The Nubian ibex (Capra nubiana) is a desert-dwelling species of goat (genus Capra) found in mountainous areas of northern and northeast Africa, and the Middle East. Historically considered a subspecies of the Alpine ibex (C. ibex), it is now recognized as a distinct species. The wild population is estimated at 4,500 mature individuals, and it is classified as vulnerable by the International Union for Conservation of Nature.
Taxonomy
Classification The Nubian ibex was first identified in modern science by Frédéric Cuvier in his 1825 Histoire naturelle des mammifères: avec des figures originales, coloriées, dessinées d'aprèsdes animaux vivans, in which he illustrated the animal with the label "Bouc sauvage de la Haute-Égypte" ("Wild goat of Upper Egypt").É. Geoffroy and F. Cuvier. 1825. Hist. Nat. Mammifères, pt. 3, 6(50):2 pp. "Bouc sauvage de la Haute-Egypte" It was initially classified as Capra ibex nubiana, a subspecies of the Alpine ibex (C. ibex) identified by Carl Linnaeus in 1758. Other early researchers classified it as a now-defunct synonym, C. sinaitica, or the Sinai ibex. While it was referred to as its own species, C. nubiana, by some authors in the 19th and early 20th Century, the first widely recognized researcher to classify the Nubian ibex as a unique species, and not as a subspecies, was Hans-Peter Uerpmann in his 1987 book, The ancient distribution of ungulate mammals in the Middle East: fauna and archaeological sites in Southwest Asia and Northeast Africa. Capra nubiana, the Nubian ibex, is now broadly accepted by scientists as a unique species.
Fossil history The earliest remains of the Nubian ibex in the Palestine region date back approximately 150,000 years to the Pleistocene, and it has been continually present in the region since then. In spite of the growing presence of livestock such as domesticated goats over the last 10,000 years, Nubian ibex have remained in the region throughout this time. However, its abundance has fluctuated in places like Ein Gedi, where it showed an increase in population in the late Holocene between approximately 5,165 and 950 years ago. Radiocarbon dated bones from archaeological excavations indicate that the Nubian ibex has been in a predator-prey relationship with the Arabian leopard throughout the Holocene.
Phylogeny
The Nubian ibex shares a genus, Capra, with all other ibex and goats. Phylogenetic reconstructions of the ibex/goat family tree have mixed results, with different studies reaching different conclusions. One Y-chromosomal DNA analysis suggests two clades (subgroups) within the genus; the first clade contains domestic goats (C. hircus), wild goats (C. aegagrus), and markhors (C. falconeri). The second clade contains all other ibex, including the Nubian ibex. In this analysis, the Nubian ibex is most closely related to the Siberian ibex (C. sibirica). However, when the same study analyzed mitochondrial DNA, it was suggested that all members of Capra are in one clade except for the Siberian ibex. The study's authors provide potential explanations for this discrepancy, including a possible ancient hybridization of the ancestors of the two Y-chromosome clades.
A separate mitochondrial study suggests that the Nubian ibex forms a separate, more ancient offshoot from most other ibex. An additional Y-chromosomal DNA and mitochondrial DNA study concludes that Nubian ibex are most closely related to Ethiopia's Walia ibex (C. walie), and they may have separated about 800,000 years ago. Another study used multidimensional scaling (MDS) to suggest that Nubian ibex are more closely related to Alpine ibex and European ibex than to all others.
The following cladogram of seven Capra species is based on 2022 mitochondrial evidence:
Genetic analysis suggests that their population was relatively high during the last interglacial period, and decreased during the last ice age. The genetic makeup of Nubian ibex as a species has remained unchanged for at least 2,000 years.Kahila Bar-Gal, G. 2000. Genetic change in the Capra species of Southern Levant over the past 10,000 years as studied by DNA analysis of ancient and modern populations. Ph.D. thesis, Hebrew Univ., Jerusalem. 163 pp. There is genetic evidence of ancient gene introgression between Nubian ibex and bezoar ibex, which, in turn, interbred with domestic goats and left genetic signatures.
Description
Nubian ibex are the smallest ibex species, following Bergmann's rule. They stand around tall at the shoulder. They are sexually dimorphic: males are significantly larger than females, with males averaging and females .
+ Weights of Nubian ibex by age classesSex & AgeNumber ofindividualsMeanweight (kg)Female (~4 years)2232.7Male (2–3 years)537.8Male (4 years)353.7Male (~7 years)874.7 They are a light tan color, with a white underbelly; males also have a dark brown mane down their backs. Their legs have a black and white pattern. They have a lighter rump with a dark brown tail. Males begin growing a beard at age 2 or 3, which continues to grow longer and darker as they age. During the autumn breeding season, mature males grow a "rutting fur" on their breast and sides which is very dark brown. It appears in October in 3–4-year-old males, but it may appear as early as July or August in older males age 6 and up. However, not all males develop rutting fur, even at a mature age.
Nubian ibexes have long, thin horns that extend up and then backwards and down. In males, these reach around in length, while in females they are much smaller, reaching around . Male horns are thicker than female horns, and grow large bulges which prevent the horns from sliding while the males are locked in combat. Male horn growth plateaus around age 7–8, where as female horn growth plateaus around age 4–6. There is a significant relationship between the individual's age and the number of horn ridges.
Distribution
Historically, Nubian ibex were distributed across the Middle East and Northeastern Africa. Its range today is within Egypt, Jordan, Oman, Israel, Palestine, Saudi Arabia and Sudan. It was extirpated in Lebanon, though a captive breeding and reintroduction process is underway. It has been extirpated in Syria. Its presence is uncertain in Ethiopia, Eritrea and Yemen.
Ecology and behavior Feeding Nubian ibex live in rough, dry, mountainous terrain, where they eat mainly grasses and leaves, especially from Acacia trees (Genus Vachellia). They forage for food on the ground and may also rear up on their hind legs to reach leaves in trees. They can climb into trees while feeding. They reduce feeding on plants with strong defenses, such as tannins and thorns. Preferred plants vary depending on the amount of rain; rainy winters result in higher feeding preference for annual plants over perennials. Ibex preferentially feed in spaces that are close to cliffs where they can easily escape predators, demonstrating a Landscape of Fear: the farther from cliffs, the more vigilant ibex become. Ibex will also spend more time feeding in green patches with high nutritional quality and that are closer to water sources. Female Nubian ibex in Oman have been recorded consuming small bone fragments (osteophagy), a common behavior in mammals to supplement calcium and phosphorus in their diet.
Ecological relationships
They are preyed upon by Arabian leopards (Panthera pardus nimr), Arabian wolves (Canis lupus arabs), golden jackals (Canis aureus), caracals (Caracal caracal), red foxes (Vulpes vulpes), golden eagles (Aquila chrysaetos), Eurasian eagle owls (Bubo bubo), and bearded vultures (Gypaetus barbatus). When alarmed, they emit a shrill call to alert other ibex of danger. They share their habitat with numerous other herbivores, including rock hyrax (Procavia capensis), Arabian oryx (Oryx leucoryx), gazelles (Genus gazella), and Asiatic wild ass (Equus hemionus). Nubian ibex have a mutualistic relationship with Tristram's starling (Onycognathus tristrumil), a small bird that eats the parasites on the ibex's skin.
They may host parasites including: the ibex fly (Lipoptena chalcomelanea), blood sucking lice (Linognathus africanus and Damalinia sp.), ticks (Hyalomma rhipicephaloides, Boophilus annulatus, and others), mites (Psoroptes cuniculi and Sarcoptes scabiei), biting flies (Oestrus sp.) and fleas. They have also been found with brain cysts caused by the parasite Taenia multiceps.
Disease Nubian ibex have been detected with a strain of the malignant catarrhal fever (MCF) virus group of ruminant rhadinoviruses, closely related to caprine herpesvirus 2 (CpHV-2) found in domestic goats. Nubian ibex in Qatar's Al Wabra Wildlife Preservation have been infected by caprine pleuropneumonia. In Jerusalem's Biblical Zoo, the Nubian ibex herd suffered an outbreak of peste des petits ruminants. A trail camera study identified ibex infected with caseous lymphadenitis, infectious keratoconjunctivitis, contagious ecthyma, and infections from biting flies.
Social behavior Ibex are social, and herds tend to consist of females, young, and males up to the age of about three years. Herds are typically up to 20 individuals, but are sometimes as high as 50. Groups can also be smaller (less than 10) in habitats with fewer resources. Female herds are often composed of related individuals that follow a dominance hierarchy. Female herds tend to remain around permanent water sources throughout the year, whereas males are more transient. The males are solitary or form more transitory bands of up to eight individuals. During the breeding season, males join the female-based herds for the six- to eight-week rut. Large males then do battle with much clashing of horns.
Movement Nubian ibexes are diurnal, meaning they are active during the day, and rest at night. Like other ibex and goats, Nubian ibex spend much of their time on and around cliffs, which offer safety from potential predators. Ibex perceive a greater predation risk as they move farther away from cliffs. They climb and leap with ease, spanning several meters horizontally and vertically in a single jump. Ibex typically traverse cliffs in single file when possible, and keep relatively horizontal in their orientation. Their repeated movement over time creates well-worn hillside trails.
Ibex migrate throughout the day and throughout the year. During the day, they navigate between food patches as they forage. They may rest throughout the day to chew their cud, especially around midday. Additionally, on cold winter days, ibex in Egypt have been documented following the path of the sun each day to stay warm. At night, they sleep on cliff sides in small depressions that they dig. These shallow diggings create microhabitats where a diverse range of seedlings can germinate, adding to the habitat's diversity. In winter and early spring, the Middle East's rainy season, ibex often disperse to open plateaus where they can feed on new plant life. In the hot, dry summer, they congregate around shaded oases with water and greenery.
Reproduction and life history Mating season is typically in October and November, during which a dominant male will pursue several females. Males produce a strong scented secretion when females are in estrous. As they pursue potential mates, they curl their lips and smell the females' anal region. Males can reach breeding maturity as young as 2 years, but may not be allowed to mate until age 5 when they are strong enough to fend off rival males. Females can breed as young as six months old, but often don't breed until age 1–3. Studies suggest that some Nubian ibex subpopulations are developing a second mating season in the spring, in response to hyper-arid climates.