Predation on Orthoptera and other orders in insects by tamarin monkeys, Saguinus mystax mystax and Saguinus fuscicollis nigrifrons (Primates: Callitrichidae), in north-eastern Peru

Kaytydids and related insects are an important component in the diets of moustached ( Saguinus mystax mystax ) and saddle-back tamarins ( Saguinus fuscicollis nigrifrons ). Based on preliminary data of captured prey, trends suggest that partitioning occurs regarding orthopterans as a limited food resource. Of species caputre as prey, only three were shared by both tamarin species. Saddle-back tamarins appeared to specialize more on understorey species (0-4 m), concentrating on pseudophylline katydids. Moustached tamarins incorporated a greater percentage of phaneropterine katydids from the lower to middle canopy into their diet of insects. Although most prey species were exposed to view during the diurnal feeding period of the tamarins, only the saddle-back tamarin fed on katydids that spend the day concealed from view within dead curled leaves. Differentiation of the prey spectrum may represent a critical pattern of niche differentiation in these two sympatric tamarin species, which show a high overlap in their plant food resources.     

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.     

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.     

Sperm parameters and testicular volumes in Saguinus mystax

Adult male Saguinus mystax tamarins were evaluated for sperm parameters and testicular volumes. Sperm concentrations average 195.5 X 10(6)/cc with 41.7% motile sperm. Semen specimens were classified as normal, relative to sperm morphology, when 95% or more of the sperm in the specimen had normal morphology; 76% of the animals evaluated had normal semen specimens using this criterion. Testicular volumes averaged 726.9 mm3. A total of 50 infants were sired by 16 of these males during the period covered by this report.     

Trichobezoars in two saddleback tamarins (Saguinus fuscicollis)

Two captive-born Saddleback tamarins (Saguinus fuscicollis) died unexpectedly in the primate colony at the Peruvian Primatological Project. At necropsy, a firm, mobile, oblong, obscure mass was discovered in the stomach of each. They were removed and determined to be trichobezoars.     

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.     

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.     

The ecology of seed dispersal in two species of callitrichid primates (Saguinus mystax and Saguinus fuscicollis)

Data collected during a 12-month field investigation of mixed species troops of Saguinus mystax and Saguinus fuscicollis in the Amazon Basin of north-eastern Peru indicate that callitrichid primates play an important role in tropical forest seed dispersal. Moustached and saddle-back tamarins were observed to ingest seeds from a variety of tree and liana species and pass them unharmed. These seeds tended to be large and heavy, and passed through the tamarin digestive tract in one to three hours. Experimental plantings of defecated seeds yielded a germination success rate of 70%. The specific gravity of these seeds (weight/volume) was inversely correlated with passage time and apparently had an indirect influence on the distance that seeds were dispersed from the parent tree. In the case of three preferred fruiting species, Leonia glycycarpa, Pourouma sp., and Hippocrateaceae #283, the present distribution of adult trees closely resembled the pattern of the seed shadow created by Saguinus. Moustached and saddle-back tamarins appeared to be reliable and high-quality dispersal agents for a number of tree and liana species. In this role, they are likely to exert an important influence on the composition, distribution, and regeneration patterns of Amazonian rain forest.     

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.     

An ecological comparison of two sympatric primates:Saguinus fuscicollis andCallicebus moloch of Amazonian Peru

The ecologies of two sympatric primates,Saguinus fuscicollis andCallicebus moloch, were compared during a four-month field study in southeastern Peru in order to examine the mechanisms by which these primate frugivores minimize competition for food and space.Saguinus fuscicollis andCallicebus moloch were found to differ dramatically both in diet and in use of the shared habitat. Specifically, tamarins and titis showed very little overlap in their choices of food plants or animal foods and they used distinctive foraging styles, exploiting very different parts of the habitat for animal prey. Significant interspecific differences were found in the use of particular support structures and strata within the forest, and in the density of vegetation preferred. These results suggest that resource competition between saddle-backed tamarins and dusky titis is minimal, a fact that could account for the high frequency of free association between the two species and the benign nature of these interspecific contacts.     

Interspecific variation of scent-marking behaviour in wild tamarins, Saguinus mystax and Saguinus fuscicollis.

The scent-marking behaviour of sympatric moustached, Saguinus mystax, and saddle-back tamarins, Saguinus fuscicollis, was compared in order to explore interspecific differences and potential sources of variation. The author examined basic patterns of scent marking (types, intensity, complexity), substrate use (type, orientation, height), and social patterning of scent marking in three groups of S. mystax and one group of S. fuscicollis at the Estación Biológica Quebrada Blanco, Peruvian Amazonia. S. mystax and S. fuscicollis differed significantly in the relative frequency of different types, and in the intensity and complexity of scent marking. Only S. fuscicollis showed allomarking. They also differed significantly in the type, orientation and height of substrates used for scent marking which corresponded to general differences in substrate use. In S. fuscicollis, but very rarely in S. mystax, two or more group members marked the same site sequentially or simultaneously. 'Collective scent marking', i.e. simultaneous scent marking by most or all group members, occurred only in S. fuscicollis. Since both tamarin species live sympatrically in mixed-species groups, ecological factors are unlikely to account for the differences found in scent-marking behaviour (except for differences in substrate use). They probably relate to as yet unknown differences in social and reproductive strategies of the two species.     

Spontaneous pathology of the common marmoset (Callithrix jacchus) and tamarins (Saguinus oedipus, Saguinus mystax)

Background  Marmosets and tamarins are increasingly used in research, but their pathology remains poorly defined compared with Old World primates.

Methods  Necropsy records of 129 marmosets and 52 tamarins were reviewed; none was used experimentally.

Results  The most common marmoset lesions were dehydration, emaciation, nephritis, colitis, and inanition. The most common tamarin lesions were dehydration, ascites, emaciation, and congestive heart failure. Colitis and heart disease were the most common cause of death in marmosets and tamarins, respectively. Immature marmoset and tamarin deaths often occurred within the first month of life. Immature marmosets usually died from inanition, stillbirth, and colitis; immature tamarins from atelectasis, stillbirth, heart failure, and colitis. Lymphoma was the most common neoplasm for both marmosets and tamarins.

Conclusion  The findings were similar to prior reports with differences in frequency and severity. We report the first case of endometriosis in a marmoset.     

Reproduction of wild-caught tamarins (Saguinus mystax mystax) under laboratory conditions

The reproductive performance of tamarins (Saguinus mystax mystax) under laboratory conditions was evaluated. Fifteen of 20 male-female pairs were fertile and produced 30 live births during an observation period of 3.5 years. Twenty-six breeders (65%) and 12 offspring (40%) more than 3 years old were alive at the termination of the reporting period.     

Subspecific genetic differences in the saddle-back tamarin (Saguinus fuscicollis) postcranial skeleton

Saddle-back tamarins (Saguinus fuscicollis) have been differentiated into subspecies based on coat color and facial morphology. Morphology of first-generation genetic hybrids can provide an understanding of population differences and evolution that may otherwise be difficult to obtain. This study compares postcranial morphology in two hybrids of saddle-back tamarins (S. f. illigeri x S. f. lagonotus and S. f. illigeri x S. f. leucogenys) to the purebred subspecies. We examine whether postcranial morphology differs between the purebred subspecies and their hybrids, and whether hybrids exhibit heterosis indicative of genetic differences between the parental subspecies. Fifty postcranial dimensions, or traits, were measured on 287 S. fuscicollis skeletons. Measurements were corrected for sex differences and environmental differences (wild-derived or laboratory-born). Females were larger than males for most postcranial dimensions, especially in the pelvis. Significant environmental differences were found throughout the postcranial skeleton, with wild-derived animals generally larger than animals born in the laboratory. Significant heterosis was found for six postcranial traits in the S. f. illigeri x S. f. leucogenys cross, and heterosis was found for 15 postcranial traits in the S. f. illigeri x S. f. lagonotus cross. These results suggest that subspecies differences in skeletal morphology are generally due to genetic rather than environmental differences. The subspecies appear to represent geographic isolates that differ in gene frequencies and directional dominance for skeletal traits.     

Field observation of snake-mobbing in a group of saddle-back tamarins, Saguinus fuscicollis nigrifrons

At the Rio Blanco in Northeastern Peru a group of 6 saddle-back tamarins was observed to mob two Corallus enydris snakes which were hanging from a liana. These and other observations of snake-mobbing demonstrate that callitricids exhibit a special behaviour against potential predators, which is very similar to the mobbing displays of birds and other mammals. It is suggested that the adaptive significance of snake-mobbing in tamarins lies in the cultural transmission of information about potential predators.     

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.     

Seasonal Variation in Polyspecific Associations Among Callimico goeldii, Saguinus labiatus, and S. fuscicollis in Acre, Brazil

Polyspecific associations (PSA) occur when 2 or more species maintain proximity or coordinate activities. PSA may provide ecological benefits similar to those of monospecific groups, i.e., protection against predation and improved foraging efficiency, but may also impart costs, such as feeding competition. I studied 3 New World Callitrichidae—Callimico goeldii, Saguinus fuscicollis, and S. labiatus—in northwestern Brazil over 18 mo between April 1999 and August 2003, during which single primary study groups of C. goeldii, S. labiatus, and S. fuscicollis consistently associated with one another. I compared patterns of PSA participation to variation in plant diets during wet and dry seasons. All 3 species associated an average 61% of observation time, but with significant seasonal variation in PSA. During the dry season, April–September, PSA occurred significantly less frequently than during the wet season, October–March (37% vs. 88%). The variation in PSA corresponded with seasonal shifts in plant food diets, resulting in less dietary overlap among all 3 species during the dry season, particularly between Callimico goeldii and Saguinus labiatus. Dietary richness, diversity, and evenness were also lower in the dry compared to the wet season for each species. The results suggest a link between PSA participation and diet among the taxa; foraging-related costs or feeding competition may constrain PSA during the dry season.     

Functionally Referential Alarm Calls in Tamarins (Saguinus fuscicollis and Saguinus mystax) – Evidence from Playback Experiments

Studies on primate vocalisation have revealed different types of alarm call systems ranging from graded signals based on response urgency to functionally referential alarm calls that elicit predator‐specific reactions. In addition, alarm call systems that include both highly specific and other more unspecific calls have been reported. There has been consistent discussion on the possible factors leading to the evolution of different alarm call systems, among which is the need of qualitatively different escape strategies. We studied the alarm calls of free‐ranging saddleback and moustached tamarins (Saguinus fuscicollis and Saguinus mystax) in northeast Peru. Both species have predator‐specific alarm calls and show specific non‐vocal reactions. In response to aerial predators, they look upwards and quickly move downwards, while in response to terrestrial predators, they look downwards and sometimes approach the predator. We conducted playback experiments to test if the predator‐specific reactions could be elicited in the absence of the predator by the tamarins’ alarm calls alone. We found that in response to aerial alarm call playbacks the subjects looked significantly longer upwards, and in response to terrestrial alarm call playbacks they looked significantly longer downwards. Thus, the tamarins reacted as if external referents, i.e. information about the predator type or the appropriate reaction, were encoded in the acoustic features of the calls. In addition, we found no differences in the responses of S. fuscicollis and S. mystax whether the alarm call stimulus was produced by a conspecific or a heterospecific caller. Furthermore, it seems that S. fuscicollis terrestrial alarm calls were less specific than either S. mystax terrestrial predator alarms or either species’ aerial predator alarms, but because of the small sample size it is difficult to draw a final conclusion.