Reactions of wild tamarins,Saguinus mystax andSaguinus fuscicollis to avian predators

During a field study in northeastern Peru, the reactions of a group ofSaguinus mystax on Padre Isla and of a mixed-species troop ofS. mystax andSaguinus fuscicollis at the Río Blanco to raptorial and other birds were observed. Alarms that are specific to flying stimuli were elicited by birds of prey, but other birds that do not represent a threat to the tamarins also caused alarm calls. Alarm events (i.e., instances when one or more alarm calls were given) were observed at rates of 0.3/hr (Padre Isla) and 0.5/hr (Río Blanco). Rates of alarm events significantly increased after the birth of an infant in the Padre Isla group and after the attack of an ornate hawk-eagle (Spizaetus ornatus) on the Río Blanco group. Reactions to alarming stimuli/alarm calls ranged from looking up to falling down from trees. The modification of the tamarins' behavior by the potential presence of aerial predators indicates that raptors represent an important predatory threat to tamarins.     

Vertebrate predation by sympatric tamarins, Saguinus mystax and Saguinus fuscicollis

Vertebrate predation was examined in sympatric moustached tamarins (Saguinus mystax) and saddle-back tamarins (Saguinus fuscicollis) in the Amazon rainforest of northeastern Peru. Both species prey on frogs and lizards, and very rarely on nestling birds. As a result of divergent foraging strategies, S. mystax primarily exploited frogs at higher strata of the forest, while S. fuscicollis predominantly preyed on reptiles in the lower strata and on the ground. This difference may strengthen the niche differentiation between these two tamarin species that exists with regard to other prey.     

Field observations on scent-marking behaviour in saddle-back tamarins, Saguinus fuscicollis (Callitrichidae, Primates)

The scent-marking behaviour of a group of six saddle-back tamarins, Saguinus fuscicollis nigrifrons , was studied in the Amazon rain forest of north-eastern Peru. Three types of scent marking were recognized: anogenital marking, suprapubic marking and sternal marking. Anogenital marking was the most frequent type. Two or more scent-marking acts of the same or different type were generally combined into sequences. Most scent-marking was performed on branches and lianas; trunks were infrequently used. The tamarins mainly marked on horizontal or inclined substrata with diameters between 3 and 10 cm and a height between I and 10 m. The temporal distribution of scent-marking exhibited a maximum in the early morning between 06:00 and 07:00h and a minimum between 16:00 and 17:00h. The majority of scent-marking occurred in the peripheral areas of the home-range. The spatial distribution of scent-marking was correlated with the intensity of home-range use. No elevated frequencies of scent-marking were observed during intergroup encounters. The results of this field study are compared with findings from laboratory studies, and hypotheses concerning the function of scent-marking are discussed.     

Urine washing and related behaviour in wild moustached tamarins,Saguinus mystax (callitrichidae)

Urine washing (UW) and urinating onto hand (UH) are reported for the first time for a wild callitrichid monkey, the moustached tamarin,Saguinus mystax. Both patterns are very rare and no sex difference in frequency is apparent. The temporal distribution shows a maximum of UH/UW around midday when ambient temperature is at maximum and humidity at minimum. No seasonal effects were observed, but any seasonal effect might be masked by the low frequency of UH/UW. UH/UW are not linked to a single behavioural context and may have multiple functions in thermoregulation/water conservation, cleaning, improving grip, and as a social signal.     

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.     

Seed dispersal by sympatric tamarins,Saguinus mystax and Saguinus fuscicollis: diversity and characteristics of plant species

In a comparative study of Saguinus mystax and Saguinus fuscicollis, we examined the spectrum of plant species whose seeds are dispersed by these two tamarin species. We characterize these plants in terms of life form, fruit colour, pulp consistency and seed dimensions. The tamarins disperse a much broader spectrum of plant species than previously reported (88 of the total of 155 species exploited for fruit). While the distribution over plant life form, fruit colour and pulp consistency is identical between dispersed plant species and the overall spectrum of consumed plant species, clear differences exist in all seed parameters (length, width, height, volume, mass) except specific weight between dispersed and non-dispersed plant species for both tamarin species. Plant and fruit characteristics and seed parameters of dispersed plant species do not differ between S. mystax and S. fuscicollis, suggesting that their ecological and evolutionary interaction with plants is very similar or identical.     

The impact of cropping on wild populations of Saguinus mystax and Saguinus fuscicollis in Peru

A transect census technique was used to estimate the population densities of Saguinus mystax and Saguinus fuscicollis at two sites in Peru. Cropping of these two species had occurred five years before the census at one site and two years before at the other. The populations of S. mystax at both sites had recovered completely from cropping, and the relationship between S. mystax and S. fuscicollis had not been altered at one site and had been reversed in favor of S. mystax at the other.     

Prey foraging of red titi monkeys, Callicebus cupreus, in comparison to sympatric tamarins, Saguinus mystax and Saguinus fuscicollis

We compared the prey capture strategies of red titi monkeys, Callicebus cupreus, with those of sympatric mustached, Saguinus mystax, and saddleback tamarins, Saguinus fuscicollis, to examine whether animal prey is important in niche differentiation between these Neotropical primates. We collected data on strata and substrate use during foraging, on prey searching and capturing, and on prey type of two C. cupreus groups and one group each of S. mystax and S. fuscicollis during a 5-month field study in northeastern Peruvian Amazonia. Our results showed that C. cupreus differed both from S. mystax and S. fuscicollis in prey capture strategies: (1) C. cupreus used lower forest strata for prey search and capture than S. mystax and higher forest strata than S. fuscicollis. (2) C. cupreus captured prey on a higher variety of substrates than S. mystax and more often on open microhabitats compared to S. fuscicollis. (3) C. cupreus captured prey more often directly than S. mystax and rarely by manual search, in contrast to S. fuscicollis. (4) C. cupreus fed exclusively on arthropods and focused on Hymenoptera, in contrast to both tamarin species that focused on Orthoptera and included vertebrates in their diet. These findings indicate that animal prey plays a role in niche differentiation between C. cupreus and S. fuscicollis/S. mystax and might facilitate the coexistence of these three sympatric species.     

Sleeping habits of tamarins, Saguinus mystax and Saguinus fuscicollis (Mammalia; Primates; Callitrichidae), in north-eastern Peru

The sleeping habits of moustached tamarins, Saguinus mystax , and saddle-back tamarins, Saguinus fuscicollis , were studied in northeastern Peru. Five types of sleeping sites were distinguished: 1) Jessenia bataua palms; 2) tree hollows; 3) dense tangles of vegetation; 4) crotches; 5) open horizontal branches. Both tamarin species used Jesseniu-palms most frequently. Tree hollows ranked second in the saddle-back tamarins, but were never used by moustached tamarins. Sleeping sites of moustached tamarins were located significantly higher than those of saddle-back tamarins. Jessenia -palms used by moustached tamarins were significantly higher than palms from a random transect sample, but this was not the case for Jessenia -palms used by saddle-back tamarins. For both species, concealment seems to be more important than height above ground. The maximum number of subsequent nights spent in the same sleeping site was two in moustached tamarins and six in saddle-back tamarins. The two tamarin species did not compete for sleeping sites. While the general pattern of sleeping site selection conforms to hypotheses predicting safety from predators as a major factor, differences between the two tamarin species reflect general niche differences between them. Most sleeping sites are located in exclusively used parts of the home range. Moustached tamarins generally use sleeping sites that are close to the last feeding site of the afternoon. The distance between simultaneously used sleeping sites of moustached and saddle-back tamarins are generally close together, which helps to minimize time spent out of interspecific association.     

Body weights in mixed species troops of Saguinus mystax mystax and Saguinus fuscicollis nigrifrons in Amazonian Peru

An investigation of body weights of members of mixed species troops of Saguinus mystax mystax and Saguinus fuscicollis nigrifrons was conducted at the Rio Blanco Research Station in northeastern Peru. A total of 107 adult and subadult tamarin monkeys were trapped, measured, and released. Data collected indicate that mean body weights for adult male and female moustached tamarins are 564 gm and 626 gm, respectively, whereas for adult saddle-back tamarins these values are 412 gm and 411 gm. Subadults weighed 11-27% less than adults. Body weights recorded in this study are significantly greater than those previously reported for tamarins of the same species and age living in other areas of Amazonian Peru. We hypothesize that, in the case of moustached and saddle-back tamarins, advantages associated with feeding and foraging in mixed species troops facilitate greater efficiency in resource monitoring and result in the maintenance of larger body weights.     

Behavioural observations on captive pairs of wild caught tamarins (Saguinus mystax)

Quantitative data are given on 12 categories of behaviour, including scent marking, allogrooming, huddling, and proximity for individual tamarins within 14 male, female pairs and the mated pair of one family group of four animlals. Time sample data were recorded at 30 sec intervals to a total of 260 hr. In addition, some data were collected from within time sample intervals. Individual and intergroup variation in behaviour was a main finding of the study. It was found, however, that females scent marked significantly more than males, at least on the basis of their total marking frequencies, that females tended to groom males more than vice versa, and that although the general proportions of activities were similar in two conditions of housing, their spatial distribution was different under the two conditions. There was very little overt aggression among the pairs.     

Role of spatial memory in primate foraging patterns: Saguinus mystax and Saguinus fuscicollis

From field data collected in the Amazon Basin of northeastern Peru, I present evidence that moustached (Saguinus mystax) and saddle-back (Saguinus fuscicollis) tamarins maintain detailed knowledge of the distribution and location of many tree species in their home range. During the wet season months of October through December 1984, fruits and exudates from 20 tree species and over 150 individual trees accounted for 75% of plant feeding time. These trees exhibited a patchy distribution; mean nearest-neighbor distances between trees of the same species averaged 148 meters. Moustached and saddle-back tamarins visited an average of 13 trees per day, concentrating their feeding efforts on 4–11 individual trees from a small number of target species. In 70% of all cases the nearest tree of a given species was selected as the next feeding site. Movement between these sites was characterized by relatively straight-line travel. It is argued that S. mystax and S. fuscicollis offset the patchiness component of the fruit and exudate part of their diet through goal-directed foraging and an ability to compare accurately the distances and directions from their present location to a large number of potential feeding trees.     

Pathology of captive moustached tamarins (Saguinus mystax)

The pathology of 33 moustached tamarins (Saguinus mystax) previously used in hepatitis A and GB virus studies is reported. Chronic lesions in colon, heart, and kidney were common in the monkeys and appeared not to be due to the experimental exposures. Colitis cystica profunda (CCP), a disease that affects humans and is characterized by the presence of mucin-filled epithelial downgrowths and cysts in the colonic submucosa, was found in 24 of the 33 (72.7%) tamarins. Interstitial myocardial fibrosis was present in 22 (66.6%) animals, and various degrees of membranoproliferative glomerulonephritis occurred in 28 (84.8%) monkeys. In addition, 28 (84.8%) tamarins demonstrated diffuse hepatocellular vacuolation with mild lymphoplasmacytic infiltrates, possibly as a result of the experimental infections, and peliosis hepatis occurred in 7 (21.2%) animals. The etiology of CCP is unknown, and no reliable animal models are available because most cases in animals are reported only sporadically. Myocardial fibrosis in tamarins has not been reported previously, and all current animal models require experimental manipulation of the animal to mimic the human disease. The results from this study suggest that captive S. mystax has high incidence of spontaneous CCP, myocardial fibrosis, and membranoproliferative glomerulonephritis. This species may be a spontaneous animal model for pathogenesis and experimental therapy studies of the analogous human diseases.     

Spatial patterns of scent marking in wild moustached tamarins, Saguinus mystax: no evidence for a territorial function

I investigated whether scent marking has a territorial function in wild moustached tamarins. I examined the spatial distribution of scent marking within the home ranges of four groups of this neotropical primate and tested predictions from Gorman & Mills' (1984, Journal of Zoology,202, 535-547) model for border and 'hinterland' marking. Although home ranges were economically defensible, no evidence was found for increased marking along the territorial boundary or in areas of home range overlap, but there was also no evidence for hinterland marking. Observed distributions of scent marking in exclusively used and overlapping areas of the home range did not deviate from distributions that would be expected if scent marking occurred at random (expectation based both on size of area and on frequency of quadrat occupation), and there was a strong correlation between frequency of quadrat occupation and frequency of scent marking per quadrat. These results indicate that scent marking has no territorial function in moustached tamarins. This is in line with mainly qualitative findings from the majority of other studies on wild marmosets and tamarins. These and other findings on scent marking in moustached tamarins suggest that this behaviour functions mainly in intersexual communication. Copyright 2000 The Association for the Study of Animal Behaviour.     

Diet and feeding ecology of saddle-back (Saguinus fuscicollis) and moustached (S. mystax) tamarins in an Amazonian terra firme forest

The feeding ecology of two small-bodied primate species—saddle-back ( Saguinus fuscicollis auilapiresi ) and moustached tamarins ( S. mystax pileatus )—occurring in stable, mixed-species groups was studied in a terra firme forest site in the upper Urucu River, Amazonas, Brazil. Ecological data are based primarily on one mixed-species group of 5–8 saddle-back and 8–10 moustached tamarins. The overall vegetative and animal-prey components of each tamarin species' diet, their selection of food species, and the seasonal variation in their use of plant resources are described, and compared to those of callitrichids elsewhere. The extremely diverse diet of tamarins included at least 136 tree, 33 vine and liana, 12 epiphyte and nine shrub species, as well as a wide range of prey items. They fed primarily on ripe fruit pulp of most of these species for most of the year, but shifted to floral nectar and plant exudates of a few key plant species during the dry season. Taxonomic overlap in plant diet was nearly complete between the two tamarin species, but they diverged considerably in their prey capture techniques. Saddle-backs used the low forest understorey, and manipulatively searched for sedentary prey concealed within discrete, usually rigid, microhabitats, whereas moustached tamarins used the midstorey where they visually searched for mobile prey well exposed on foliage. These and other feeding and foraging patterns are discussed in the light of other callitrichid species studied to date.