Is infant-carrying a courtship strategy in callitrichid primates?

Three predictions arising from the proposal that infant-carrying serves as a form of courtship in callitrichid primates were tested, using data from captive common marmosets, Callithrix jacchus and cotton-top tamarins, Saguinus oedipus. The first prediction, that males would be more likely to successfully copulate while carrying infants than while not carrying infants, was not supported in either species. In common marmosets, males were less likely to copulate while carrying infants. This relation may reflect the lower activity levels and increased vigilance required by those individuals transporting infants. The second prediction, that the overall percentage of time that males spent carrying infants would be related to overall frequency of copulations during fertile periods, was also not supported for either species. The third prediction was that, if females selected mates relative to their infant-care ‘performance’, males should be more solicitous of the breeding female’s efforts to relinquish the infant to another carrier than to the efforts of other group members. If so, then males should retrieve harassed infants from mothers more frequently than from other group members; this prediction was not supported. The results of this study offer no support for the contention that infant care serves as a form of courtship in callitrichid primates. ? 1997 The Association for the Study of Animal Behaviour Relations between infant-care behaviours by males and mating access to females have been proposed for a wide variety of animals. In some species, male parental care may conflict with pursuit of further breeding opportunities. In some cichlid fish, for example, male investment in care of young or nests may be reduced if breeding Care of infants by males is less common in mammals than in either fish or birds; where it occurs, however, relations between male parental behaviour and mating access to females may also exist. One mammalian group in which male infant care is common is the primates of the family Callitrichidae (marmosets and tamarins). Because 0 access to other females is increased (Keenleyside 1983). In other species, males may alter their infant-care behaviours relative to previous sexual access to the breeding female. In some polyandrous birds, for example, there is evidence that the willingness of males to participate in care of nestlings is to some degree dependent upon sexual access to the breeding female (Brown 1987; Davies et al. 1992). Such relations might be expected in species in which mating behaviour precedes the period of care by a relatively short period (e.g. 10–20 days in dunnocks: Davies et al. 1992). Correspondence: S. D. Tardif, Dept. of Biological Sciences, Cunningham Hall, Kent State University, Kent, OH 44242-0001, U.S.A. (email: stardif@phoenix. kent.edu). K. Bales is at the Department of Zoology, University of Maryland, College Park, MD 20742-4415, U.S.A. 0003–3472/97/051001+07 $25.00/0/ar960353 ? 1 callitrichid males experience a 130–180 day delay between mating and infant care (i.e. the length of gestation), little opportunity exists for a direct causal link between mating and subsequent willingness to care for infants. Therefore, it is not surprising that callitrichid males do not appear to apportion infant care relative to previous access to mating (Cleveland & Snowdon 1984; Wambolt et al. 1988; Baker et al. 1993; Tardif 1996). A different relation between infant care by males and mating has been proposed in this taxonomic group, however. Rylands (1982, 1996), Price (1990) and Ferrari (1992) have proposed that infant-carrying by potential breeding males may function as a form of courtship, given that callitrichid primates typically ovulate 10–30 days after parturition (Hearn 1983; Ziegler et al. 1987) and are therefore fertile during the time when infants 1997 The Association for the Study of Animal Behaviour