Equus asinus
System : Terrestrial
Kingdom
Phylum
Class
Order
Family
Animalia
Chordata
Mammalia
Perissodactyla
Equidae
- General
- Distribution
- Impact
- Management
- Bibliography
- Contact
Common name
asino (English), ass (English), African wild ass (English), burro (English)
Synonym
Similar species
Summary
Equus asinus (donkeys) resemble horses and are characterised by their large head, long ears and cow-like tail. They can be found in tropical savannas and arid hill country in Australia and other arid and desert habitats elsewhere in its range. In its invasive range, Equus asinus have deleterious and potentially irreversible impacts on native flora and fauna. Damage has been documented in plant communities, soils, wildlife and water quality. Management of this species can be difficult. Cultural pressures prevent lethal methods of management from being used. Typical management techniques involve removing the species from their natural habitat and placing them in reserves where they will not pose a threat. The growing number of feral donkeys, roaming free across Sudan, Eritrea and Somalia propitiate extensive hybridisation with their wild relative Equus africanus and thus contribute to the extinction of the E. africanus.
Species Description
Equus asinus resemble horses and are characterised by their large head, long ears and cow-like tail. Colours can very from black, white, paint and all shades of brown and grey, however the most common is a mousey grey colour (called dun grey). Many E. asinus are spotted, speckled or striped. Most solid-colour E. asinus have a dark dorsal stripe from mane to tail and a dark stripe across their shoulders. They have an erect mane and lack the forelock of a horse. The hair can be straight, curly, short and wiry, or long and woolly. Wild E. asinus average 200cm in body length, 45cm in tail length, 125cm at the shoulder, and weigh 250kg. Domestic breed size varies greatly, depending on breed. Miniatures, the smallest breed of E. asinus, stand less than 92cm (36 inches) at the shoulder and weigh less than 180kg (400 pounds). Standard E. asinus, the average-sized breed, range from 92cm to 123cm (36 inches to 48 inches) and weigh 180 to 225kg (400 to 500 pounds). Mammoth stock, the largest breed of E. asinus, stand at an average height of 143cm (56 inches) and weigh about 430kg (950 pounds). There is generally very little sexual dimorphism in E. asinus. Wild E. asinus have the longest and narrowest hooves of any Equus species (Huggins 2002).
Notes
Rudman (1998) states that in the United States, \"Equus asinus populations are descended from domestic donkeys, who are in turn descended from the African wild ass. The social organization of E. asinus can therefore be compared to that of true wild asses as well. One population inhabits the Death Valley area of California. This region is a large open desert characterized by a harsh temperate climate and hyperdispersed vegetation but with a few permanent and reliable water sources (Moehlman, 1974 and Moehlman, 1979). E. asinus population in Death Valley exhibits no long-term social bonds except those between mother and offspring. Breeding is seasonal and dominant males are conditionally territorial. The other population lives on Ossabaw Island off the coast of Georgia, which is a small, relatively flat island with plentiful donkey food and water resources and a mild temperate climate (Moehlman, 1979; McCort, 1980). These donkeys live in either harem bands consisting of multiple females with offspring plus one or more adult males or in multiple adult male groups (bachelor herds). Breeding is non-seasonal and harem males defend territories year-round.\"
Lifecycle Stages
Female Wild Equus asinus give birth to one colt each year, which grows to an average weight of about 350 pounds. Since feral E. asinus have no natural predator, competitor or common diseases, most young E. asinus reach maturity and may live as long as 25 years in the wild (Royo UNDATED).
Uses
In Australia Equus asinus serve as pack animals and in haulage teams. E. asinus played a very important role in developing long-distance trade in Egypt, because of their weight-bearing capacity and their adaptation for desert travel. In ancient Egypt, female E. asinus were kept as dairy animals. E. asinus milk is higher in sugar and protein than cow's milk. The milk was also used for cosmetic and medicinal purposes. E. asinus meat was eaten as food by many people. There were domesticated E. asinus in Europe by the second millenium B.C. and the first E. asinus came to the New World with Christopher Columbus in 1495. E. asinus were introduced to the United States with Mexican explorers. Many of the wild E. asinus in the southwestern United States are descendants of escaped or abandoned E. asinus brought by Mexican explorers during the Gold Rush. Miniature E. asinus are very popular as companion animals and for show (Department of the Environment and Heritage 2004; Huggins 2002).
Habitat Description
Huggins (2002) states that, \"Domestic Equus asinus are widely distributed and can be found almost everywhere in the world. However, true wild E. asinus originated in the hilly, undulating deserts of northern Africa and the Arabian peninsula and are well-adapted for life in the desert. Domestic E. asinus prefer warm, dry climates and, if left to become feral, they will return to such a habitat, like the feral E. asinus of Death Valley National Park in California. Deserts are characterized by low, unpredictable rainfall and sparse vegetation.\"
The Department of the Environment and Heritage (2004) states that in Australia, \"Feral E. asinus prefer tropical savannas and arid hill country. Drought and severe bushfires are the only significant natural threats to feral E. asinus.\" In Europe, the donkey is considered to be the most threatened livestock species and is now under protection of the European Union and its measures to conserve local animal resources.
Reproduction
Feral and free-ranging E. asinus have a territorial social system (McDonnell 1998). The composition and degree of stability of territorial groups varies with particular populations studied. In some populations, each breeding male holds his own territory through which solitary females with their young pass (Woodward, 1979). Jennies in estrus are bred by the breeding male holding the particular territory. Populations have been identified in which jennies tend to stay within particular territories and have a more stable affiliation with the breeding male and other jennies in the territory, in a semi-harem type territorial breeding group (McCort, 1980). In some populations, there are groups in which subordinate males are allowed to breed some of the jennies within the territory of a dominant jack, usually following mating by the dominant jack (McCort, 1980). Territorial boundaries appear to be announced acoustically and in some instances marked with fecal piles.\"
Studies show that ovarian activity, pregnancy and parturition appear to be much less seasonal in domestic and feral E. asinus than in wild asses. The short-day anovulatory season in domestic jennies is approximately 165 days, with a high incidence of anovulatory estrus which is brief and frequent. The long-day ovulatory season then is approximately 200 days. The interovulatory interval is approximately 24-25 days. The mean length of ovulatory estrus is about 6 days, with ovulation within the last 1-2 days of estrus. Gestation length is 12 months (McDonnell, 1998).
Nutrition
Equus asinus are grazing herbivores, with large, flat-surfaced teeth adapted for tearing and chewing plant matter. Their primary food is grass, but they also eat other shrubs and desert plants. Like many other grazing animals, they grasp the plant first with their muscular lips, pull it into their mouth, and then tear it off with their teeth. In a study of feral E. asinus in Arizona, they were found to eat 33% forbs and 40% browse (Huggins 2002).
Principal source: Stubbs, C. J. 1999. Feral burro Removal: New Solutions to an Old Problem. Natural Resource Year in Review: publication D-1346.
Department of the Environment and Heritage. 2004. Feral horse (Equus caballus) and feral donkey (Equus asinus). Invasive Species.
Huffman, B. 2004. Equus asinus, African wild ass. An Ultimate Ungulate Fact Sheet.
Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Updates with support from the Overseas Territories Environmental Programme (OTEP) project XOT603, a joint project with the Cayman Islands Government - Department of Environment
Review: Albano Beja Pereira, CIBIO- University of Porto Campus Agrario de Vairao, Portugal
Publication date: 2010-09-15
Recommended citation: Global Invasive Species Database (2024) Species profile: Equus asinus. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=639 on 19-04-2024.
General Impacts
Feral Equus asinus populations in Mojave are having deleterious and potentially irreversible impacts on native flora and fauna. Damage has been documented in plant communities, soils, wildlife, and water quality. Of particular concern is the competition for forage, which is negatively affecting the threatened desert tortoise (see Gopherus agassizii in IUCN Red List of Threatened Species). An adult E. asinus consumes as much as 2,722kg (6,000 pounds) of forage per year, and the herds reproduce at an alarming rate. Reproduction estimates for Mojave National Preserve suggest that the population grows an average of 25% each year (Stubbs, 1999). Heavy grazing on the native vegetation by feral populations of E. asinus allows non-native annuals to displace native perennials, and costs the nation an estimated $5 million per year in forage losses, implying that these species eat forage worth US$100 per animal per year. They also diminish the primary food sources of native bighorn sheep (Ovis canadensis) and seed-eating birds, reducing the abundance of these natives (McNeely (undated); Pimentel et al. 2000).
The Department of the Environment and Heritage (2004) Australia classify feral E. asinus as serious environmental pests. They cause erosion and damage vegetation with their hard hoofs. They damage and foul waterholes, and introduce weeds through seeds carried in their dung, manes and tails. E. asinus may also compete for food and water with native animals. The impact of E. asinus on native grasses, herbs, shrubs and drinkable water is most pronounced during drought. They can quickly degrade areas close to remote waterholes, which during a drought become refuges critical to the survival of many native animals and plants. Without these refuges, native plants and animals may become locally extinct. E. asinus also have an impact on the productivity of farming land.
Results of a study in the high altitude Spiti Valley, Indian Trans-Himalaya, on the competition between seven species of livestock (Equus asinus being one of the seven) and the wild herbivore mountain ungulate bharal (Pseudois nayaur) showed that there is dietry overlap among these herbivore species. The study concluded that this high diet overlap between livestock and bharal, together with density-dependent forage limitation, results in resource competition and a decline in bharal density (Mishra et al. 2004).
Management Info
Physical: The Mojave National Preserve have been provided with funding from the Natural Resource Preservation Program to capture and remove all of its 1,300 remaining burros over a three-year period from 1999 through 2001. Geographic barriers and existing highway fences outside the park are designed to keep other E. asinus out of the preserve (Stubbs 1999). Stubbs (1999) observes that, \"The greatest challenge and potential impediment to a successful E. asinus removal program is placement of the animals once they are captured\".
In Australia, drought has a severe impact on E. asinus. During drought many individuals can die, mainly from starvation, lack of water and eating toxic plants that they usually avoid. They gather round waterholes where they are often culled for humane reasons (Department of the Environment and Heritage 2004). Herds are often mustered and usually some of the younger are turned into pets. Trapping may be less stressful than mustering, but there are animal welfare concerns about the handling of feral E. asinus in traps and during transport to abattoirs.
Biological: Fertility control is a non-lethal approach to feral horse management but it is currently of limited use. Fertility control techniques are difficult to administer to large numbers of feral E. asinus and the treatment would need to be repeated often to be effective. It is not yet known whether such techniques can reduce the environmental damage caused by a population of feral E. asinus in an area of high conservation value.
