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The Bactrian camel (Camelus bactrianus) is a large, even-toed ungulate native to the steppes of Central Asia. Of the two species of camels, it is by far the rarest. The Bactrian camel has two humps on its back, in contrast to the single-humped dromedary camel.  Its population of two million exists mainly in the domesticated form.  Some authorities, notably the International Union for Conservation of Nature (IUCN), use the binomial name Camelus ferus for the wild Bactrian camel and reserve Camelus bactrianus for the domesticated Bactrian camel. Their name comes from the ancient historical region of Bactria.

The domesticated Bactrian camel has served as a pack animal in inner Asia since ancient times. With its tolerance for cold, drought, and high altitudes, it enabled the travel of caravans on the Silk Road.  The wild form has dwindled to a population  estimated at 800 in October 2002 and has been classified as critically endangered on the IUCN Red List of Threatened Species. Database entry includes justification for why this species is critically endangered Its range in the wild is restricted to remote regions of the Gobi and Taklamakan Deserts of Mongolia and China. A small number of wild Bactrian camels still roam the Mangystau Province of southwest Kazakhstan and the Kashmir Valley in India.  Feral herds of Bactrian camels are found in Australia. 

Taxonomy

The Bactrian camel shares the genus Camelus with the dromedary (C. dromedarius) and the wild Bactrian camel (C. ferus). The Bactrian camel belongs to the family Camelidae. The ancient Greek philosopher Aristotle (4th century BC) was the first to describe the species of Camelus. He named two species in his History of Animals: the one-humped Arabian camel and the two-humped Bactrian camel.   The Bactrian camel was given its current binomial name Camelus bactrianus by Swedish zoologist Carl Linnaeus in his 1758 publication Systema Naturae.

In 2007, Peng Cui (of the Chinese Academy of Sciences) and colleagues carried out a phylogenetic study of the evolutionary relationships between the two tribes of Camelidae: Camelini - consisting of the three Camelus species (the study considered the wild Bactrian camel as a subspecies of the Bactrian camel) - and Lamini - consisting of the alpaca (Vicugna pacos), the guanaco (Lama guanicoe), the llama (L. glama) and the vicuña (V. vicugna). The study revealed that the two tribes had diverged 25 million years ago (early Miocene), notably earlier than what had been previously estimated from North American fossils. Speciation began first in Lamini as the alpaca came into existence 10 million years ago (late Pleistocene). Nearly two million years later, the Bactrian camel and the dromedary emerged as two independent species. 

The Bactrian camel and the dromedary often interbreed to produce fertile offspring. Where the ranges of the two species overlap, such as in northern Punjab, Persia and Afghanistan, the phenotypic differences between them tend to decrease as a result of extensive crossbreeding between them. The fertility of their hybrid has given rise to speculation that the Bactrian camel and the dromedary should be merged into a single species with two varieties.  However, a 1994 analysis of the mitochondrial cytochrome b gene revealed that the species display 10.3% divergence in their sequences.

Subspecies

The wild Bactrian camel (Camulus ferus) was first described by Nikolay Przhevalsky in the late 19th century.Zoological opinion nowadays tends to favour the idea that C. bactrianus and C. dromedarius are descendants of two different subspecies of C. ferus (Peters and von den Driesch 1997: 652) and there is no evidence to suggest that the original range of C. ferus included those parts of Central Asia and Iran where some of the earliest Bactrian remains have been found.  In particular, a population of wild Bactrian camel has been discovered to live within a part of the Gashun Gobi region of the Gobi Desert. This population is distinct from domesticated herds both in genetic makeup and in behavior.

As many as three regions in the genetic makeup are distinctly different from domesticated camels, with up to a 3% difference in the base genetic code. However, with so few wild camels, what the natural genetic diversity within a population would have been is not clear.

Another difference is the ability of these wild camels to drink saltwater slush, although whether the camel can extract useful water from it is not yet certain. Domesticated camels are unable to drink such salty water. 

Description

The Bactrian camel is the largest mammal in its native range and rivals the dromedary as the largest living camel. Shoulder height is from 180 to, head-and-body length is 225 -, and the tail length is 35 -. At the top of the humps, the average height is 213 cm. Body mass can range from 300 to, with males often being much larger and heavier than females.   Its long, wooly coat varies in colour from dark brown to sandy beige. A mane and beard of long hair occurs on the neck and throat, with hairs measuring up to 25 cm long. The shaggy winter coat is shed extremely rapidly, with huge sections peeling off at once, appearing as if sloppily shorn off. The two humps on the back are composed of fat (not water as is sometimes thought). The face is typical of a camelid, being long and somewhat triangular, with a split upper lip. The long eyelashes, along with the sealable nostrils, help to keep out dust in the frequent sandstorms which occur in their natural range. The two broad toes on each foot have undivided soles and are able to spread widely as an adaptation to walking on sand. The feet are very tough, as befits an animal of extreme environments.

Natural habitat

These camels are migratory, and their habitat ranges from rocky mountain massifs to flat arid desert, stony plains, and sand dunes. Conditions are extremely harsh – vegetation is sparse, water sources are limited and temperatures are extreme, ranging from as low as −40 °C in winter to 40 °C in summer. The camels’ distribution is linked to the availability of water, with large groups congregating near rivers after rain or at the foot of the mountains, where water can be obtained from springs in the summer months, and in the form of snow during the winter.

Life history

Bactrian camels are exceptionally adept at withstanding wide variations in temperature – ranging from freezing cold to blistering heat. They have a remarkable ability to go without water for months at a time, but when water is available they may drink up to 57 liters at once. When well fed, the humps are plump and erect, but as resources decline, the humps shrink and lean to the side. When moving faster than a walking speed, they pace, by stepping forwards with both legs on the same side (as opposed to trotting, using alternate diagonals as done by most other quadrupeds). Speeds of up to  have been recorded, but they rarely move this fast.  Bactrian camels are also said to be good swimmers. The sense of sight is well developed and the sense of smell is extremely good. The lifespan of Bactrian camels is estimated at up to 50 years, often 20 to 40 in captivity.

Diet 

Bactrian camels are diurnal, sleeping in the open at night and foraging for food during the day. They are primarily herbivorous. They are able to eat plants that are dry, prickly, salty and/or bitter, and can ingest virtually any kind of vegetation. When other nutrient sources are not available, these camels may feed on carcasses, gnawing on bones, skin, or various different kinds of flesh. In more extreme conditions, they may eat any material they find, which has included rope, sandals, and even tents. Their ability to feed on a wide range of foods allows them to live in areas with sparse vegetation. With tough mouths that can withstand sharp objects such as thorns, the digestion process begins. The first time food is swallowed, it is not fully chewed. The partly masticated food (called cud) goes into the stomach and later is brought back up for further chewing.

Bactrian camels belong to a fairly small group of animals that regularly eat snow to provide their water needs. Any animals living above the snowline are obliged to do this, as snow and ice are the only forms of water during winter, and by doing so, their range is greatly enlarged. The latent heat of snow and ice is enormous compared with the heat capacity of water, demanding a large sacrifice in heat energy and forcing animals to eat only small amounts at a time. 

Group organisation 

The population density of wild Bactrian camels is calculated to be five animals per 100 square kilometers. Wild camels generally appear to live in groups of up to 30 individuals, though most groups contain six to 20 individuals. A mature male acts as the leader of the group. Typically, Bactrian camels seen alone are postdispersal young individuals which have just reached sexual maturity.

Reproduction 

Bactrian camels are induced ovulators - they ovulate after insemination of semen into the vagina; the seminal plasma, not the spermatozoa, induces ovulation. Ovulation occurs in 87% of females after insemination: 66% ovulate within 36 h and the rest by 48 h (the same as natural mating). The least amount of semen required to elicit ovulation is about 1.0 ml. 

The mating season occurs in the fall. Males during this time are often quite violent and may bite, spit, or attempt to sit on other male camels. The age of sexual maturity varies, but is usually reached at 3 to 5 years. Gestation lasts around 13 months, with most young being born from March through April. One or occasionally two calves are produced, and the female can give birth to a new calf every other year. Young Bactrian camels are precocial, being able to stand and run shortly after birth, and are fairly large at an average birth weight of 36 kg. They are nursed for about 1.5 years. The young calf stays with its mother for three to five years, until it reaches sexual maturity, and often serves to help raise subsequent generations for those years. Wild camels sometimes breed with domesticated or feral camels, as well.

Threats 

The only extant predators that regularly target wild Bactrian camels are gray wolves, which have been seen to pursue weaker and weather-battered camels as they try to reach oases.  Due to increasingly dry conditions in the species' range, the numbers of cases of wolf predation on wild camels at oases has reportedly increased.  Historically, the Caspian tiger was also known to prey on wild Bactrian camels, but this subspecies is almost certainly extinct. 

History

The Bactrian camel is thought to have been domesticated (independently of the dromedary) sometime before 2500 BCE,  in Northeast Afghanistan, or southwestern Turkestan.  The dromedary camel is believed to have been domesticated between 4000 BCE and 2000 BCE  in Arabia. As pack animals, these ungulates are virtually unsurpassed, able to carry 170 - at a rate of 47 km (30 miles) per day, or 4 km/h (2 mph) over a period of four days.

Bactrian camels have been the focus of artwork throughout history. For example, western foreigners from the Tarim Basin and elsewhere were depicted in numerous ceramic figurines of the Chinese Tang dynasty (618–907).

Evolutionary history

As of the 1980s, a complete range of fossils suggests the first camelids appeared in North America about 30 million years ago, had relatively small body masses, and were adapted to warm climates. 
By the early Pleistocene (about 2 million years ago), they had already evolved into a form similar to the current Bactrian camel, and many individuals permanently migrated to the opposite end of the Bering Strait in an abrupt fashion, probably as a response to the advancing ice age. The remaining related types of American camelids are now only in South America.

Documentaries 

* The Story of the Weeping Camel is a 2003 Mongolian documentary/story about a family of nomadic shepherds trying to get a white calf accepted by his mother, which rejected him after a difficult birth.
* Planet Earth: "Deserts" shows footage of wild camels from a two-month trek in the Gobi desert. It includes a "diary" section, explaining the difficulties in obtaining the footage.

Conservation 

The wild Bactrian camel was identified as one of the top ten "focal species" in 2007 by the Evolutionarily Distinct and Globally Endangered (EDGE) project, which prioritises unique and threatened species for conservation.  Fewer than a thousand (around 600 individuals) are thought to survive in the wild and the population is decreasing. The immediate threats faced by the species are all human related. Firstly, habitat loss has been high due to development for mining and industrial complexes. Due to increasing human populations, wild camels are forced to share food and water sources with introduced domestic stock, thus are sometimes shot by farmers. Included in this stock are domesticated Bactrians, which freely mate with wild individuals. This has led to a concern of a loss of genetically distinct wild Bactrian camels.

Facilitated by the Wild Camel Protection Foundation, two wildlife preserves were founded by the governments of Mongolia and China to protect the Gobi desert, the Great Gobi Reserve A in Mongolia in 1982, and the Arjin Shan Lop Nur Nature Reserve in China in 2000.  A small captive-breeding program has also been started, with the ultimate goal of reintroduction.

Gallery

File:Riding Bactrian camel Nubra.jpg|Riding a Bactrian camel in Nubra Valley, India
File:Wild Bactrian camel on road east of Yarkand.jpg|Wild Bactrian camel during a sandstorm east of Yarkand, Taklamakan Desert, Northwest China
File:Temee.jpg|Bactrian camels in Mongolia
File:Camels in Kosh-Agachsky District.jpg|Bactrian camels in the Chuya Steppe, Altai Mountains, Russia A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as "humps" on its back. The two surviving species of camel are the dromedary, or one-humped camel (C. dromedarius), which inhabits the Middle East and the Horn of Africa; and the Bactrian, or two-humped camel (C. bactrianus), which inhabits Central Asia. Both species have been domesticated; they provide milk, meat, hair for textiles or goods such as felted pouches, and are working animals with tasks ranging from human transport to bearing loads.

The term camel is derived via Latin and Greek (camelus and κάμηλος kamēlos respectively) from Hebrew or Phoenician gāmāl.  

"Camel" is also used more broadly to describe any of the six camel-like mammals in the family Camelidae: the two true camels and the four New World camelids: the llama, alpaca, guanaco, and vicuña of South America.

Biology

The average life expectancy of a camel is 40 to 50 years. A full-grown adult camel stands  at the shoulder and  at the hump. Camels can run at up to 65 km/h in short bursts and sustain speeds of up to 40 km/h. Bactrian camels weigh 300 to and dromedaries 300 to.

The male dromedary camel has in its throat an organ called a dulla, a large, inflatable sac he extrudes from his mouth when in rut to assert dominance and attract females. It resembles a long, swollen, pink tongue hanging out of the side of its mouth.  Camels mate by having both male and female sitting on the ground, with the male mounting from behind.  The male usually ejaculates three or four times within a single mating session. Camelids are the only ungulates to mate in a sitting position.

Ecological and behavioral adaptations

Camels do not directly store water in their humps as was once commonly believed. The humps are actually reservoirs of fatty tissue: concentrating body fat in their humps minimizes the insulating effect fat would have if distributed over the rest of their bodies, helping camels survive in hot climates.  When this tissue is metabolized, it yields more than one gram of water for every gram of fat processed. This fat metabolization, while releasing energy, causes water to evaporate from the lungs during respiration (as oxygen is required for the metabolic process): overall, there is a net decrease in water.

Camels have a series of physiological adaptations that allow them to withstand long periods of time without any external source of water. Unlike other mammals, their red blood cells are oval rather than circular in shape. This facilitates the flow of red blood cells during dehydration  and makes them better at withstanding high osmotic variation without rupturing when drinking large amounts of water: a 600 kg camel can drink 200 L of water in three minutes. 

Camels are able to withstand changes in body temperature and water consumption that would kill most other animals. Their temperature ranges from 34 °C at dawn and steadily increases to 40 °C by sunset, before they cool off at night again. Maintaining the brain temperature within certain limits is critical for animals; to assist this, camels have a rete mirabile, a complex of arteries and veins lying very close to each other which utilizes countercurrent blood flow to cool blood flowing to the brain.  Camels rarely sweat, even when ambient temperatures reach 49 °C. Any sweat that does occur evaporates at the skin level rather than at the surface of their coat; the heat of vaporization therefore comes from body heat rather than ambient heat. Camels can withstand losing 25% of their body weight to sweating, whereas most other mammals can withstand only about 12–14% dehydration before cardiac failure results from circulatory disturbance.

When the camel exhales, water vapor becomes trapped in their nostrils and is reabsorbed into the body as a means to conserve water.  Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies' hydrated state without the need for drinking.

The camels' thick coats insulate them from the intense heat radiated from desert sand; a shorn camel must sweat 50% more to avoid overheating.  During the summer the coat becomes lighter in color, reflecting light as well as helping avoid sunburn. The camel's long legs help by keeping its body farther from the ground, which can heat up to 70 °C.  Dromedaries have a pad of thick tissue over the sternum called the pedestal.  When the animal lies down in a sternal recumbent position, the pedestal raises the body from the hot surface and allows cooling air to pass under the body.

Camels' mouths have a thick leathery lining, allowing them to chew thorny desert plants. Long eyelashes and ear hairs, together with nostrils that can close, form a barrier against sand. If sand gets lodged in their eyes, they can dislodge it using their transparent third eyelid. The camels' gait and widened feet help them move without sinking into the sand.

The kidneys and intestines of a camel are very efficient at reabsorbing water. Camel urine comes out as a thick syrup, and camel feces are so dry that they do not require drying when the Bedouins use them to fuel fires.

Camels' immune system differs from those of other mammals. Normally, the Y-shaped antibody molecules consist of two heavy (or long) chains along the length of the Y, and two light (or short) chains at each tip of the Y. Camels, in addition to these, also have antibodies made of only two heavy chains, a trait that makes them smaller and more durable. These "heavy-chain-only" antibodies, discovered in 1993, are thought to have developed 50 million years ago, after camelids split from ruminants and pigs. 

Genetics

The karyotypes of different camelid species have been studied earlier by many groups,       but no agreement on chromosome nomenclature of camelids has been reached. A 2007 study flow sorted camel chromosomes, building on the fact that camels have 37 pairs of chromosomes (2n=74), and found that the karyotime consisted of one metacentric, three submetacentric, and 32 acrocentric autosomes. The Y is a small metacentric chromosome, while the X is a large metacentric chromosome. 

The hybrid camel, a hybrid between Bactrian and dromedary camels, has one hump, though it has an indentation 4 – deep that divides the front from the back. The hybrid is  at the shoulder and  tall at the hump. It weighs an average of 650 kg and can carry around 400 to, which is more than either the dromedary or Bactrian can.

According to molecular data, the New World and Old World camelids diverged 11 million years ago.  In spite of this, these species can still hybridize and produce fertile offspring.  The cama is a camel–llama hybrid bred by scientists who wanted to see how closely related the parent species were. Scientists collected semen from a camel via an artificial vagina and inseminated a llama after stimulating ovulation with gonadotrophin injections. The cama has ears halfway between the length of camel and llama ears, no hump, longer legs than the llama, and partially cloven hooves. According to cama breeder Lulu Skidmore, cama have "the fleece of the llamas" and "the strength and patience of the camel". Like the mule, camas are sterile, despite both parents having the same number of chromosomes.

Evolution

The earliest known camel, called Protylopus, lived in North America 40 to 50 million years ago (during the Eocene). It was about the size of a rabbit and lived in the open woodlands of what is now South Dakota. By 35 million years ago, the Poebrotherium was the size of a goat and had many more traits similar to camels and llamas. The hoofed Stenomylus, which walked on the tips of its toes, also existed around this time, and the long-necked Aepycamelus evolved in the Miocene.

The direct ancestor of all modern camels, Procamelus, existed in the upper Miocene and lower Pliocene. Around 3–5 million years ago, the North American Camelidae spread to South America via the Isthmus of Panama, where they gave rise to guanacos and related animals, and to Asia via the Bering land bridge. Surprising finds of fossil Paracamelus on Ellesmere Island beginning in 2006 in the high Canadian Arctic indicate the dromedary is descended from a larger, boreal browser whose hump may have evolved as an adaptation in a cold climate.   This creature is estimated to have stood around nine feet tall. 

The last camel native to North America was Camelops hesternus, which vanished along with horses, short-faced bears, mammoths and mastodons, ground sloths, sabertooth cats, and many other megafauna, coinciding with the migration of humans from Asia.

Domestication

Most camels surviving today are domesticated. Along with many other megafauna in North America, the original wild camels were wiped out during the spread of Native Americans from Asia into North America, 12,000 to 10,000 years ago. The only wild camels left are the Bactrian camels of the Gobi Desert.

Like the horse, before their extinction in their native land, camels spread across the Bering land bridge, moving the opposite direction from the Asian immigration to America, to survive in the Old World and eventually be domesticated and spread globally by humans.

Dromedaries may have first been domesticated by humans in Somalia and southern Arabia, around 3,000 BC, the Bactrian in central Asia  around 2,500 BC,    as at Shar-i Sokhta (also known as the Burnt City), Iran. 

Discussions concerning camel domestication in Mesopotamia are often related to mentions of camels in the Hebrew Bible. The International Standard Bible Encyclopedia: E-J for instance mentions that "In accord with patriarchal traditions, cylinder seals from Middle Bronze Age Mesopotamia showed riders seated upon camels."  

Martin Heide's 2010 work on the domestication of the camel tentatively concludes that the bactrian camel was domesticated by at least the middle of the third millennium somewhere east of the Zagros Mountains, then moving into Mesopotamia, and suggests that mentions of camels "in the patriarchal narratives may refer, at least in some places, to the Bactrian camel." while noting that the camel is not mentioned in relationship to Canaan. 

Recent excavations in the Timna Valley by Lidar Sapir-Hen and Erez Ben-Yosef discovered what may be the earliest domestic camel bones found in Israel or even outside the Arabian peninsula, dating to around 930 BCE. This garnered considerable media coverage as it was described as evidence that the stories of Abraham, Joseph, Jacob and Esau were written after this time. 

The existence of camels in Mesopotamia but not in Israel is not a new idea. According to an article in Time Magazine, the historian Richard Bulliet wrote in his 1975 book "The Camel and the Wheel" that "the occasional mention of camels in patriarchal narratives does not mean that the domestic camels were common in the Holy Land at that period." The archaeologist William F. Albright writing even earlier saw camels in the Bible as an anachronism. 
The official report by Sapir-Hen and Ben-Joseph notes that "The introduction of the dromedary camel (Camelus dromedarius) as a pack animal to the southern Levant signifies a crucial juncture in the history of the region; it substantially facilitated trade across the vast deserts of Arabia, promoting both economic and social change (e.g., Kohler 1984; Borowski 1998: 112-116; Jasmin 2005). This, together with the depiction of camels in the Patriarchal narrative, has generated extensive discussion regarding the date of the earliest domestic camel in the southern Levant (and beyond) (e.g., Albright 1949: 207; Epstein 1971: 558-584; Bulliet 1975; Zarins 1989; Köhler-Rollefson 1993; Uerpmann and Uerpmann 2002; Jasmin 2005; 2006; Heide 2010; Rosen and Saidel 2010; Grigson 2012). Most scholars today agree that the dromedary was exploited as a pack animal sometime in the early Iron Age (not before the 12th century BCE)" and concludes that "Current data from copper smelting sites of the Aravah Valley enable us to pinpoint the introduction of domestic camels to the southern Levant more precisely based on stratigraphic contexts associated with an extensive suite of radiocarbon dates. The data indicate that this event occurred not earlier than the last third of the 10th century BCE and most probably during this time. The coincidence of this event with a major reorganization of the copper industry of the region—attributed to the results of the campaign of Pharaoh Shoshenq I—raises the possibility that the two were connected, and that camels were introduced as part of the efforts to improve efficiency by facilitating trade."

Military uses

By at least 1200 BC, the first camel saddles had appeared, and Bactrian camels could be ridden. The first saddle was positioned to the back of the camel, and control of the Bactrian camel was exercised by means of a stick. However, between 500–100 BC, Bactrian camels attained military use. New saddles, which were inflexible and bent, were put over the humps and divided the rider's weight over the animal. In the seventh century BC, the military Arabian saddle appeared, which improved the saddle design again slightly. 

Camel cavalries have been used in wars throughout Africa, the Middle East, and into modern-day Border Security Force of India (though as of July 2012, the BSF has planned the replacement of camels with ATVs). The first use of camel cavalries was in the Battle of Qarqar in 853 BC. Armies have also used camels as freight animals instead of horses and mules.

In the East Roman Empire, the Romans used auxiliary forces known as dromedarii, whom they recruited in desert provinces. The camels were used mostly in combat because of their ability to scare off horses at close ranges (horses are afraid of the camels' scent), a quality famously employed by the Achaemenid Persians when fighting Lydia in the Battle of Thymbra.

19th and 20th centuries

* The United States Army established the U.S. Camel Corps, which was stationed in California in the late 19th century. One may still see stables at the Benicia Arsenal in Benicia, California, where they nowadays serve as the Benicia Historical Museum. Though the experimental use of camels was seen as a success (John B. Floyd, Secretary of War in 1858, recommended that funds be allocated towards obtaining a thousand more camels), the outbreak of the American Civil War saw the end of the Camel Corps: Texas became part of the Confederacy, and most of the camels were left to wander away into the desert.
* France created a méhariste camel corps in 1912 as part of the Armée d'Afrique in the Sahara in order to exercise greater control over the camel-riding Tuareg and Arab insurgents, as previous efforts to defeat them on foot had failed. The camel-mounted units remained in service until the end of French rule over Algeria in 1962.
* In 1916, the British created the Imperial Camel Corps. It was originally used to fight the Senussi, but was later used in the Sinai and Palestine Campaign in World War I. The Imperial Camel Corps comprised infantrymen mounted on camels for movement across desert, though they dismounted at battle sites and fought on foot. After July 1918, the Corps began to become run down, receiving no new reinforcements, and was formally disbanded in 1919.
* In World War I, the British Army also created the Egyptian Camel Transport Corps, which consisted of a group of Egyptian camel drivers and their camels. The Corps supported British war operations in Sinai, Palestine, and Syria by transporting supplies to the troops.
* The Somaliland Camel Corps was created by colonial authorities in British Somaliland in 1912; it was disbanded in 1944.
* Bactrian camels were used by Romanian forces during World War II in the Caucasian region.
* The Bikaner Camel Corps of British India fought alongside the British Indian Army in World Wars I and II.
* The Tropas Nómadas (Nomad Troops) were an auxiliary regiment of Sahrawi tribesmen serving in the colonial army in Spanish Sahara (today Western Sahara). Operational from the 1930s until the end of the Spanish presence in the territory in 1975, the Tropas Nómadas were equipped with small arms and led by Spanish officers. The unit guarded outposts and sometimes conducted patrols on camelback.

Food uses

Dairy

Camel milk is a staple food of desert nomad tribes and is sometimes considered a meal in and of itself; a nomad can live on only camel milk for almost a month. Camel milk is rich in vitamins, minerals, proteins, and immunoglobulins; compared to cow's milk, it is lower in fat and lactose, and higher in potassium, iron, and vitamin C. Bedouins believe the curative powers of camel milk are enhanced if the camel's diet consists of certain desert plants. Camel milk can readily be made into a drinkable yogurt, as well as butter or cheese, though the yields for cheese tend to be low.

Camel milk cannot be made into butter by the traditional churning method. It can be made if it is soured first, churned, and a clarifying agent is then added. Until recently, camel milk could not be made into camel cheese because rennet was unable to coagulate the milk proteins to allow the collection of curds. Developing less wasteful uses of the milk, the FAO commissioned Professor J.P. Ramet of the École Nationale Supérieure d'Agronomie et des Industries Alimentaires, who was able to produce curdling by the addition of calcium phosphate and vegetable rennet. The cheese produced from this process has low levels of cholesterol and is easy to digest, even for the lactose intolerant. The sale of camel cheese is limited owing to the small output of the few dairies producing camel cheese and the absence of camel cheese in local (West African) markets. Cheese imports from countries that traditionally breed camels are difficult to obtain due to restrictions on dairy imports from these regions.

Additionally, camel milk has been made into ice cream in a Netherlands camel farm. 

Meat

A camel carcass can provide a substantial amount of meat. The male dromedary carcass can weigh 300 –, while the carcass of a male Bactrian can weigh up to 650 kg. The carcass of a female dromedary weighs less than the male, ranging between 250 and. The brisket, ribs and loin are among the preferred parts, and the hump is considered a delicacy. The hump contains "white and sickly fat", which can be used to make the khli (preserved meat) of mutton, beef, or camel. Camel meat is reported to taste like coarse beef, but older camels can prove to be very tough, although camel meat becomes more tender the more it is cooked. The Abu Dhabi Officers' Club serves a camel burger mixed with beef or lamb fat in order to improve the texture and taste. In Karachi, Pakistan, some restaurants prepare nihari from camel meat. In Syria and Egypt, there are specialist camel butchers. 

Camel meat has been eaten for centuries. It has been recorded by ancient Greek writers as an available dish at banquets in ancient Persia, usually roasted whole. The ancient Roman emperor Heliogabalus enjoyed camel's heel. Camel meat is still eaten in certain regions, including Eritrea, Somalia, Djibouti, Saudi Arabia, Egypt, Syria, Libya, Sudan, Ethiopia, Kazakhstan, and other arid regions where alternative forms of protein may be limited or where camel meat has had a long cultural history. Camel blood is also consumable, as is the case among pastoralists in northern Kenya, where camel blood is drunk with milk and acts as a key source of iron, vitamin D, salts and minerals. Camel meat is also occasionally found in Australian cuisine: for example, a camel lasagna is available in Alice Springs.

A 2005 report issued jointly by the Saudi Ministry of Health and the United States Centers for Disease Control and Prevention details cases of human bubonic plague resulting from the ingestion of raw camel liver. 

Religion

Islam

Camel meat is halal for Muslims. However, according to some Islamic schools of thought, a state of impurity is brought on by the consumption of it. Consequently, these schools hold that Muslims must perform wudhu (ablution) before the next time they pray after eating camel meat. 

Also, some Islamic schools of thought consider it haraam for a Muslim to perform salat in places where camels lie, as it is said to be a dwelling place of shaytan.

According to Suni ahadith collected by Bukhari and Muslim, Muhammad ordered a certain group of people to drink camel milk and urine as a medicine.       However, according to Abū Ḥanīfa, the drinking of camel urine, while not forbidden (ḥaram), is disliked (makrūh) in Islam. 

Camel urine is sold as traditional medicine in shops in Saudi Arabia.       The Sunni scholar Muhammad Al-Munajjid's IslamQA.info recommends camel urine as beneficial to curing certain diseases and to human health and cited Ahadith and scientific studies as justification.     King Abdulaziz University researcher Dr. Faten Abdel-Rajman Khorshid has claimed that cancer and other diseases could be treated with camel urine as recommended by the Prophet.       It is believed to combat cancer by King Abdulaziz University staff and serves as medicine and shampoo.  The United Arab Emirates "Arab Science and Technology Foundation" reported that cancer could be treated with camel urine.   Camel urine was also prescribed as a treatment by Zaghloul El-Naggar, a religious scholar.   Camel urine is the only urine which is permitted to be drunk according to the Hanbali madhhab of Sunni Islam.  The World Health Organization said that camel urine consumption may be a factor in the spread of the MERS virus in Saudi Arabia.         The Gulf Times writer Ahmad al-Sayyed wrote that various afflictions are dealt with camel urine by people.  Camel urine was used to clean hair by Bedouin.  Dandruff, scalp ailments, hair, sores, and wounds were recommended to be treated with camel urine by Ibn Sina.  Arab American University Professor of Cell Biology and Immunology Bashar Saad (PhD) along with Omar Said (PhD) wrote that medicinal use of camel urine is approved of and promoted by Islam since it was recommended by the prophet.  A test on mice found that cytotoxic effects similar to cyclophosphamide were induced on bone marrow by camel urine.   Besides for consumption as a medicinal drink, camel urine is believed to help treat hair.   Bites from insects were warded off with camel urine, which also served as a shampoo.  Camel urine is also used to help treat asthma, infections, treat hair, sores, hair growth and boost libido.  

Several Sunni Ahadith mention camel urine:     

Some Shia criticized Wahhabis for camel urine treatment.    Shia scholars also recommend the medicinal use of camel urine.   Shia Hadith on Imam Ja'far al-Sadiq reported that shortness of breath (asthma) was treated with camel urine.    Shia Marja Ayatollah Sistani said that for medicinal purposes only, sheep, cow, and camel urine can be drunk. 

Judaism

According to Jewish tradition, camel meat and milk are not kosher. Camels possess only one of the two kosher criteria; although they chew their cud, they do not possess cloven hooves: 

Distribution and numbers

There are around 14 million camels alive , with 90% being dromedaries. Dromedaries alive today are domesticated animals (mostly living in the Horn of Africa, the Sahel, Maghreb, Middle East and South Asia). The Horn region alone has the largest concentration of camels in the world,  where the dromedaries constitute an important part of local nomadic life. They provide nomadic people in Somalia (which has the largest camel herd in the world) and Ethiopia with milk, food, and transportation. [http://www.mbali.info/doc265.htm Plain text version.]

The Bactrian camel is, , reduced to an estimated 1.4 million animals, most of which are domesticated. The only truly wild Bactrian camels, of which there are less than one thousand, are thought to inhabit the Gobi Desert in China and Mongolia.

The largest population of feral camels is in Australia. There are around 700,000 feral dromedary camels in central parts of Australia, descended from those introduced as a method of transport in the 19th and early 20th centuries.  This population is growing about 8% per year.  Representatives of the Australian government have culled more than 100,000 of the animals in part because the camels use too much of the limited resources needed by sheep farmers. 

A small population of introduced camels, dromedaries and Bactrians, wandered through Southwest United States after having been imported in the 1800s as part of the U.S. Camel Corps experiment. When the project ended, they were used as draft animals in mines and escaped or were released. Twenty-five U.S. camels were bought and imported to Canada during the Cariboo Gold Rush. The dromedary ( or), also called the Arabian camel (Camelus dromedarius), is a large, even-toed ungulate with one hump on its back. It is one of the three species of camel that was given its current binomial name by Carl Linnaeus in 1758. The dromedary is the largest camel after the Bactrian camel; adult males stand  at the shoulder, while females are  tall. Males  typically weigh between 400 and, and females weigh between 300 and. The species' distinctive features include its long,curved neck, narrow chest, a single hump (compared with two on the Bactrian camel), and long hairs on the throat, shoulders and hump. The coat is generally a shade of brown. The hump, 20 cm tall or more, is made of fat bound together by fibrous tissue.

Dromedaries are mainly active during daylight hours. They form herds of about 20 individuals, which are led by a dominant male. This camel feeds on foliage and desert vegetation; several adaptations, such as the ability to tolerate greater than 30% of the water content of the body, allow it to thrive in its desert habitat. Mating occurs annually and peaks in the rainy season; females bear a single calf after a gestation of 15 months.

The dromedary has not occurred naturally in the wild for nearly 2,000 years. It was probably first domesticated in Somalia or the Arabian Peninsula about 4,000 years ago. In the wild, the dromedary inhabited arid regions, including the Sahara Desert. The domesticated dromedary is generally found in the semi-arid to arid regions of the Old World, mainly in Africa, and a significant feral population occurs in Australia, and were also recently introduced to North America, more specifically, Nevada in the United States. Products of the dromedary, including its meat and milk, support several north Arabian tribes; it is also commonly used for riding and as a beast of burden.

Etymology

The common name "dromedary" comes from the Old French dromedaire or the Late Latin dromedarius. These originated from the Greek word dromas, δρομάς (ο, η) (GEN (γενική) dromados, δρομάδος), meaning "running" or "runner",  used in Greek in the combination  (dromas kamelos), literally "running camel", to refer to the dromedary.  The first recorded use in English of the name "dromedary" occurred in the 14th century.  The dromedary possibly originated in Arabia and is therefore sometimes referred to as the Arabian camel. The word "camel" generally refers either to the dromedary or the congeneric Bactrian; it may have been derived from the Latin word camelus, the Greek kamēlos,  or an old Semitic language such as the Hebrew gāmāl or the Arabic ǧamal. 

Taxonomy and classification

The dromedary shares the genus Camelus with the Bactrian camel (C. bactrianus) and the wild Bactrian camel (C. ferus, sometimes considered a subspecies of the Bactrian camel). The dromedary belongs to the family Camelidae. The ancient Greek philosopher Aristotle (4th century BC) was the first to describe the species of Camelus. He named two species in his History of Animals; the one-humped Arabian camel and the two-humped Bactrian camel.   The dromedary was given its current binomial name Camelus dromedarius by Swedish zoologist Carl Linnaeus in his 1758 publication Systema Naturae. In 1927, British veterinarian Arnold Leese classified dromedaries by their basic habitats; the hill camels are small, muscular animals and efficient beasts of burden; the larger plains camels could be further divided into the desert type that can bear light burdens and are apt for riding, and the riverine type – slow animals that can bear heavy burdens; and those intermediate between these two types. 

In 2007, Peng Cui of the Chinese Academy of Sciences and colleagues carried out a phylogenetic study of the evolutionary relationships between the two tribes of Camelidae; Camelini – consisting of the three Camelus species (the study considered the wild Bactrian camel as a subspecies of the Bactrian camel) – and Lamini, which consists of the alpaca (Vicugna pacos), the guanaco (Lama guanicoe), the llama (L. glama) and the vicuña (V. vicugna). The study showed the two tribes had diverged 25 million years ago (early Miocene), earlier than previously estimated from North American fossils. Speciation began first in Lamini as the alpaca came into existence 10 million years ago (late Pleistocene). Nearly two million years later, the dromedary and the Bactrian camel emerged as two independent species. 

The dromedary and the Bactrian camel often interbreed to produce fertile offspring. Where the ranges of the species overlap, such as in northern Punjab, Persia and Afghanistan, the phenotypic differences between them tend to decrease as a result of extensive crossbreeding. The fertility of their hybrid has given rise to speculation that the dromedary and the Bactrian camel should be merged into a single species with two varieties. However, a 1994 analysis of the mitochondrial cytochrome b gene showed the species display 10.3% divergence in their sequences.

Genetics and hybrids

The dromedary has 74 diploid chromosomes, the same as other camelids. The autosomes consist of five pairs of small to medium-sized metacentrics and submetacentrics. The X chromosome is the largest in the metacentric and submetacentric group. There are 31 pairs of acrocentrics. The dromedary's karyotype is similar to that of the Bactrian camel.

Camel hybridisation began in the first millennium BC. For about a thousand years, Bactrian camels and dromedaries have been successfully bred in regions where they are sympatric to form hybrids with either a long, slightly lopsided hump or two humps – one small and one large. These hybrids are larger and stronger than their parents – they can bear greater loads. A cross between a first generation female hybrid and a male Bactrian camel can also produce a hybrid. Hybrids from other combinations tend to be bad-tempered or runts.

Evolution

The extinct Protylopus, which occurred in North America during the upper Eocene, is the oldest and the smallest-known camel.  During the transition from Pliocene to Pleistocene, several mammals faced extinction. This period marked the successful radiation of the Camelus species, which migrated over the Bering Strait and dispersed widely into Asia, eastern Europe and Africa. By the Pleistocene, ancestors of the dromedary occurred in the Middle East and northern Africa.

The modern dromedary probably evolved in the hotter, arid regions of western Asia from the Bactrian camel, which in turn was closely related to the earliest Old World camels. This hypothesis is supported by the fact that the dromedary foetus has two humps, while in the adult male an anterior vestigial hump is present. A jawbone of a dromedary that dated from 8,200 BC was found in Saudi Arabia on the southern coast of the Red Sea.

In 1975, Richard Bulliet of Columbia University wrote that the dromedary exists in large numbers in areas from which the Bactrian camel has disappeared; the converse is also true to a great extent. He said this substitution could have taken place because of the heavy dependence on the milk, meat and wool of the dromedary by Syrian and Arabian nomads, while the Asiatic people domesticated the Bactrian camel but did not have to depend upon its products.

Characteristics

The dromedary is the largest camel after the Bactrian camel. Adult males range in height between  at the shoulder; females range between . Males typically weigh between 400 and; females range between 300 and. The distinctive features are its long, curved neck, narrow chest and single hump (the Bactrian camel has two), thick, double-layered eyelashes and bushy eyebrows.  They have sharp vision and a good sense of smell. The male has a soft palate (dulaa in Arabic) nearly 18 cm long, which it inflates to produce a deep pink sac. The palate, which is often mistaken for the tongue, dangles from one side of the mouth and is used to attract females during the mating season.

The coat is generally brown but can range from black to nearly white. Leese reported piebald dromedaries in Kordofan and Darfur in Sudan. The hair is long and concentrated on the throat, shoulders and the hump. The large eyes are protected by prominent supraorbital ridges; the ears are small and rounded. The hump is at least 20 cm high. The dromedary has long, powerful legs with two toes on each foot. The feet resemble flat, leathery pads. Like the giraffe, dromedaries moves both legs on one side of the body at the same time. 

Compared with the Bactrian camel, the dromedary has a lighter build, longer limbs, shorter hairs, a harder palate and an insigificant or absent ethmoidal fissure. Unlike the camelids of the genus Lama, the dromedary has a hump, and in comparison has a longer tail, smaller ears, squarer feet and a greater height at the shoulder. The dromedary has four teats instead of the two in the Lama species.

Anatomy

The cranium of the dromedary consists of a postorbital bar, a tympanic bulla filled with spongiosa, a well-defined sagittal crest, a long facial part and an indented nasal bone. Typically, there are eight sternal and four non-sternal pairs of ribs. The spinal cord is nearly 214 cm long; it terminates in the second and third sacral vertebra. The fibula is reduced to a malleolar bone. The dromedary is a digitigrade animal; it walks on its toes, which are known as digits. It lacks the second and fifth digits. The front feet are 19 cm wide and 18 cm long; they are larger than the hind feet, which measure 17 cm wide and 16 cm long.

The dromedary has 22 milk teeth, which are eventually replaced by 34 permanent teeth. The dental formula for permanent dentition is , and  for milk dentition. In the juvenile,  the lower first molars develop by 12 to 15 months and the permanent lower incisors appear at 4.5 to 6.5 years of age. All teeth are in use by 8 years. The lenses of the eyes contain crystallin, which constitutes 8 to 13% of the protein present there.

The skin is black; the epidermis is  thick and the dermis is  thick. The hump is composed of fat bound together by fibrous tissue. There are no glands on the face; males have glands that appear to be modified apocrine sweat glands that secrete pungent, coffee-coloured fluid during the rut, located on either side of the neck midline. The glands generally grow heavier during the rut, and range from 20 to. Each cover hair is associated with an arrector pilli muscle, a hair follicle, a ring of sebaceous glands and a sweat gland. Females have cone-shaped, four-chambered mammary glands that are  long with a base diameter of . These glands can produce milk with up to 90% water content even if the mother is at risk of dehydration.

The heart weighs around 5 kg; it has two ventricles with the tip curving to the left. The pulse rate is 50 beats per minute. The dromedary is the only mammal with oval red blood corpuscles. The pH of the blood varies from 7.1 to 7.6 (slightly alkaline). The individual's state of hydration and sex, and the time of year can influence blood values. The lungs lack lobes. A dehydrated camel has a lower breathing rate. Each kidney has a capacity of 858 cm3, and can produce urine with high chloride concentrations. Like the horse, the dromedary has no gall bladder. The grayish violet, crescent-like spleen weighs less than 500 g. The triangular, four-chambered liver weighs ; its dimensions are: 60 *.

Reproductive system

The ovaries are reddish, circular and flattened. They are enclosed in a conical bursa and have the dimensions  4 * during anestrus. The oviducts are 25 - long. The uterus is bicornuate. The vagina is 3 - long and has well-developed Bartholin's glands. The vulva is 3 - deep and has a small clitoris. The placenta is diffuse and epitheliochorial, with a crescent-like chorion.

The penis is covered by a triangular penile sheath that opens backwards; it is about 60 cm long. The scrotum is located high in the perineum with the testicles in separate sacs.  Testicles are 7 - long,  deep and 5 cm wide. The right testicle is often smaller than the left. The typical mass of either testicle is less than 140 g; during the rut the mass increases from 165 to. The Cowper's gland is white, almond-shaped and lacks seminal vesicles; the prostate gland is dark yellow, disc-shaped and divided into two lobes.

Health and diseases

The dromedary generally suffers from fewer diseases than  other domestic livestock such as goats and cattle. Temperature fluctuations occur throughout the day in a healthy dromedary – the temperature falls to its minimum at dawn, rises until sunset and falls during the night. Nervous camels may vomit if they are carelessly handled; this does not always indicate a disorder. Rutting males may develop nausea.

The dromedary is prone to trypanosomiasis, a disease caused by a parasite transmitted by the tsetse fly. The main symptoms are recurring fever, anaemia and weakness; the disease is typically fatal for the camel. Brucellosis is another prominent malady. In an observational study, the seroprevalence of this disease was generally low (2 to 5%) in nomadic or moderately free dromedaries, but it was higher (8 to 15%) in denser populations. Brucellosis is caused by different biotypes of Brucella abortus and B. melitensis. Other internal parasites include Fasciola gigantica (trematode), two types of  cestode (tapeworm) and various nematodes (roundworms). Among external parasites, Sarcoptes species cause sarcoptic mange. In a 2000 study in Jordan, 83% of the 32 camels studied tested positive for sarcoptic mange. In another study, dromedaries were found to have natural antibodies against the rinderpest and ovine rinderpest viruses. 

In 2013, a seroepidemiological study (a study investigating the patterns, causes and effects of a disease on a specific population on the basis of serologic tests) in Egypt was the first to show the dromedary might be a host for the Middle East respiratory syndrome coronavirus (MERS-CoV). A 2013–14 study of dromedaries in Saudi Arabia concluded the unusual genetic stability of MERS-CoV coupled with its high seroprevalence in the dromedary makes this camel a highly probable host for the virus. The full genome sequence of MERS-CoV from dromedaries in this study showed a 99.9% match to the genomes of human clade B MERS-CoV. Another study in Saudi Arabia showed the presence of MERS-CoV in 90% of the evaluated dromedaries and suggested that camels could be the animal source of MERS-CoV.

Fleas and ticks are common causes of physical irritation. In a study in Egypt, a species of Hyalomma was dominant in dromedaries, comprising 95.6% of the adult ticks isolated from the camels. In Israel, the number of ticks per camel ranged from 20 to 105. Nine camels in the date palm plantations in Arava Valley were injected with ivermectin, which is not effective against Hyalomma tick infestations.  Larvae of the camel nasal fly Cephalopsis titillator can cause possibly fatal brain compression and nervous disorders. Illnesses that can affect dromedary productivity are pyogenic diseases and wound infections caused by Corynebacterium and Streptococcus, pulmonary disorders caused by Pasteurella such as hemorrhagic septicemia and Rickettsia species, camelpox, anthrax, and cutaneous necrosis caused by Streptothrix and deficiency of salt in the diet.

Ecology

The dromedary is diurnal (active mainly during daylight); free-ranging herds feed and roam throughout the day, though they rest during the hottest hours around noon. The night is mainly spent resting. Dromedaries form cohesive groups of about 20 individuals, which consist of several females led by a dominant male. Females may also lead in turns. Some males either form bachelor groups or roam alone. Herds may congregate to form associations of hundreds of camels during migrations at the time of natural disasters. The males of the herd prevent female members from interacting with bachelor males by standing or walking between them and somtimes driving the bachelor males away. In Australia, short-term home ranges of feral dromedaries cover 50 to; annual home ranges can spread over several thousand square kilometres.

Special behavioural features of the dromedary include snapping at others without biting them and showing displeasure by stamping their feet. They are generally non-aggressive, with the exception of rutting males. They appear to remember their homes; females in particular remember the places they first gave birth or suckled their offspring. Males become aggressive in the mating season, and sometimes wrestle. A 1980 study showed androgen levels in males influences their behaviour. Between January and April when these levels are high during the rut, they become difficult to manage, blow out the palate from the mouth, vocalise and throw urine over their backs. Camels scratch parts of their bodies with their legs or with their lower incisors. They may also rub against tree bark and roll in sand.

Free-ranging dromedaries face large predators typical of their regional distribution, which includes wolves, lions and tigers.

Diet

The dromedary's diet consists mostly of foliage, dry grasses and desert vegetation – mostly thorny plants. A study said the typical diet of the dromedary is dwarf shrubs (47.5%), trees (29.9%), grasses (11.2%), other herbs (0.2%) and vines (11%). The dromedary is primarily a browser; forbs and shrubs comprise 70% of its diet in summer and 90% of its diet in winter. The dromedary may also graze on or suck in tall, young, succulent grasses.

In the Sahara, 332 plant species have been recorded as food plants of the dromedary. These include Aristida pungens, Acacia tortilis, Panicum turgidum, Launaea arborescens and Balanites aegyptiaca. The dromedary eats Acacia, Atriplex and Salsola when they are available. Feral dromedaries in Australia prefer Trichodesma zeylanicum and Euphorbia tannensis. In India, dromedaries are fed with forage plants such as Vigna aconitifolia, V. mungo, Cyamopsis tetragonolaba, Melilotus parviflora, Eruca sativa, Trifolium species and Brassica campestris. Dromedaries keep their mouths open while chewing thorny food. They use their lips to grasp the food and chew each bite 40 to 50 times. Its long eyelashes, eyebrows, lockable nostrils, caudal opening of the prepuce and a relatively small vulva help the camel avoid injuries, especially while feeding. They graze for 8–12 hours per day and ruminate for an equal amount of time.

Adaptations

The dromedary is specially adapted to its desert habitat; these adaptations are aimed at conserving water and regulating body temperature. The bushy eyebrows and the double row of eyelashes prevent sand and dust from entering the eyes during strong windstorms,and shield them from the sun's glare. The dromedary is able to close its nostrils voluntarily; this assists in water conservation. The dromedary can conserve water by reducing perspiration by fluctuating the body temperature throughout the day from 31 to. The kidneys are specialised to minimise water loss through excretion. Groups of camels avoid excess heat from the environment by pressing against each other. The dromedary can tolerate greater than 30% water loss, which is generally impossible for other mammals. In temperatures between 30 and, it needs water every 10 to 15 days. In the hottest temperatures the dromedary takes water every four to seven days. This camel has a quick rate of rehydration and can drink at 10 - per minute. The dromedary has a rete mirabile, a complex of arteries and veins lying very close to each other which uses countercurrent blood flow to cool blood flowing to the brain. This effectively controls the temperature of the brain. 

The hump stores up to 80 lb of fat, which the camel can break down into water and energy to meet its needs when resources are scarce; the hump also helps dissipate body heat.  If the hump is small, the animal can show signs of starvation. In a 2005 study, the mean volume of adipose tissues (in the external part of the hump that have cells to store lipids) is related to the dromedary's unique mechanism of food and water storage. In case of starvation, they can even eat fish and bones, and drink brackish and salty water. The hair is longer on the throat, hump and shoulders. Though the padded hooves effectively support the camel's weight on the ground, they are not suitable for walking on slippery and muddy surfaces.

Reproduction

Since camels have a slow growth rate; they reach sexual maturity only in advanced years. The age of sexual maturity varies geographically and depends on the individual, as does the reproductive period. Both sexes might mature by three to five years of age, though successful breeding could take longer. Mating occurs once a year, and peaks in the rainy season. The mating season lasts three to five months, but may last a year for older animals. 

During the reproductive season, males splash their urine on their tails and nether regions. To attract females they extrude their soft palate – a trait unique to the dromedary. As thr male gurgles copious quantites of saliva turns to foam and covers the mouth. Males threaten each other for dominance over the female by trying to stand taller than the other, making low noises and a series of head movements including lowering, lifting and bending their necks backwards. Males tries to defeat other males by biting the opponent's  legs and taking the head between his jaws. Copulation begins with foreplay; the male smells the female's genitalia and often bites her there or around her hump. The male forces the female to sit, then grasps her with his forelegs. Camelmen often aid the male insert his penis into the female's vulva. The male dromedary's  ability to penetrate the female on his own is disputed, though feral populations in Australia reproduce naturally. Copulation takes from 7 to 35 minutes, averaging 11 to 15 minutes. Normally, three to four ejaculations occur. The semen of a Bikaneri dromedary is white and viscous, with a pH of around 7.8.

A single calf is born after a gestation period of 15 months. Calves move freely by the end of their first day. Nursing and maternal care continue for one to two years. In a study to find whether young could exist on milk substitutes, two male, month-old camels were separated from their mothers and were fed on milk substitutes prepared commercially for lambs. For the first 30 days, the changes in their weights were marked. Each gained  and 1 kg, respectively, per day. They were found to have grown properly and weighed  135 kg and 145 kg – normal weights for male calves of that age.  Lactational yield can vary with species, breed, individual, region, diet, management conditions and lactating stage. The largest quantity of  milk is produced during the early period of lactation. The lactation period can vary between nine and eighteen months.

Dromedaries are induced ovulators.  Oestrus may be cued by the nutritional status of the camel and the daylength. If mating does not occur, the follicle, which grows during oestrus, usually regresses within a few days. In one study, 35 complete oestrous cycles were observed in five nonpregnant females over 15 months. The cycles were about 28 days long; follicles matured in six days, maintained their size for 13 days, and returned to their original size in eight days. In another study, ovulation could be best induced when the follicle reaches a size of . In another study, pregnancy in females could be recognized as early as 40 to 45 days of gestation by the swelling of the left uterine horn, where 99.5% of pregnancies were located.

Distribution

The dromedary has not occurred in the wild for nearly 2,000 years. Wild dromedaries inhabited arid regions, particularly the Sahara Desert. The original range of the camel’s wild ancestors was probably southern Asia and the Arabian peninsula. Its range included hot, arid regions of northern Africa, Ethiopia, the Near East and western and central Asia.  The dromedary typically thrives in areas with a long dry season and a short wet season. They are sensitive to cold and humidity, though some breeds can thrive in humid conditions.

In the early 21st century, the domesticated dromedary is found in the semi-arid to arid regions of the Old World. Africa has more than 80% of the world's total dromedary population; it occurs in almost every desert zone in the northern part of the continent. The Sahel marks the southern extreme of its range, which is nearly 2–3°S latitude where the annual rainfall is around 550 mm. The Horn of Africa has nearly 35% of the world's dromedaries, most of the region's stock is in Somalia, followed by Sudan and Ethiopia (as of the early 2000s). According to the Yearbook of the Food and Agriculture Organisation (FAO) for 1984, eastern Africa had about 10 million dromedaries, the largest population of Africa. Western Africa followed with 2.14 million, while northern Africa had nearly 0.76 million.  Populations in Africa increased by 16% from 1994 to 2005.

Feral dromedary populations occur in Australia, where it was introduced in 1840. The total dromedary population in Australia is 0.5 million as of 2005. Nearly 99% of the populations are feral, and have annual growth rate of 10%. Most of the Australian feral camels are dromedaries, with only a few Bactrian camels. Most of the dromedaries occur in Western Australia, with smaller populations in the Northern Territory, Western Queensland and northern South Australia.

In Asia, nearly 70% of the population occurs in India and Pakistan. The combined population of the dromedary and the Bactrian camel decreased by around 21% between 1994 and 2004. The dromedary is sympatric with the Bactrian camel in Afghanistan, Pakistan, and central and southwestern Asia. India has a dromedary population of less than one million, with most (0.67 million) in the state of Rajasthan. Populations in Pakistan decreased from 1.1 million in 1994 to 0.8 million in 2005 – a 29% decline. According to the FAO, the dromedary population in six countries of the Persian Gulf was nearly 0.67 million in 2003. In the Persian Gulf region the dromedary is locally classified into breeds including Al-Majahem, Al-Hamrah, Al-Safrah, Al-Zarkah and Al-Shakha, based on coat colour. The UAE has three prominent breeds; Racing camel, Al-Arabiat and Al-Kazmiat.

Domestication

The dromedary was probably first domesticated in Somalia or the Arabian Peninsula about 4,000 years ago.  In the ninth or tenth century BC, the dromedary became popular in the Near East. The Persian invasion of Egypt under Cambyses in 525 BC introduced domesticated camels to the area. The Persian camels were not well-suited to trading or travel over the Sahara; journeys across the desert were made on chariots pulled by horses.  The dromedary was introduced into Egypt from south-western Asia (Arabia and Persia). The popularity of dromedaries increased after the Islamic conquest of North Africa. While the invasion was accomplished largely on horseback, new links to the Middle East allowed camels to be imported en masse. These camels were well-suited to long desert journeys and could carry a great deal of cargo, allowing substantial trans-Saharan trade for the first time. In Libya, dromedaries were used for transport and their milk and meat constituted the local diet.

Dromedaries were also shipped from south-western Asia to Spain, Italy, Turkey, France, Canary Islands, the Americas and Australia. Dromedaries were introduced into Spain in 1020 AD and to Sicily in 1059 AD. Camels were exported to the Canary Islands in 1405 during the European colonisation of the area, and are still extant there, especially in Lanzarote and to the south of Fuerteventura. Attempts o introduce dromedaries into the Caribbean, Colombia, Peru, Bolivia and Brazil were made between the 17th and 19th centuries; some were imported to the western United States in the 1850s and some to Namibia in the early 1900s, but presently they exist in small numbers or are absent in these areas.

In 1840, about six camels were shipped from Tenerife to Adelaide, but only one survived the journey to arrive on 12 October that year. The animal, a male called Harry, was owned by the explorer John Ainsworth Horrocks. Harry was ill-tempered but was included in an expedition the following year because he could carry heavy loads. The next major group of camels were imported into Australia in 1860, and between 1860 and 1907 10 to 12 thousand were imported. These were used mainly for riding and transport.

Relationship with humans

The strength and docility of the dromedary make it popular as a domesticated animal. According to Bulliet, they can be used for a wide variety of purposes: riding, transport, ploughing, trading and as a source of milk, meat, wool and leather. The main attraction of the dromedary for nomadic desert-dwellers is the wide variety of resources they provide, which are crucial for their survival. It is important for several Bedouin pastoralist tribes of northern Arabia, such as the Ruwallah, the Shammar and the Mutayr.

Riding camels

Although the role of the camel is diminishing with the advent of technology and modern means of transport, it is still an efficient mode of communication in remote and less-developed areas.  The dromedary has been used in warfare since the 2nd century BC, and it remains popular for racing, particularly in the Arab world. Riding camels of Arabia, Egypt and the Sahara are locally known as the Dilool, the Hageen and the Mehara respectively; several local breeds are included within these groups.

The ideal riding camel is strong, slender and long-legged with thin, supple skin. The special adaptations of the dromedary's feet allow it to walk with ease on sandy and rough terrain and on cold surfaces. The camels of the Bejas of Sudan and the Anafi camel bred in Sudan are common breeds used as riding camels.

According to Leese, the dromedary walks with four speeds or gaits: walk, jog, fast run and canter. The first is the typical speed of walking, around 4 km/h. Jog is the most common speed, nearly 8 - on level ground. 
He estimated a speed of 14 - during a fast run, by observing northern African and Arabian dromedaries. He gave no speed range to describe the "canter", but implied it was a type of gallop that if induced could exhaust the camel and the rider. Canter could be used only for short periods of time, for example in races.

The ideal age to start training dromedaries for riding is three years, although they may be stubborn and unruly. At first the camel's head is controlled, and it is later trained to respond to sitting and standing commands, and to allow mounting. At this stage a camel will often try to escape when a trainer tries to mount it. The next stage involves training it to respond to reins. The animal must be given loads gradually and not forced to carry heavy loads before the age of six. Riding camels should not be struck on their necks, rather they should be struck behind the right leg of the rider. Leese described two types of saddles generally used in camel riding; the Arabian markloofa used by single riders and the Indian pakra used when two riders mount the same camel.

Baggage and draught camels

The baggage camel should be robust and heavy. Studies have recommended the camel should have either a small or a large head with a narrow aquiline nose, prominent eyes and large lips. The neck should be medium to long so the head is held high. The chest should be deep and the hump should be well-developed with sufficient space behind it to accommodate the saddle. The hindlegs should be heavy, muscular and sturdy. The dromedary can be trained to carry baggage from the age of five years, but must not be given heavy loads before the age of six. The hawia is a typical baggage saddle from Sudan. The methods of training the baggage camels are similar to those for riding camels.

Draught camel are used for several purposes including ploughing, processing in oil mills and pulling carts. There is no clear description for the ideal draught camel, though its strength, its ability to survive without water and the flatness of its feet could be indicators. It may be used for ploughing in pairs or in groups with buffaloes or bullocks. The draught camel can plough at around , and should not be used for more than six hours a day – four hours in the morning and two in the afternoon. The camel is not easily exhausted unless diseased or undernourished, and has remarkable endurance and hardiness.

Dairy products

Camel milk is a staple food of nomadic tribes living in deserts. According to a study, it consists of 11.7% solids, 3% protein, 3.6% fat, 0.8% ash, 4.4% lactose and 0.13% acidity (pH 6.5). The quantities of sodium, potassium, zinc, iron, copper, manganese, niacin and vitamin C were relatively higher than the amounts in cow milk. However, the levels of thiamin, riboflavin, folacin, vitamin B12, pantothenic acid, vitamin A, lysine, and tryptophan were lower than those in cow milk. The molar percentages of the fatty acids in milk fat were 26.7% for palmitic acid, 25.5% oleic acid, 11.4% myristic acid and 11% palmitoleic acid. Camel milk has higher thermal stability compared with cow milk, but it does not compare favourably with sheep milk.

Daily milk yield generally varies from  and from 1.3% to 7.8% of the body weight.  Milk yield varies geographically and depends upon the animals' diet and living conditions. At the peak of lactation, a healthy female would typically provide 9 kg milk per day. Leese estimated a lactating female would yield 4 to besides the amount ingested by the calf. The Pakistani dromedary, which is considered a better milker and bigger, can yield  when well-fed. Dromedaries in Somalia may be milked between two and four times a day, while those in Afar, Ethiopia, may be milked up to seven times a day.

The acidity of dromedary milk stored at 30 C increases at a slower rate than that of cow milk. Though the preparation of butter from dromedary milk is difficult, it has been carried out successfully in 1959 in the USSR. The cream of the dromedary milk, containing 4.2% fat, yielded 25.8% butter. In 2001, the ability of dromedary milk to form curd was studied; coagulation did not show curd formation, and had a pH of 4.4. It was much different from curd produced from cow milk, and had a fragile, heterogeneous composition probably composed of casein flakes.  Nevertheless, cheese and other dairy products can be made from camel milk. A study found bovine calf rennet could be used to coagulate dromedary milk. A special factory has been set up in Nouakchott to pasteurise and make cheese from camel milk.  Mystical beliefs surround the use of camel milk in some places; for example, it may be used as an aphrodisiac in Ethiopia. 

Meat

The meat of a five-year-old dromedary has a typical composition of 76% water, 22% protein, 1% fat, and 1% ash. The carcass, weighing 141 - for a five-year-old dromedary, is composed of nearly 57% muscle, 26% bone and 17% fat. A seven-to-eight-year-old camel can produce a carcass of 125 -. The meat is bright red to a dark brown or maroon, while the fat is white. It has the taste and texture of beef. A study of the meat of Iranian dromedaries showed its high glycogen content, which makes it taste sweet like horse meat. The carcasses of well-fed camels were found to be covered with a thin layer of good quality fat. In a study of the fatty acid composition of raw meat taken from the hind legs of seven one-to-three years old males, 51.5% of the fatty acids were saturated, 29.9% mono-unsaturated, and 18.6% polyunsaturated. The major fatty acids in the meat were palmitic acid (26.0%), oleic acid (18.9%) and linoleic acid (12.1%). In the hump, palmitic acid was dominant (34.4%), followed by oleic acid (28.2%), myristic acid (10.3%) and stearic acid (10%). 

Dromedary slaughter is more difficult than the slaughter of other domestic livestock such as cattle, because of the size of the animal and the significant manual work involved. More males that females are slaughtered. . Though less affected by mishandling than other livestock, the pre-slaughter handling of the dromedary plays a crucial role in determining the quality of meat obtained; mishandling can often disfigure the hump. The animal is stunned, seated in a crouching position with the head in a caudal position and slaughtered. The dressing percentage – the percentage of the mass of the animal that forms the carcass – is 55–70%, more than the 45–50% of cattle. Camel meat is rarely consumed by African camel herders, who use it only during severe food scarcity or for rituals. Camel meat is processed into food items such as burgers, patties, sausages and shawarma. Dromedaries can be slaughtered between four and ten years of age. As the animal ages, the meat grows tougher and deteriorates in taste and quality.

A 2005 report issued jointly by the Ministry of Health (Saudi Arabia) and the United States Centers for Disease Control and Prevention details five cases of bubonic plague in humans resulting from the ingestion of raw camel liver. Four of the five patients had severe pharyngitis and submandibular lymphadenitis. Yersinia pestis was isolated from the camel's bone marrow, from the jird (Meriones libycus) and from fleas (Xenopsylla cheopis) captured at the camel's corral. 

Camel hair, wool and hides

Camels in hot climates generally do not develop long coats. Camel hair is light, and has low thermal conductivity and durability, and is thus suitable for manufacturing warm clothes, blankets, tents and rugs. Hair of highest quality is typically obtained from juvenile or wild camels. In India, camels are clipped usually in spring and around 1 - hair is produced per clipping. In colder regions one clipping can yield as much as . A dromedary can produce 1 kg wool per year, whereas a Bactrian camel has an annual yield of nearly 5 -. Dromedaries under the age of two years have a fine undercoat that tends to fall off and should be cropped by hand. Little information about camel hides has been collected but they are usually of inferior quality and are less preferred for manufacturing leather.
Bactrian Bactrian (disambiguation)
bactrian bactrian disambiguation
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 What type of camel has two humps? 

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