Reaction to the death of the oldest female in a group of chimpanzees at the Municipal Zoological Garden, Warsaw Abstract In March 2017, the oldest female of a group of chimpanzees living in the Municipal Zoological Garden in Warsaw, died in her sleep at the age of 53, due to natural causes. The article reports reactions of the eight other individuals in the group, four males and four females, including the daughter and the granddaughter of the old female, the following day. The corpse generally elicited more interest in the females than in the adult males. The females touched the body gently and groomed it more often than the males, who tended simply to look at and sniff it. However, the most diverse reactions, ranging from gentle touching to jumping on and hitting the corpse, were seen in the youngest male. By contrast, the oldest male never approached the corpse. In general, the chimpanzees at the zoo reacted in a manner much milder than is often reported from the wild.

Sexual dimorphism in the loud calls of Azara’s owl monkeys ( Aotus azarae ): evidence of sexual selection? Abstract Primates use different types of vocalizations in a variety of contexts. Some of the most studied types have been the long distance or loud calls. These vocalizations have been associated with mate defense, mate attraction, and resource defense, and it is plausible that sexual selection has played an important role in their evolution. Focusing on identified individuals of known sex and age, we evaluated the sexual dimorphism in a type of loud calls (hoots) in a population of wild owl monkeys (Aotus azarae) in Argentina. We found evidence of sexual dimorphism in call structure, with females and males only emitting one type of call, each differing in dominant frequency and Shannon entropy. In addition, both age-related and sex-specific differences in call usage were also apparent in response to the removal of one group member. Future acoustic data will allow us to assess if there are individual characteristics and if the structure of hoot calls presents differences in relation to the social condition of owl monkeys or specific sex responses to variants of hoot calls’ traits. This will provide deeper insights into the evolution of vocal mechanisms regulating pair bonding and mate choice strategies in this and other primate species.

Elephant behavior toward the dead: A review and insights from field observations Abstract Many nonhuman animals have been documented to take an interest in their dead. A few socially complex and cognitively advanced taxa—primates, cetaceans, and proboscideans—stand out for the range and duration of behaviors that they display at conspecific carcasses. Here, we review the literature on field observations of elephants at carcasses to identify patterns in behaviors exhibited. We add to this literature by describing elephant responses to dead elephants in the Samburu National Reserve, northern Kenya. The literature review indicated that behavior of elephants at carcasses most often included approaches, touching, and investigative responses, and these occurred at varying stages of decay, from fresh carcasses to scattered and sun-bleached bones. During our own observations, we also witnessed elephants visiting and revisiting carcasses during which they engaged in extensive investigative behavior, stationary behavior, self-directed behavior, temporal gland streaming, and heightened social interactions with other elephants in the vicinity of a carcass. Elephants show broad interest in their dead regardless of the strength of former relationships with the dead individual. Such behaviors may allow them to update information regarding their social context in this highly fluid fission–fusion society. The apparent emotionality and widely reported inter-individual differences involved in elephant responses to the dead deserve further study. Our research contributes to the growing discipline of comparative thanatology to illuminate the cognition and context of nonhuman animal response to death, particularly among socially complex species.

Primate thanatology and hominoid mortuary archeology Abstract In recent years, a thanatology of primates has become a respectable research topic, and although still sparse, observations among several taxa have shown how complex responses to the dead can be. In human evolutionary archeology, re-analysis of old ‘burial’ sites is slowly revising our view on the development of specifically human responses to the dead. We propose here the means of integrating information from the two disciplines of primatology and archeology, in support of the field of primate thanatology. We propose a terminology and a shared set of research questions, from which we generate a number of observations that can be utilized in the field, in order to establish a working dialogue and foster greater collaboration across the two disciplines.

Correction to: Shape variation in the facial part of the cranium in macaques and African papionins using geometric morphometrics In the original publication of this article, the abbreviations in Fig. 2 caption should be as follows.

The  Primates  2019 Most-Cited Paper Award

Acknowledgements

The Goodness Paradox: How evolution made us more and less violent, by Richard Wrangham

Water games by mountain gorillas: implications for behavioral development and flexibility—a case report Abstract Functions of play, which may be performed solo or in a social context, include motor training and behavioral flexibility. Play is often more common in infancy and the juvenile period, although it also occurs in adults of many species. In contrast to social play, few studies have investigated solitary play. Here, we present new empirical data on solitary water play in a subadult and two adult mountain gorillas in Bwindi Impenetrable National Park, Uganda, observed on three different days between January and February 2018. Focal sampling was used to record the behavior of the individuals interacting with water. Movements included vigorous rotation of the arms, splashing the water, tilting the head, making a play face, and sweeping with the hands to create waves on the water surface. One of the episodes represents the first vigorous display of splashing water ever reported for Bwindi gorillas. Our observations highlight three significant components of mountain gorilla development and behavior: play, behavioral flexibility, and exploration.

Prevalence of gastrointestinal parasites in lion-tailed macaque Macaca silenus in central Western Ghats, India Abstract This study examines gastrointestinal parasites in the endangered lion-tailed macaque, which is sympatric with the bonnet macaque that has relocated from nearby towns or agriculture landscapes dominated by humans and livestock. One hundred and ninety-four fresh fecal samples from lion-tailed macaques were collected from a group located at Chiksuli in the central Western Ghats. Of these, 48.5% had at least one endoparasite taxon. The prevalence of endoparasites varied from 0 to 75.0%, and observed endoparasite taxa varied between 0 and 10 across different months. The prevalence of endoparasites decreased with increasing rainfall and with increasing average maximum temperature across months. Of the 17 endoparasite taxa, 11 were nematodes, two were cestodes, and four were protozoans. The prevalence of Ascaris sp. and Entamoeba coli was higher than the other taxa. The overall load, helminth load, and protozoan load did not differ between months. The overall endoparasite load was greater in immature macaques in all seasons. Helminth load was higher in adult males, especially in the summer. Comparing our findings with those from sympatric relocated bonnet macaques of Chiksuli (Kumar et al. in PLoS ONE 13(11):e0207495, 2018) and lion-tailed macaques of Anamalai Hills (Hussain et al. in PLoS ONE 8(5):e63685, 2013) revealed: (a) a much higher prevalence of endoparasites in lion-tailed macaques from fragments of Anamalai Hills than in lion-tailed and bonnet macaques of Chiksuli; (b) higher richness of endoparasites in both macaque species of Chiksuli than in Anamalai lion-tailed macaques; and (c) more similar composition of endoparasite taxa between the Chiksuli lion-tailed and bonnet macaques than with the Anamalai Hills lion-tailed macaques. We suggest a complete cessation of relocation of commensal animals to the wild habitat. If relocation is necessary, then individuals to be relocated should be thoroughly screened and treated to prevent transferring endoparasite infections to wild populations.