A Preliminary Field Study of the Moustached Tamarin Monkey (Saguinus mystax) in Northeastern Peru: Questions Concerned with the Evolution of a Communal Breeding System

Abstract

A preliminary field study was conducted on moustached tamarin monkeys (Saguinus mystax) inhabiting Padre Isla, a small island in the Amazon Basin of northeastern Peru. Data presented indicate that groups are generally composed of 3-8 individuals including a single breeding female, 1-3 reproductively active males, nonreproductive adult females, and offspring. Migration of adults and subadults into and out of established groups is common, and it is unlikely that S. mystax social units represent nuclear or extended families. It is argued that rather than tending towards monogamy, the reproductive biology and mating activities of moustached tamarins are better understood in terms of a communal breeding system. In the case of this and perhaps other callitrichid species, such a system appears to involve female promiscuity and the participation of reproductively active adult male group members in caring for the young. The hypothesis that there is an important relationship between the number of adult male ‘helpers’ and infant survival is discussed.

Opportunistic mothers: female marmosets (Callithrix kuhlii) reduce their investment in offspring when they have to, and when they can

“…The energetic demands of producing and rearing callitrichid infants are often cited as factors necessitating some form of assistance for callitrichid females (e.g., Leutenegger, 1980;Garber, et al, 1984;Goldizen, 1987;Dunbar, 1988;Wright, 1990;Price 1992c), yet the response of individual females to two of the hallmarks of callitrichid reproduction-conceptionduring lactation, and alloparental assistance-have not been previously investigated. The results of the studies presented here suggest that female marmosets are equipped with the ability to relinquish infant care to other caregivers when conception occurs during the early postpartum period and when experienced alloparental assistance is available.…”

“…These energetic demands have often been cited as factors necessitating some form of assistance for callitrichid females (e.g., Leutenegger, 1980;Garber, et al, 1984;Goldizen, 1987;Dunbar, 1988;Wright, 1990;Price 1992c), and, indeed, cooperative rearing of offspring is a hallmark of callitrichid reproduction (see review in Tardif, 1996). In every species studied to date, females share the responsibility of infant care with members of their family or social group (e.g., Cleveland and Snowdon, 1984;Goldizen, 1987).…”

Does the milk of callitrichid monkeys differ from that of larger anthropoids?

“…Callitrichids are also distinguished among anthropoids by a cooperative system of infant care that includes provisioning of infants by other members of the group during the weaning period [Garber et al, 1984;Tardif et al, 1993]. This food-sharing behavior likely reduces the infants' reliance on milk and probably reduces the energy demand on mothers.…”

Hormonal changes related to paternal and alloparental care in common marmosets (Callithrix jacchus)

“…For fathers, their participation in infant care might increase their access to the breeding female (Price, 1990). For older offspring, it might improve their infant care skills by gaining experience with siblings (Hoage, 1978;Epple, 1978;Tardif et al, 1984;Cleveland and Snowdon, 1984;Pryce, 1988Pryce, , 1993Baker and Woods, 1992;Snowdon, 1996;Sousa et al, 1997), increase the likelihood of inheriting a breeding position by staying in the social group (Goldizen and Terborgh, 1989;Ferrari and Diego, 1992;Baker et al, 1993), especially in saturated areas, since breeding opportunity outside the group may be limited and increase inclusive fitness gains through caring for and improving the survival of relatives (Garber et al, 1984). On the other hand, the costs for fathers and older offspring related to caring behavior seem to be the energetic cost of infant transport during traveling (Kirkwood and Underwood, 1984;Goldizen, 1987;Price, 1992;Sanchez et al, 1999), the increased risk of predation leading to the use of anti-predator strategy by caretakers (Caine, 1993;Tardif, 1994Tardif, , 1997Snowdon, 1996), and reduced foraging time during infant transport (Goldizen, 1987;Price, 1992;Digby and Barreto, 1996).…”