Abduction and potential case of predation of an infant howler monkey (Alouatta guariba clamitans) by a tufted capuchin monkey (Sapajus nigritus)

The likelihood of interspecific interactions between wild primates is particularly high for species with overlapping territories. The sharing of the same or similar ecological niches can result in competition for space or resources, which can lead to agonistic encounters such as predator-prey interactions. Here, we report the observation of an abduction and potential case of predation of an infant howler monkey (Alouatta guariba clamitans) by an adult male capuchin monkey (Sapajus nigritus) in Minas Gerais, Brazil. Evidence of capuchin monkeys' predation of other smaller sympatric primate species has already been reported, as well as description of agonistic interactions between capuchin and howler monkeys, but none as drastic as the case described here. Although we were not able to collect evidence after the abduction, we discuss the events leading up to it and present arguments in favour of the case of interspecific predation or infanticid

Impact of predator model presentation paradigms on titi monkey alarm sequences

Predator presentation experiments are widely used to investigate animal alarm vocalizations. They usually involve presentations of predator models or playbacks of predator calls, but it remains unclear whether the two paradigms provide similar results, a major limitation when investigating animal syntactic and semantic capacities. Here, we investigate whether visual and acoustic predator cues elicit different vocal reactions in black-fronted titi monkeys (Callicebus nigrifrons). We exposed six groups of wild titi monkeys to visual models or playbacks of vocalizations of raptor or felid. We characterized each group’s vocal reactions using sequence parameters known to reliably encode predatory events in this species. We found that titi monkeys’ vocal reactions varied with the predator species but also with the experimental paradigm: while vocal reactions to raptor vocalizations and models were similar, felid vocalizations elicited heterogeneous, different reactions from that given to felid models. We argue that subjects are not familiar with felid vocalizations, because of a lack of learning opportunities due to the silent behaviour of felids. We discuss the implication of these findings for the semantic capacities of titi monkeys. We finally recommend that playbacks of predator vocalizations should not be used in isolation but in combination with visual model presentations, to allow fine-grained analyses of the communication system of prey species. Significance statement - It is common to present prey species with predator models or predator calls to study their vocal reactions. The two paradigms are often used independently, but it remains unclear whether they provide similar results. Here, we studied the vocal reactions of titi monkeys to calls and models of raptors and felids. We show that titi monkeys seem to recognize the vocalizations of raptors but not those of felids. The study of the vocal reactions emitted when titi monkeys cannot clearly identify the threat allows us to draw accurate hypotheses about the meaning of titi monkeys’ alarm utterances. We argue that playbacks of predator calls should be used in conjunction with model presentations, which can allow us to better investigate the information and the structure of the alarm systems

Impact of predator model presentation paradigms on titi monkey alarm sequences

Open access funding provided by University of Zurich. This work received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement no. 283871 (PI: KZ), the Swiss National Science Foundation (NCCR Evolving Language, Swiss National Science Foundation Agreement #51NF40_180888) and the University of Neuchâtel.Predator presentation experiments are widely used to investigate animal alarm vocalizations. They usually involve presentations of predator models or playbacks of predator calls, but it remains unclear whether the two paradigms provide similar results, a major limitation when investigating animal syntactic and semantic capacities. Here, we investigate whether visual and acoustic predator cues elicit different vocal reactions in black-fronted titi monkeys (Callicebus nigrifrons). We exposed six groups of wild titi monkeys to visual models or playbacks of vocalizations of raptor or felid. We characterized each group’s vocal reactions using sequence parameters known to reliably encode predatory events in this species. We found that titi monkeys’ vocal reactions varied with the predator species but also with the experimental paradigm: while vocal reactions to raptor vocalizations and models were similar, felid vocalizations elicited heterogeneous, different reactions from that given to felid models. We argue that subjects are not familiar with felid vocalizations, because of a lack of learning opportunities due to the silent behaviour of felids. We discuss the implication of these findings for the semantic capacities of titi monkeys. We finally recommend that playbacks of predator vocalizations should not be used in isolation but in combination with visual model presentations, to allow fine-grained analyses of the communication system of prey species. Significance statement: It is common to present prey species with predator models or predator calls to study their vocal reactions. The two paradigms are often used independently, but it remains unclear whether they provide similar results. Here, we studied the vocal reactions of titi monkeys to calls and models of raptors and felids. We show that titi monkeys seem to recognize the vocalizations of raptors but not those of felids. The study of the vocal reactions emitted when titi monkeys cannot clearly identify the threat allows us to draw accurate hypotheses about the meaning of titi monkeys’ alarm utterances. We argue that playbacks of predator calls should be used in conjunction with model presentations, which can allow us to better investigate the information and the structure of the alarm systems.Publisher PDFPeer reviewe

Contextual encoding in titi monkey alarm call sequences

Our research was funded by the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement n° 283871. We acknowledge further funding from the University of Neuchâtel and logistic support from the Santuário do Caraça.Many primates produce one type of alarm call to a broad range of events, usually terrestrial predators and non-predatory situations, which raises questions about whether primate alarm calls should be considered “functionally referential”. A recent example is black-fronted titi monkeys, Callicebus nigrifrons, which emit sequences of B-calls to terrestrial predators or when moving towards or near the ground. In this study, we reassess the context-specificity of these utterances, focussing both on their acoustic and sequential structure. We found that B-calls could be differentiated into context-specific acoustic variants (terrestrial predators vs. ground-related movements) and that call sequences to predators had a more regular sequential structure than ground-related sequences. Overall, these findings suggest that the acoustic and temporal structure of titi monkey call sequences discriminate between predator and non-predatory events, fulfilling the production criterion of functional reference.PostprintPeer reviewe

Acoustic sequences in non-human animals: a tutorial review and prospectus.

Animal acoustic communication often takes the form of complex sequences, made up of multiple distinct acoustic units. Apart from the well-known example of birdsong, other animals such as insects, amphibians, and mammals (including bats, rodents, primates, and cetaceans) also generate complex acoustic sequences. Occasionally, such as with birdsong, the adaptive role of these sequences seems clear (e.g. mate attraction and territorial defence). More often however, researchers have only begun to characterise - let alone understand - the significance and meaning of acoustic sequences. Hypotheses abound, but there is little agreement as to how sequences should be defined and analysed. Our review aims to outline suitable methods for testing these hypotheses, and to describe the major limitations to our current and near-future knowledge on questions of acoustic sequences. This review and prospectus is the result of a collaborative effort between 43 scientists from the fields of animal behaviour, ecology and evolution, signal processing, machine learning, quantitative linguistics, and information theory, who gathered for a 2013 workshop entitled, 'Analysing vocal sequences in animals'. Our goal is to present not just a review of the state of the art, but to propose a methodological framework that summarises what we suggest are the best practices for research in this field, across taxa and across disciplines. We also provide a tutorial-style introduction to some of the most promising algorithmic approaches for analysing sequences. We divide our review into three sections: identifying the distinct units of an acoustic sequence, describing the different ways that information can be contained within a sequence, and analysing the structure of that sequence. Each of these sections is further subdivided to address the key questions and approaches in that area. We propose a uniform, systematic, and comprehensive approach to studying sequences, with the goal of clarifying research terms used in different fields, and facilitating collaboration and comparative studies. Allowing greater interdisciplinary collaboration will facilitate the investigation of many important questions in the evolution of communication and sociality.This review was developed at an investigative workshop, “Analyzing Animal Vocal Communication Sequences” that took place on October 21–23 2013 in Knoxville, Tennessee, sponsored by the National Institute for Mathematical and Biological Synthesis (NIMBioS). NIMBioS is an Institute sponsored by the National Science Foundation, the U.S. Department of Homeland Security, and the U.S. Department of Agriculture through NSF Awards #EF-0832858 and #DBI-1300426, with additional support from The University of Tennessee, Knoxville. In addition to the authors, Vincent Janik participated in the workshop. D.T.B.’s research is currently supported by NSF DEB-1119660. M.A.B.’s research is currently supported by NSF IOS-0842759 and NIH R01DC009582. M.A.R.’s research is supported by ONR N0001411IP20086 and NOPP (ONR/BOEM) N00014-11-1-0697. S.L.DeR.’s research is supported by the U.S. Office of Naval Research. R.F.-i-C.’s research was supported by the grant BASMATI (TIN2011-27479-C04-03) from the Spanish Ministry of Science and Innovation. E.C.G.’s research is currently supported by a National Research Council postdoctoral fellowship. E.E.V.’s research is supported by CONACYT, Mexico, award number I010/214/2012.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1111/brv.1216

Terrestrial behavior in titi monkeys (Callicebus, Cheracebus, and Plecturocebus) : potential correlates, patterns, and differences between genera

For arboreal primates, ground use may increase dispersal opportunities, tolerance to habitat change, access to ground-based resources, and resilience to human disturbances, and so has conservation implications. We collated published and unpublished data from 86 studies across 65 localities to assess titi monkey (Callicebinae) terrestriality. We examined whether the frequency of terrestrial activity correlated with study duration (a proxy for sampling effort), rainfall level (a proxy for food availability seasonality), and forest height (a proxy for vertical niche dimension). Terrestrial activity was recorded frequently for Callicebus and Plecturocebus spp., but rarely for Cheracebus spp. Terrestrial resting, anti-predator behavior, geophagy, and playing frequencies in Callicebus and Plecturocebus spp., but feeding and moving differed. Callicebus spp. often ate or searched for new leaves terrestrially. Plecturocebus spp. descended primarily to ingest terrestrial invertebrates and soil. Study duration correlated positively and rainfall level negatively with terrestrial activity. Though differences in sampling effort and methods limited comparisons and interpretation, overall, titi monkeys commonly engaged in a variety of terrestrial activities. Terrestrial behavior in Callicebus and Plecturocebus capacities may bolster resistance to habitat fragmentation. However, it is uncertain if the low frequency of terrestriality recorded for Cheracebus spp. is a genus-specific trait associated with a more basal phylogenetic position, or because studies of this genus occurred in pristine habitats. Observations of terrestrial behavior increased with increasing sampling effort and decreasing food availability. Overall, we found a high frequency of terrestrial behavior in titi monkeys, unlike that observed in other pitheciids