make them very vulnerable.

Control methods elsewhere: Managers of wilderness allocate annually large amounts of money to control the population size of feral donkeys. Wolf traps are used to capture them, and farms are prepared to transfer the captured animals. However, the most effective method to control these animals is the aerial hunting, especially in open habitats. The fertility control has been suggested as a non-lethal method, but at present its use is limited. The techniques of fertility control are difficult to manage, it is also necessary to repeat the treatment to be effective. However, whether this method is effective in reducing the environmental damage caused by donkeys in areas of high conservation value has not evaluated.

Known Pest elsewhere: Considered an invasive species where they occur in the wild outside native range.

Prevention options: Prevent animals from escaping from farms into wild areas. Do not leave the animals abandoned in the field when hunting, thus avoid the donkeys from becoming wild again.

Preference for an altitude zone in Galapagos: Dry zone - high altitude dry zone

Habitat preferences: Equus asinus is distributed worldwide. The original habitat of the donkeys are the hills and deserts of North Africa and the Arabian Peninsula, which is why they are well adapted for life in the desert and in regions with low rainfall. Being an exotic species they have managed to adapt virtually to all vegetation types, with higher incidence in xeric shrublands, grasslands, thorny forest, coniferous forest and tropical forests. In general, this species prefers warm places and dry climate with little rainfall and sparse vegetation.

Feeding preferences: They are herbivores. They graze on grass and browse of leaves and stems. Its stomach is suitable for eating hard desert grasses such as Panicum and Lasiurus. Donkeys have a strong digestive system, not prone to colic, this allows them to consume a variety of plants and extract water from food very efficiently. Donkeys need little amount of food, allowing them to survive in inaccessible and difficult areas.

Trophic role: Herbivorous

Persistence mechanisms: Their adaptation to desert and arid habitats, its resistant stomach that allows it to eat hard grass, eating little food, little water and even resist mineralized waters, makes them successful in inhospitable and inaccessible terrain. Their good ear allows them to be alert to predators, defend giving heavy blows with their front and hind legs, they can even get to bite if it is to defend. They are long-lived animals, females can reproduce approximately for 20 years, and males mate throughout their lives, ensuring healthy populations in the places where they occur.

Reproduction mode: Exclusively sexual

Reproductive biology: Donkeys reach sexual maturity at two years old, and they can mate at any time. Once the female gets pregnant, breeding gestation lasts between 12 and 14 months. They will usually produce one offspring per litter, although there have been cases of twins. Offspring drink milk from the mother for six or nine months; once they have weaned, the mother is ready to bear offspring again. The female will have a calf every two years for 20 years. The donkeys can interbreed and produce a mule, this hybrid breeding is sterile. When the young reach sexual maturity, they are separated from the herd, but the bond with the mother remains.

Distribution origin: Africa

Distribution classification: Subtropical

Natural enemies: The severe drought and wildfires are significant natural threats for donkeys. They are an alternative to native predators like coyotes, pumas and jaguars. In Europe, the donkey is considered threatened species and is now under the protection of the European Union.

Economic Use: E. asinus used to be very valuable, prized for its strength, ability to work and low maintenance costs. Since it was domesticated it was used as a pack animal, it played an important role in the development of trade paper, mining, transportation of people, as a source of food (meat and milk), in cosmetics (milk) and medicine (blood, fat, organs, hair, hoofs, urine and feces), and used to treat a number of diseases (fever, jaundice, paralysis, epilepsy, pneumonia). Currently its value and use have fallen. The miniature varieties are the most sought after either as pets, or for children to ride and tour. In some developing countries, they are still used as beasts of burden, but less and less often. Some farmers use the donkey as a watcher, able to detect the presence of predators more easily than cattle, and bray strongly warning both farmers and animals.

Map of specimen collection localities or observation records for this species in our collections database.

Distribution: Originally present on Floreana, Isabela, San Cristóbal, Santa Cruz and Santiago Islands. It was eradicated from Santiago Island, Alcedo volcano on Isabela Island, and Floreana Island.

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