American Journal of Primatology最新文献

Capuchin monkeys are known for their object manipulation skills, but little is known about that in physically impaired individuals. Several wild populations use tools primarily for foraging, but such behavior is rarely reported for drinking water. In urban fragments, objects discarded are available for manipulation, and water can be scarce. Therefore, the study of object manipulation in such contexts illuminates how human-made artifacts and tools can be used to deal with anthropogenic opportunities and resource constraints. We investigated object manipulation and tool use in urban robust capuchin monkeys in Foz do Iguaçu, southern Brazil. We aimed to understand how much these animals invest their activities in object manipulation, the origin of the materials they use, the types of manipulations and tools employed, and whether the frequency of these behaviors differs among sex and age classes, as well as between dry and wet months. We described a new technique of tool use in capuchin monkeys, involving the use of containers to drink water, and a stronger tendency to use tools by an injured male juvenile with a hand deficiency. Over the course of 865 h of observation, we noted that tools were simple, infrequently used, and most were exhibited by juveniles, primarily by the injured individual, to access water during the driest periods. Containers to collect water emerged as the most frequent technique. Capuchins took advantage of human-made receptacles from nearby construction sites. Our findings contribute to understanding the flexibility of capuchins' tool use in response to urban novelties and pressures.

The responses of nonhuman primates towards conspecific deaths in the wild, and the activities of carnivores scavenging the corpses, are different but interconnected thanatological and ecological aspects of wildlife mortality. We report the first thanatological events observed in a wild, multilevel group of Myanmar or black snub-nosed monkeys (Rhinopithecus strykeri [R. strykeri]) and mesocarnivores scavenging on a monkey carcass in the Pianma region, near the China-Myanmar border. We detected two freshly deceased carcasses during field surveys. The group members visited the location of their recently deceased conspecific twice and variously looked down at the carcass, emitted alarm calls and unusual contact calls, hugged social partners and prevented approaches by individuals from other social units. These behaviors suggest strong bonds and emotional reactions to the death of a companion in R. strykeri. Infrared camera trapping revealed the Siberian weasel (Mustela sibirica) as the principal scavenger on the carcass, followed by the yellow-throated marten (Martes flavigula). Siberian weasels showed greater activity levels and time spent feeding on the R. strykeri carcass when it was fresh, while remaining vigilant for potential competitors and predators. After the carcass was largely consumed and decayed, both frequency and duration of feeding and vigilance behaviors decreased.

Indirect reciprocity consists of performing an act that benefits a recipient while increasing the chances of receiving cooperation from a bystander. While widespread in humans, evidence of indirect reciprocity in nonhuman animals is scarce. Indirect reciprocity may involve an audience effect if cooperation increases in the presence of an audience. We investigated indirect reciprocity and audience effects in wild Geoffroy's spider monkeys (Ateles geoffroyi). Using survival analysis, we assessed whether individuals who had recently groomed others tended to be groomed more by other group members (indirect reciprocity), and whether individuals tended to groom more when surrounded by bystanders (audience effect). We found no evidence for indirect reciprocity: individuals did not receive more grooming in the 10 min after they had recently groomed others. We also found that the presence of an audience did not increase the likelihood of grooming. Actually, male spider monkeys were less likely to groom one another in the presence of other males. We found no evidence for audience effects associated with the presence of adult males on the likelihood of grooming by subadult males. Our results suggest indirect reciprocity is absent in spider monkeys, at least in the 10-min timeframe we investigated, and contribute to the limited literature on indirect reciprocity in nonhuman animals.

Deforestation, habitat loss, and fragmentation impact the ecology, genetics, and health of many wildlife species, including primate populations. We evaluated the association between landscape characteristics and demographic features of Alouatta caraya howler monkeys in human-modified rural areas of Pampa del Indio in the Argentine humid Chaco. Landscape metrics were obtained from a supervised classification of a Landsat 8 image based on different kinds of exploited forests. Four times over a 2-year period, we surveyed howler monkey groups using loud calls heard at 113 listening posts in three habitat types: gallery woodland, riparian, and quebrachal hardwood forests. We also determined the age and sex composition of 31 groups through observation. A Bayesian spatial generalized linear mixed model using Integrated Nested Laplace Approximation with a Stochastic Partial Differential Equation to account for spatial dependence revealed a negative association between howler monkey group counts and prime habitat availability (i.e., old-growth forest). Howler group size was positively associated with patch density, while both the immature-to-adult female ratio and group size were negatively associated with the division index of prime habitat. Despite the apparent ability of howler monkeys to cope with habitat modification, prime habitat availability is crucial to the long-term conservation of A. caraya. Innovative landscape management strategies are required to ensure the long-term persistence of howler monkeys in human-modified environments under rapid change in the Gran Chaco eco-region.

Increased fluctuating asymmetry, or random differences between right and left sides, has been associated with developmental stress or developmental instability. This study examines fluctuating asymmetry (FA) of mesio-distal and bucco-lingual dimensions of deciduous maxillary molars (m¹, m²), and permanent maxillary premolars and molars (P³, P⁴, M¹, M²) of 466 rhesus macaques (Macaca mulatta) born between 1950 and 2018 from Cayo Santiago (CS), Puerto Rico. All included individuals were of known age, sex, birth year, and matriline. We assess whether a secular trend occurs in FA over a 68-year period, sex differences in FA, and whether environmental or management factors in the colony history resulted in decreased FA. Regression of FA on birth year tested for a secular trend in FA. A mixed-model two-way analysis of variance was used to test for the influence of food supplementation, tetanus vaccination and hurricane experience during dental development on FA. Differences across matrilines in response to the management or environmental factors were tested by ANOVA. There was no significant secular trend in FA. There was limited reduction of FA with implementation of the high protein diet, and limited support for the decreased FA associated with the implementation of tetanus vaccination. There is also limited difference in dental FA associated with exposure to a hurricane during dental development. Matrilineal differences in FA were observed for several teeth. The free-ranging environment of Cayo Santiago is a complex environment, with many factors influencing the development of young rhesus macaques. While the introduction of a high protein diet or the implementation of a tetanus vaccination program may have improved individual health overall, there are likely other factors that may cause developmental stress and result in dental FA.

We analyzed blood biochemical parameters in two groups, Callithrix jacchus (C. jacchus) and Saimiri sciureus (S. sciureus), in sympatry in the Atlantic Forest, Northeastern Brazil. The procedures included precapture and capture for health assessment and blood collection between January and September 2019. The parameters analyzed were triglycerides, total cholesterol (TC), VLDL, LDL, HDL, total protein (TP), albumin, globulins, urea, and creatinine (this only in S. sciureus). Females in C. jacchus group presented high means of TC (195.4 ± 34.8 mg/dL), LDL (76.6 ± 57.6 mg/dL), and HDL (142.7 ± 86.4 mg/dL) in relation to other cited literature values, and there were significant differences in TC, protein profile, and urea when comparing ages. Females in the S. sciureus group had higher means of TC (463.9 ± 101.8 mg/dL), HDL (137.3 ± 65.5 mg/dL), and albumin (4.95 ± 0.8 g/dL) and juveniles had higher means of HDL (116.3 ± 67.8 mg/dL), TP (15.62 ± 3.3 g/dL), albumin (4.62 ± 0.7 g/dL), and globulin (10.99 ± 3.6 g/dL). The animals were clinically healthy and the data presented can help in understanding the clinical health conditions of these species, as well as provide subsidies in the development of conservation strategies.