according to the kin selection theory, but also act spitefully toward one another. Reproduction After a gestation period of 162–193 days, the female gives birth to one infant. The infant's weight at birth is about . Infants are born with black fur which will begin to turn to a grey or reddish-brown shade (depending on the subspecies) after about three months of age. This natal coat may indicate to others the status of the infant, and other group members treat infants with care and rush to their defense when distressed. Immigrant males sometimes kill infants not their own in order to shorten interbirth intervals. High-ranking females will sometimes kidnap the infants of lower-ranking females. These kidnappings can result in the death of the infants, as the other female is usually not lactating. A young juvenile stays mainly with its mother and relatives. As male juveniles get older, they become more peripheral to the group. Here they play together, forming crucial bonds that may help them when they leave their natal group. Males that emigrate with a partner are more successful than those that leave alone. Young females, though, stay with the group and become incorporated into the matriline into which they were born. Male crab-eating macaques groom females to increase the chance of mating. A female is more likely to engage in sexual activity with a male that has recently groomed her than with one that has not. Diet Despite its name, the crab-eating macaque typically does not consume crabs; rather, it is an opportunistic omnivore, eating a variety of animals and plants. Although fruits and seeds make up 60 - 90% of its diet, it also eat leaves, flowers, roots, and bark. It sometimes preys on vertebrates including bird chicks, nesting female birds, lizards, frogs, and fish, invertebrates, and bird eggs. In Indonesia, it has become a proficient swimmer and diver for crabs and other crustaceans in mangrove swamps. In Bukit Timah, Singapore its diet consists of 44% fruit, 27% animal matter, 15% flowers and other plant matter, and 14% food provided by humans. The crab-eating macaque exhibits particularly low tolerance for swallowing seeds. Despite its inability to digest seeds, many primates of similar size swallow large seeds, up to , and simply defecate them whole. The crab-eating macaque, though, spits seeds out if they are larger than . This decision to spit seeds is thought to be adaptive;