Nubian ibex

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.

Ethiopia

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.

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.

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. Gestation lasts 5 months. Litters of 1–2 kids are born between March and July, although the majority of births are synchronized in a 3–4 week period that peaks in late March and April. Females leave the herd to give birth in a secluded space. Newborns can stand within 15 minutes of birth, and can nurse within two hours. The mother and young rejoin the herd in a few days, joining other mothers and young to form a crèche for several weeks. Leaving kids in a sheltered crèche allows mothers to seek out richer food patches and spaces that are farther from cliffs, compared to mothers that keep their kids with them at all times. Kids are weaned around 4 months old. Females reach mature size at age 3–4, while males reach it around 6 years old. Nubian ibex can live up to 12 years in the wild and 18 years in captivity.

Nubian ibex are the smallest ibex species, following Bergmann's rule. They stand around 65–75 cm (26–30 in) tall at the shoulder. They are sexually dimorphic: males are significantly larger than females, with males averaging 52–74.7 kg (115–165 lb) and females 25.3–32.7 kg (56–72 lb). 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 1 m (3 ft 3 in) in length, while in females they are much smaller, reaching around 30 cm (12 in). 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.

In the 1970s, researchers in Lahav, Israel, began breeding and studying hybrids of Nubian ibex and domestic goats, called "Yaez" ("יעז"). In one study of these hybrids, plasma testosterone peaked in August and testis size peaked in September–October. In a study on reproduction, researchers found that females were more likely to abort their young if they were first-time pregnancies and triplets (as opposed to smaller litters). Mortality rates of young were highest in spring and lowest in winter. Kid mortality rates increased with a higher proportion of ibex genes. When researchers compared the growth rate of male goat and Yaez kids, they found that young goats experience a higher growth rate in spring while Yaez kids grow faster in summer. Yaez kids were found to be more susceptible to disease and put on less weight when compared to their purebred parents.

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.