Multiple antipredator behaviors in wild red-tailed monkey (Cercopithecus ascanius) groups reveal spatially distinct landscapes of fear

Predation risk influences how prey animals behave. In wild red-tailed monkeys, we found little overlap in the areas where the monkeys alarm-called, were vigilant, and grouped together closely. Anti-predator behaviors were also influenced by vegetation type and the extent to which the various anti-predator behaviors were shown by group members. Different antipredator behaviors seem to be applied under different contexts. Measuring only one antipredator behavior in a study may offer therefore an imperfect measure of the perceived risk of predation. Foraging opportunity and predation risk act as opposing influences on an animal's habitat use. Landscapes of fear (LOF), whereby one predicts the spatial distribution of predators or perceived predator presence using prey responses, are an important tool for modeling this conflict. LOF models examining perceived predation risk are often generated using a single behavioral metric, even though individuals can respond to predation pressure with multiple potential behaviors. Here, we expanded traditional LOF approaches by measuring three antipredator behaviors in wild red-tailed monkeys (Cercopithecus ascanius): aggregation, alarm calling, and vigilance. We predicted that each behavior would reveal spatially explicit regions of high risk, as each behavior may attend to different aspects of perceived predation risk. The use of different behaviors may depend upon factors such as vegetation type, age/sex class of an individual, and which other antipredator behaviors are being exhibited by group members. We collected data on two troops of monkeys in the Issa Valley, Tanzania for over 19 months and conducted 3189 group follows. We found that vegetation type varied in its effect on antipredator behavior. Monkeys conducted more antipredator behavior in more open vegetation types compared to more closed, riparian forests. The LOF models generated for each behavior mapped distinct and predominantly non-overlapping spatial regions of perceived predation risk, which was replicated across the two groups. This suggested that monkeys responded differently across their home range to specific perceived risks. Such spatially explicit behavior may indicate vegetation-specific predation risk or unique trade-offs in antipredator behavior throughout a heterogenous habitat.

Automated summary

Prey animals' behaviors are influenced by predation risk, and this influence has been observed in wild red-tailed monkeys. The type of vegetation and the antipredator behaviors exhibited by group members also affect the expressions of these behaviors. Different antipredator behaviors are used in different contexts. Measuring only one antipredator behavior may not provide a complete and accurate measure of the perceived predation risk.