then retire at night in highly foliated areas to protect themselves from predators during slumber. Conflict There is often strife between neighboring groups of moustached tamarins due to limited food resources, especially near large feeding trees. Vocal battles can arise, with long calls that consist of short syllables at a high frequency. This type of conflict occurs between groups that are 25 meters or more apart. Fights can be more aggressive however, often including alarm calls, visual contact, scent marking and a series of chases and retreats. Adult males attack, inducing combative and loud vocalizations, while subadults chase one another. Subsequently, there is a period of calm, and both groups forage for food and subadults examine the opposing group for mating opportunities. The frequency of aggressive encounters increases during the breeding season and the majority of copulations occur during or directly after an aggressive encounter. Vocalizations Vocalizations allow moustached tamarins to distinguish between individuals, organize group movements, and ensure all members are accounted for. If individuals become separated, individuals of the same group will produce 2 to 3 second long vocalizations to indicate their location. These calls consist of repeated short, frequency-modulated syllables ranging from 8 to 12 kilohertz. In the morning, moustached tamarins make calls to each other to coordinate movement for the day towards specific foraging sites. Young tamarins also make vocalizations while they run and chase each other during play. Reproduction The reproduction season of the moustached tamarin monkey is November to March, during which the oldest female reproduces. Females go into oestrus for about 17 days. Their gestation period is about 145 days, after which females give birth. Other members of the group help to take care of the infants, allowing the female to give birth more than once a year. The eldest female frequently bears twins because they ovulate multiple ova during each reproductive cycle. The twins can be up to a quarter of the mother’s size at birth. Females reach reproductive maturity at about 480 days, and males at 540 days. Both sexes migrate to a different group in adulthood to avoid the risk of inbreeding. Moustached tamarins practice a variety of mating systems: polyandry, polygyny or polygynandry. The mothers often receive help from up to 4 or 5 other members of the group. In polyandrous groups, the alpha male tolerates the presence of other males who can provide infant-care. Not having enough helpers