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BiologyIn summer, the goitered gazelle lives in small family groups of no more than 10 individuals, whilst in winter, large herds of dozens, hundreds, or even thousands (in Asia) of animals congregate together (2) (9). This herding behaviour coincides with the breeding season from September to January, during which solitary adult males become territorial and use urine and dung to mark and indicate ownership of their territory within this herd (2) (16). Males also use their expanded throats at this time to emit hoarse bellows, and glandular secretions are smeared on surrounding objects (2) (16). Meanwhile, sub-adult males form bachelor groups of up to five individuals, without individual territories. By contrast, females and young gather in herds of 10 to 30 gazelles during that time. Mating is polygamous, with males chasing females only inside their territory. Territorial males chase females to keep them in their territory and banish any other males, including yearlings. While most males mate with 2 to 12 females, rarely more (to 30 females in some cases), some do not gain access to any females at all. After the rut, goitered gazelles gather in large, often mixed groups of up to 50 individuals, but by spring, males leave mixed groups, and males and females form groups independently. Pregnant females leave their (female) groups and become solitary as it gets close to the time of birth (4) (17). Gestation lasts 148 to 159 days, with calving occurring from March to July, although most females give birth during several days in May (April in Saudi Arabia, and June in Mongolia). Young and old females have a single newborn, but most adult females (75%) have twins, which is rare for other gazelle species. After birth a newborn hides alone while its mother grazes or lies within 50 to 500 m from him. Females lead their infants to new hiding places after each nursing, and twins are bedded 50 to 1000 m apart during the first four to six days. Young start following their mother regularly at the age of 2 to 2.5 months (Kingswood and Blank, 1996), and are weaned after four to five months (2). Some young females have their first oestrus at the age of six months, although most do not begin to breed until 18 months. Males may sire offspring at the age of 10 to11 months, but usually begin to breed only at 2.5 to 3 years of age. (11). Males are reproductive until 10 to 11 years old, though usually they do not live more than five to six years in the wild, and females can bear until the age of 13 to 14 years old (18), typically living 8 to 12 years in the wild (5). During the summer months, goitered gazelles graze most active in the early morning and late afternoon, feeding on grasses, leaves and shoots (2), but in areas with heavily poaching they become to be partly nocturnal (19) (12). Every gazelle eats 6 kg of forage a day, about 30% of its body weight and daily water intake is 2 to 4 litres (11). In the midday heat, these animals shelter in the shade and keep cool by excavating shallow pits to lie in, where the earth is cooler. This midday break is significantly reduced or even eliminated during the cooler winter months (2) (4) (11).