Risk awareness of black-and-gold howler monkeys living in an urban environment in south-west Paraguay

As urbanisation increases, wild primates are exposed to urban environments which come with a distinct and often novel set of risks. Urban habitats can form a matrix of forest fragments and anthropogenic structures, including buildings, electric cables and roads, which can limit movement and force species to live in hazardous areas. We studied five groups of urban black and gold howler monkey (Alouatta caraya) in Pilar, Paraguay, to investigate whether the monkeys are aware of anthropogenic risks based on their patterns of self-scratching behaviour, an indicator of stress, and how they used the space available to them. Using a Risk Index created for the study, we ranked the level of risk attributed to different zones of their home range, awarding each zone with a hazard score. Using Quantum GIS and kernel density estimation, we determined the relationship between habitat use and hazard score. Using a Spearman’s rank correlation, we found nonsignificant relationships between the hazard score and self-scratching behaviour for four groups, suggesting a lack of awareness. However, there was a significant negative relationship between the hazard score and home range use for four groups, indicating that they spent more time in areas with lower levels of anthropogenic risk.