Wild Saddleback Tamarins Research Articles

Variable infant care contributions in cooperatively breeding groups of wild saddleback tamarins.

Among non-human primates, alloparental infant care is most extensive in callitrichines, and is thought to be particularly costly for tamarins whose helpers may suffer increased energy expenditure, weight loss, and reduced feeding time and mobility. The costs and benefits of infant care likely vary among group members yet very few wild studies have investigated variable infant care contributions. We studied infant care over an 8-month period in four wild groups of saddleback tamarins in Bolivia to evaluate: (a) what forms of infant care are provided, by whom, and when, (b) how individuals adjust their behavior (activity, vigilance, height) while caring for infants, and (c) whether individuals differ in their infant care contributions. We found that infant carrying, food sharing, and grooming varied among groups, and immigrant males-those who joined the group after infants were conceived-participated less in infant care compared to resident males. Adult tamarins fed less, rested more, and increased vigilance while carrying infants. Although we did not detect changes in overall activity budgets between prepartum and postpartum periods, tamarins spent more time scanning their environments postpartum, potentially reflecting increased predation risk to both carriers and infants during this period. Our study provides the first quantitative data on the timing and amount of infant carrying, grooming, and food transfer contributed by all individuals within and among multiple wild groups, filling a critical knowledge gap about the factors affecting infant care, and highlighting evolutionary hypotheses for cooperative breeding in tamarins.

The gut microbiome and metabolome of saddleback tamarins (Leontocebus weddelli): Insights into the foraging ecology of a small-bodied primate.

Body mass is a strong predictor of diet and nutritional requirements across a wide range of mammalian taxa. In the case of small-bodied primates, because of their limited gut volume, rapid food passage rate, and high metabolic rate, they are hypothesized to maintain high digestive efficiency by exploiting foods rich in protein, fats, and readily available energy. However, our understanding of the dietary requirements of wild primates is limited because little is known concerning the contributions of their gut microbiome to the breakdown and assimilation of macronutrients and energy. To study how the gut microbiome contributes to the feeding ecology of a small-bodied primate, we analyzed the fecal microbiome composition and metabolome of 22 wild saddleback tamarins (adult body mass 360-390 g) in Northern Bolivia. Samples were analyzed using high-throughput Illumina sequencing of the 16 S rRNA gene V3-V5 regions, coupled with GC-MS metabolomic profiling. Our analysis revealed that the distal microbiome of Leontocebus weddelli is largely dominated by two main bacterial genera: Xylanibacter and Hallella (34.7 ± 14.7 and 22.6 ± 12.4%, respectively). A predictive analysis of functions likely carried out by bacteria in the tamarin gut demonstrated the dominance of membrane transport systems and carbohydrate metabolism as the predominant metabolic pathways. Moreover, given a fecal metabolome composed mainly of glucose, fructose, and lactic acid (21.7 ± 15.9%, 16.5 ± 10.7%, and 6.8 ± 5.5%, respectively), the processing of highly fermentable carbohydrates appears to play a central role in the nutritional ecology of these small-bodied primates. Finally, the results also show a potential influence of environmentally-derived bacteria in colonizing the tamarin gut. These results indicate high energetic turnover in the distal gut of Weddell's saddleback tamarin, likely influenced by dominant bacterial taxa that facilitate dietary dependence on highly digestible carbohydrates present in nectar, plant exudates, and ripe fruits.

On the Relationship between Scent-Marking and Territoriality in Callitrichid Primates

Across a diverse range of animal groups, scent-marking is integrally related to the defense of territories and maintenance of social status. However, using data from a field study of wild saddleback tamarins (Saguinus fuscicollis), the authors of a recent paper claimed to find no evidence to support a relationship between scent-marking and territorial defense. Here I review the same evidence and argue that the data are consistent with the idea that scent-marking plays a critical role in territorial defense. This argument includes an attempt to clarify some misconceptions about the scent-marking mechanism that exist in the literature. I then reexamine the evidence in light of a proposed alternative function for scent-marking (that scent marks are used to explore reproductive opportunity and achieve extragroup copulations), and highlight some critical tests that could serve to distinguish between the two functional interpretations. Scent-marking could serve both in territorial signaling and in signaling to mates, but current evidence suggests that territorial defense is more, or at least equally, likely to be the primary function of scent-marking in callitrichids.

Can Overmarking Be Considered as a Means of Chemical Mate Guarding in a Wild Callitrichid?

Mate guarding is a male strategy to monopolize matings and thus to ensure paternity. Since in callitrichids female reproductive status is advertised by scent marks, one may expect mate guarding by chemical means. We addressed this question during an episode of consortship observed in a polyandrous trio of wild saddleback tamarins (Saguinus fuscicollis). During consortship, the consort male was the only one to allomark the female. Scent marking frequency decreased for all individuals, although the consort male marked more than the other male during consortship, while there was no difference in the previous period. During consortship, almost 50% of female scents were overmarked by the consort, and more than 56% of the consort’s scent marks were employed to overmark the female’s scents. Therefore, the other male had limited access to female scent marks. Mate guarding may thus have a chemical component in tamarins, and olfactory communication may play an important role in mating competition.

Interspecific communication in mixed-species groups of tamarins: evidence from playback experiments

Long-call vocalizations have been hypothesized to serve as communicative signals both within and between tamarin species. Prior evidence for the use of long calls as interspecific signals, however, is based solely on observations of apparent countercalling between species. I conducted playback experiments with groups of wild saddle-back tamarins, Saguinus fuscicollis, and emperor tamarins, S. imperator, to test the hypothesis that long calls function as interspecific signals between tamarin species forming polyspecific associations. Results show that in the absence of any other external cues, lone groups of saddle-back tamarins and emperor tamarins respond to the playback of long calls from both conspecific group members and heterospecific tamarins with which they associate. Playback of long calls from heterospecific tamarins elicited long calls and approaches towards the speaker. These findings are consistent with the hypothesis that long calls serve as interspecific signals between associating tamarin species.

Infanticide in a group of wild saddle-back tamarins,Saguinus fuscicollis

An infanticide was observed in a group of wild saddle-back tamarins, Saguinus fuscicollis. The newborn singleton was killed by its mother after it had fallen from the carrier several times. This infanticide may represent a case of parental manipulation: the mother terminated investment in an offspring that probably had a low chance of survival. Also, stress associated with the simultaneous pregnancy of another adult female in the group may have played a role.

Infanticide in a group of wild saddle-back tamarins, Saguinus fuscicollis

Infanticide in a group of wild saddle-back tamarins, Saguinus fuscicollis

Infanticide in a group of wild saddle-back tamarins, Saguinus fuscicollis.

An infanticide was observed in a group of wild saddle-back tamarins, Saguinus fuscicollis. The newborn singleton was killed by its mother after it had fallen from the carrier several times. This infanticide may represent a case of parental manipulation: the mother terminated investment in an offspring that probably had a low chance of survival. Also, stress associated with the simultaneous pregnancy of another adult female in the group may have played a role.

Birth seasonality in cotton-top tamarins (saguinus oedipus) despite constant food supply and body weight

Goldizen et al. (1988) reported that wild saddle-back tamarins (Saguinus fuscicollis, Callitrichidae) show birth seasonality that is correlated with food supply and body weight. They suggested a sequence of ultimate causality in which shortage of food leads to reduced body weight which leads to timing of weaning and lactation when resources are more abundant. Cotton-top tamarins in captivity show birth seasonality despite constant food supply and body weight. Although natural availability of fruit and insects (which are key foods for tamarins) is related to rainfall, birth seasonality and body weight in captive cotton-top tamarins are unrelated to rainfall. The most likely proximate mechanism for seasonality of births in tamarins is photo-period, given existing data on populations living in natural and artificial lighting.

Demography and Dispersal Patterns of a Tamarin Population: Possible Causes of Delayed Breeding

We analyze the demography and dispersal patterns of a population of wild saddle-back tamarins (Saguinus fuscicollis) in Peru. Saddle-back tamarins live in small groups with one reproductive female and one or two breeding males. Data on the ages at which females had their first young and the ages at which males and females emigrated from their natal territories show that most animals do not first breed for at least one year past the age of potential sexual maturity. Data on the survival of adults and the lengths of tenure of breeders suggest that breeding vacancies are not frequent. Emigration and survival patterns are not significantly different for the two sexes. We suggest that delayed first breeding may occur in this species for any or all of the following reasons: a shortage of breeding positions, territories, or helpers; the risks of solitary dispersal; and the inclusive-fitness benefits gained from helping. We compare the demographic patterns of S. fuscicollis with those of well-studied cooperatively breeding species and suggest that two preconditions of helping behavior, high costs of infant care and frequent delayed breeding, are quite similar in cooperatively breeding birds and tamarins.

Facultative polyandry and the role of infant-carrying in wild saddle-back tamarins (Saguinus fuscicollis)

Wild saddle-back tamarins (Saguinus fuscicollis) in southeastern Peru have a variable mating system that can differ both between territories at any one time and within territories over time. Groups are usually monogamous or cooperatively polyandrous, but are occasionally even polygynous. This study addressed the following questions: why does this population contain both monogamous and polyandrous groups simultaneously? What factors determine whether specific groups are monogamous or polyandrous? The data from this study population tentatively support the hypothesis that adults should mate monogramously only if they have nonreproductive helpers (usually older offspring) to help rear infants. Without helpers, the reproductive success of both males and females is hypothesized to be higher, on average, if they mate polyandrously than if they mate monogamously. The proposed benefits of polyandry to males and females differ quantitatively, but in both cases benefits stem from the help that males provide in rearing young. The following results support this hypothesis. (1) Lone pairs were never seen to attempt breeding, and calculations suggest that the costs of lactation and infant-carrying are too great for lone pairs to have a high probability of being able to raise twin offspring (the normal litter size). (2) Polyandrous males and nonreproductive offspring contributed substantially to infant care, particularly infant-carrying (fig. 2). (3) Adult males carried infants approximately twice as often as did lactating females, presumably because of the combined costs of (a) lactation (Fig. 3) and (b) infant-carrying (Fig. 4). The proximate causes of cooperative polyandry inS. fuscicollis appear to be different from those responsible in several bird species, showing that cooperative polyandry is a complex phenomenon.