Reproduction of wild-caught marmosets (Saguinus labiatus labiatus) under laboratory conditions.

The reproductive performance of marmosets (Saguinus labiatus labiatus) was evaluated under laboratory conditions. Nineteen of 22 (86%) male-female pairs produced 32 live births during the first 18 months in the laboratory. The reproductive performance and survival rates were comparable to those of other Saguinus species maintained under similar conditions.     

Opportunistic Pneumocystis carinii infection in red-bellied tamarins (Saguinus labiatus).

P. carinii infection in red-bellied tamarins (Saguinus labiatus), born and maintained in a laboratory breeding colony, was examined by histopathologic examination postmortem. P. carinii cysts were detected in 6 of 10 red-bellied tamarins examined, by using Grocott's, toluidine blue O and immunostaining with avidin-biotin complex using antisera for rat-, simian-, and human-P. carinii. The results obtained from the present studies imply that P. carinii may be an important pathogen in this species.     

Hepatic multiple myelolipoma with severe coelomic edema in a red-bellied tamarin (Saguinus labiatus)

This report describes hepatic multiple myelolipoma with severe coelomic edema in a 14-year-old, male red-bellied tamarin (Saguinus labiatus). Multiple small and large nodules were formed in all lobes of the liver. Histopathologically, the nodules comprised mature and normal adipocytes and hematopoietic elements at various ratios that were composed of granulocytic, erythrocytic, and megakaryocytic series in various phases of maturation. All nodules were encapsulated and demarcated hepatocytes around masses. Myelolipoma in the liver is rare, and there are no reports of any cases to date. To our knowledge, this is the first report of hepatic multiple myelolipoma in a red-bellied tamarin.     

Haematological, coagulation and blood chemistry data in red-bellied tamarins Saguinus labiatus

Haematology, coagulation and clinical chemistry data are reported for a group of male and female red-bellied tamarins (Saguinus labiatus). The tamarins were juvenile and young adults and were bred in captivity. High mean values for activities of alkaline phosphatase, alanine amino-transferase, aspartate aminotransferase and creatine kinase were noted. The findings are compared with data obtained from other members of the family Callitrichidae.     

A case study employing operant conditioning to reduce stress of capture for red-bellied tamarins (Saguinus labiatus)

Traditional techniques used to capture New World monkeys, such as net capture, can induce high levels of acute stress detrimental to welfare. Alternatively, training nonhuman animals via operant conditioning to voluntarily participate in husbandry and/or veterinary practices is accepted as a humane process that can reduce stress and improve welfare. This study details the use of operant conditioning using positive reinforcement training (PRT) and target training to train a family of 5 captive red-bellied tamarins (Saguinus labiatus) in a wildlife park to voluntarily enter a transportation box and remain calm for 1 min after 54 training sessions. Observations of 2 unrelated net-capture processes provided measures of locomotion and vocalizations as indicators of stress behavior that were compared with those of the trained tamarins. Net-captured monkeys exhibited rapid erratic locomotion and emitted long, high-frequency vocalizations during capture whereas the trained tamarins exhibited minimal locomotion and emitted only 4 brief vocalizations (root mean square 35 dB) during capture. This indicates that the use of PRT considerably reduced potential for stress and improved welfare during the capture and containment of the tamarins.     

An outbreak of Yersinia pseudotuberculosis infection in a small indoor breeding colony of red-bellied (Saguinus labiatus) tamarins

A spontaneous outbreak of yersiniosis caused by Yersinia pseudotuberculosis serotype IIB occurred in a small indoor breeding colony of red-bellied tamarins (Saguinus labiatus) during the winter of 1981. Of 35 monkeys at risk 6 died of an acute or subacute infection over a period of 23 days. Clinical signs were anorexia, weakness, listlessness and depression. The disease was characterized by focal necrosis of the liver, spleen, mesenteric lymph nodes, ulcerative enteritis, and the presence of colonies of Gram-negative bacilli in the lesions. Y. pseudotuberculosis was isolated from the liver, spleen, mesenteric lymph nodes and kidney but not from the blood, lung or intestine. Contaminated food was believed to be the source of infection.     

Vigilance,vocalizations, and cryptic behavior at retirement in captive groups of red-bellied tamarins (Saguinus labiatus)

Frequent references are made to presumed antipredator adaptations exhibited by callitrichids, but there are very few systematic investigations of these behaviors. One set of untested presumptions stems from observations that callitrichids become especially vigilant and cryptic prior to retirement each evening. This hypothesis was tested in the current study by quantifying the rates of vocalizations and extragroup behavior at various times of the day. Using two groups of captive red-bellied tamarins, it was demonstrated that these primates do become relatively more quiet and more attentive to the nonsocial environment prior to retirement each evening, culminating in virtual silence once the nest box has been entered. While the adaptive significance of these phenomena has not yet been tested, it is likely that the behaviors reduce vulnerability to predation.     

A field study on the red-bellied tamarin,Saguinus l. labiatus,in Bolivia

A 5-month field study was conducted on red-bellied tamarins,Saguinus labiatus labiatus, in the Pando Department of northern Bolivia. Group sizes ranged from 5 to 10 animals, and each group associated with a group of saddle-backed tamarins,Saguinus fuscicollis weddelli. Members of three groups were trapped and marked and data were collected by radiolocation. The average range size used over 10 days was 19 ha. On average the groups entered about 29% of their range each day and had a mean daily path length of about 1487 m. The groups used a number of different sleeping sites within their ranges. They fed on a variety of different fruits and also on nectar from flowers, resin, and insects. Areas within the home range which were used significantly more than expected were generally those in which one or more of the following existed: a sleeping site, an intergroup encounter site, or a site where the group took shelter during an extended period of heavy rain.     

Non-random association of opsin alleles in wild groups of red-bellied tamarins (Saguinus labiatus) and maintenance of the colour vision polymorphism

The remarkable X-linked colour vision polymorphism observed in many New World primates is thought to be maintained by balancing selection. Behavioural tests support a hypothesis of heterozygote advantage, as heterozygous females (with trichromatic vision) exhibit foraging benefits over homozygous females and males (with dichromatic vision) when detecting ripe fruit on a background of leaves. Whilst most studies to date have examined the functional relevance of polymorphic colour vision in the context of foraging behaviour, alternative hypotheses proposed to explain the polymorphism have remained unexplored. In this study we examine colour vision polymorphism, social group composition and breeding success in wild red-bellied tamarins Saguinus labiatus. We find that the association of males and females within tamarin social groups is non-random with respect to colour vision genotype, with identified mating partners having the greatest allelic diversity. The observed distribution of alleles may be driven by inbreeding avoidance and implies an important new mechanism for maintaining colour vision polymorphism. This study also provides the first preliminary evidence that wild trichromatic females may have increased fitness compared with dichromatic counterparts, as measured by breeding success and longevity.     

The Perception of Sex-specificity in Long Calls of the Tamarin (Saguinus labiatus labiatus)

Long calls given by red-chested moustached tamarins (Saguinus l. labiatus), typically 1–2 s in duration and made up of individual syllables, reveal distinctive sex-specificity as well as population and individual differences in their acoustic structure. Distributions of male calls and female vocalizations are discrete with regard to two acoustic parameters, i.e. number of syllables and mean inter-syllable intervals. Mean number of syllables produced in a given time is much greater in male than in female calls. I played back synthetic versions of the long calls varying in mean inter-syllable intervals to captive tamarins and found that the sex differences were encoded in a relatively simple acoustic form. The tamarin is able to identify the sex of unfamiliar calling conspecifics by voice alone.     

Sleeping Site Selection by Captive Tamarins (Saguinus labiatus)

We investigated the sleeping site preferences of three captive groups of red-bellied tamarins (Saguinus labiatus), especially as those preferences might relate to protection and safety. The tamarins chose sleeping boxes that offered the most concealment, the greatest distance from the floor, and the greatest cover overhead. They did not, however, avoid sleeping boxes that were attached to the floor via vines. When the tamarins had no choice but to sleep in a box that offered little in the way of concealment, they increased their rates of vigilant scanning. Whereas a number of considerations other than those related to predation pressures must also affect sleeping site choices, we have demonstrated that, under controlled circumstances, these primates choose to sleep in locations in which they are hidden and inaccessible.     

Vigilance in Single- and Mixed-Species Groups of Tamarins (Saguinus labiatus and Saguinus fuscicollis)

By forming larger sizes of groups, individuals benefit from a decrease in vigilance, but the collective vigilance of the group as a whole is not compromised. We examined whether this group size effect is apparent in mixed-species groups of red-bellied tamarins (S. labiatus) and saddleback tamarins (S. fuscicollis) which form stable and permanent associations in the wild. We studied general vigilance and responses to hidden threatening stimuli in five captive groups of each species, while they were housed in single- and mixed-species groups. For vigilance, the individual rate was lower in the larger mixed-species groups than in the smaller single-species groups. In addition, the amount of time when at least one individual was vigilant was higher in mixed-species groups. This suggests that the tamarins alter their vigilance behavior in the presence of the other species. In response to hidden threats, both species performed brief vigilance checks and frequencies of checking did not differ in single- and mixed-species groups. However, both species had a significant reduction in the mean duration per check, and there was a reduced total amount of time spent vigilance checking in the mixed-species groups compared to the single-species groups, demonstrating the group size effect. Overall the mixed-species groups had a higher number and mean duration of checking than the smaller single-species groups. Given that the two species share a common set of predators, and respond to each other's alarm calls, these findings provide strong evidence that individuals of both tamarin species may be able to benefit from forming mixed-species groups via improved vigilance and monitoring of threats.     

Visual monitoring of threatening objects by captive tamarins (Saguinus labiatus)

Captive social groups of red-bellied tamarins (Saguinus labiatus) were observed in the presence of threatening, inanimate objects. The tamarins monitored the stimuli over the course of the 20-minute trials by conducting brief, periodic visual checks of the objects. The average number of checks per subject per trial was stable both across trials and between groups, and individual differences in rates varied relatively little around the group means. These data generate the hypothesis that there is a species-typical execution of vigilance in the presence of mildly threatening objects. This execution takes the form of brief visual inspections of the stimulus, usually by one tamarin at a time, at a fairly consistent rate. The discussion of the data takes place in the context of the behavioral ecology of callitrichid species.     

Locale-specific Vocal Behaviour of the Tamarin (Saguinus I. labiatus)

A quantitative acoustic analysis of long calls of red-chested moustached tamarins (Saguinus l. labiatus) was undertaken after capture in the primary forest of Northwestern Bolivia, comparing two populations. Two acoustic parameters are statistically significantly different. Acoustic properties distinguishing individual heterogeneity are quite consistent between the groups and completely different from cues separating population variability. As these two study groups were only 27 km apart when trapped, and as no geographical barriers prevented genetic exchanges between them, we assume populational vocal variability comparable to dialects in birds.     

Red-bellied tamarins (Saguinus labiatus): Hematologic reference values and hemopathologic responses

Hematologic reference values have been established for captive adult red-bellied tamarins (Saguinus labiatus) by carrying out full blood counts and fibrinogen estimations on 25 clinically normal animals. The only significant sex difference detected was in the reticulocyte count which was higher in females than in males. The reference values were used to identify abnormal changes in the blood of nine clinical cases. Hypochromic anemia, neutrophilia, and raised fibrinogen levels were found in animals with self-inflicted injuries, dermatitis, and ileocecal intussusception. Target cells and jaundiced plasma were noted in a case of yersiniosis. Two animals in which generalized muscle wasting was the main abnormal clinical sign were severely anemic, and in one of these cases a significant number of Heinz bodies was present. The findings in these two animals were compared with those in common marmosets (Callithrix jacchus) with possible wasting marmoset syndrome.     

Spontaneous occurrence of Angiostrongylus costaricensis in marmosets (Saguinus mystax)

Two marmosets imported from Iquitos, Peru, were found to be infected with Angiostrongylus costaricensis. Both animals had large solitary granulomas involving the wall and adjacent mesentery of the small intestine. Histopathologic examination showed the adult nematodes in the lumina of the mesenteric arteries that coursed through these granulomas. The inflammatory reaction was associated with numerous degenerating eggs and larvae. This is the first report of this parasite in nonhuman primates and extends its geographic range to Peru. In addition, in one animal, Dipetalonema sp were seen free in the abdominal cavity, and pleroceroid larvae (spargana) were in the loose connective tissue of the left axilla. This animal also had microgranulomas associated with eggs and larvae of Angiostrongylus in the kidney, liver, lung, and heart.