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BiologyThis adaptable species is highly promiscuous and both males and females mate with as many members of the opposite sex as possible. They travel in groups of between 8 and 180 individuals, usually with two to four times as many females as males. Breeding takes place whenever the seasons permit, with no defined period in non-seasonal areas. Females undergo a regular oestrus cycle of 26 – 29 days, but unlike many other macaques, the genital region swells and darkens in colour only slightly during the fertile period, and only in younger adult females (4). Gestation lasts around 165 days, and females give birth to a single young or, rarely, twins. The young is fed milk for a year, first clinging to the mother's belly, but riding on her back when older. After weaning, female juveniles may remain with the same group whereas males often disperse to another. Females become sexually mature between 2.5 and 4 years and males between 4.5 and 7 years. Females who reach ages of more than 25 years go through the menopause, eventually becoming infertile (6). The rhesus macaque shows dominance hierarchies in both sexes, but more so in males. The status of each individual is inherited from its mother. There may be confrontations between groups, but these are rare as weaker groups actively avoid stronger groups. Females within groups can be very loud, but rarely fight as they are usually closely related (4). All members of the group practise social grooming for pleasure, health and as a form of submission and appeasement. Appeasement is also shown by the fear grimace in which the lips are retracted to reveal the clenched teeth. Staring with the mouth open signifies threat and putting the tail vertically upwards indicates aggressive confidence. Infants attract their mother's attention by cooing, and adult females will also coo to attract a male. Males respond by lip-smacking as an invitation to mate (5). The diet of the rhesus macaque varies by region. They are omnivorous opportunists, feeding mainly on roots, herbs, insects, crop plants and small animals. They are good swimmers and will cross water to find food (4).