Geophagy in large-headed capuchin monkeys (Sapajus apella macrocephalus) in the Reserva Nacional Tambopata, Peru.

Many primate species have been observed descending to the forest floor to intentionally consume soil (geophagy) at licks. The practice of geophagy is assumed to provide health benefits, such as mineral supplementation and/or gastrointestinal tract protection. We collected data on geophagy events through the use of camera traps at Tambopata National Reserve in southeastern Peru. Two geophagy sites were monitored for 42 months, during which time we observed repeated geophagy events by a group of large-headed capuchin monkeys (Sapajus apella macrocephalus). To the best of our knowledge, this is the first report of its kind for the species. Geophagy was rare, with only 13 events recorded over the study period. All but one event took place during the dry season, and 85% of events took place in the late afternoon between 1600 and 1800 hours. The monkeys were observed consuming soil both in situ and ex situ, and displayed heightened vigilance behavior during geophagy events. Although the small sample size makes it difficult to draw clear conclusions as to the drivers of this behavior, the seasonal timing of the events and the high percentage of clay in the consumed soils suggest that these events are linked to the detoxification of secondary plant compounds in the monkeys' diet.

Report of an attack on a howler monkey Alouatta sara by a group of collared peccaries Dicotyles tajacu at a mammal clay lick in Madre de Dios, Peru.

Howler monkeys Alouatta are almost exclusively arboreal. They will, however, occasionally descend to the forest floor to conduct geophagy at clay licks if these are present within their home range. They do this to incorporate certain minerals into their diet and/or for detoxification purposes. Clay licks are risky areas however, especially for arboreal mammals, as visiting them requires the monkeys to leave the safety of the trees. This has been confirmed by observed predation attempts on howler monkeys by large felines at clay licks. We report an additional risk for howler monkeys descending to the forest floor that has not previously been considered, namely potential attacks by collared peccaries Dicotyles tajacu. Camera traps were placed at three different clay licks in the Taricaya Ecological Reserve, located in the southeastern Peruvian Amazon, to monitor the fauna within the reserve. On 4 June 2017, the camera traps registered a lethal attack on a howler monkey by a group of collared peccaries at one of the clay licks.

Factors influencing establishment success in reintroduced black-faced spider monkeys Ateles chamek.

Establishing reintroduced primates in a suitable predetermined area has proven to be a challenge. Establishment is the first major step that has to be taken in the long process of reintroduction. When this first goal is not achieved, the chances of success decline drastically. Understanding the main determinants of establishment is therefore crucial for reintroduction success. This study examined the influence of three independent factors on the establishment success of reintroduced spider monkeys. We analysed data from the releases of eight groups of black-faced spider monkeys (Ateles chamek), which are part of the official reintroduction program of spider monkeys in the South Eastern Peruvian Amazon. Establishment success was measured by the proportion of individuals within groups that were found in the target area 6 months after release. The hours research assistants and volunteers spent with the group within the first 3 months after release-in the context of post-release monitoring-was shown to have a positive effect on the establishment success of the released group in the target area. The presence of an already established group in the area was also found to have a significant positive effect on establishment success. The influence of the days of post-release food provisioning had no effect. Our findings emphasize the importance of long-term monitoring programs to help increase the efficiency of primate reintroductions.