Extent of threat detection depends on predator type and behavioral context in wild samango monkey groups

Abstract

Detecting predators requires information, and many behavioral and environmental features are predicted to enhance or limit an animal's ability to learn about potential danger. Animals living in groups are thought to be at an advantage for learning about predator presence, but individual safety also depends on cues spreading from detectors to non-detectors as unsuspecting individuals may still be vulnerable. In this study we simulated predator presence among two groups of wild samango monkeys (Cercopithecus albogularis schwarzi) to mimic natural encounters where only some individuals within a primate social group have access to personal information about potential threats. We did this using visual models of natural predators placed in positions for the monkeys to encounter within the landscape for a limited amount of time. We measured the number of individuals that were observed to detect and respond to these models with antipredator reactions, relative to subgroup size. While initial detectors that were able to spot the model themselves always reacted with overt behaviors such as alarm calling or staring at the model, responses did not typically spread to all group members. The number of initial detectors was also only weakly associated with the number of individuals that responded at the end of a trial. Initial responses to leopards were much stronger and more likely to spread than those given in response to pythons or eagles and the importance of behaviors assumed to have an antipredator function depended on the type of predator the samangos encountered. Significance StatementEarly detection is critical for prey to survive an encounter with an ambush predator. Social prey have the advantage of being able to rely on cues from conspecifics, though individuals that do not detect a potential threat can still be susceptible to attack. Here we exposed wild samango monkeys to predator models to simulate predator presence to only part of a social group. Habitat visibility was a key predictor affecting collective detection, but the importance of other hypothesized factors-scanning and group spatial cohesion depended on the predator species. Overall, our results indicate that the social effectiveness of purported risk-sensitive strategies varies based on the type of threat encountered.

Hand preference predicts behavioral responses to threats in Barbary macaques

“…However, the intensity of effects on the individuals varied with the type of predator model; overall, the tiger model elicited a stronger response than the snake model. This observation was in line with previous studies that showed varying antipredator responses to different predators (LaBarge et al, 2021; Lemasson et al, 2009). Barbary macaques were found to display antipredator behavior even to play‐backs of dog alarm calls, whereas snake alarm calls failed to elicit a response (Fischer & Hammerschmidt, 2001).…”

“…However, the intensity of effects on the individuals varied with the type of predator model; overall, the tiger model elicited a stronger response than the snake model. This observation was in line with previous studies that showed varying antipredator responses to different predators (LaBarge et al, 2021;Lemasson et al, 2009).…”

Cortisol metabolites vary with environmental conditions, predation risk, and human shields in a wild primate, Cercopithecus albogularis

“…Previous studies with this group indicate that animals perceive less risk from terrestrial predators when near humans (Nowak et al, 2014), and studies on terrestrial predators like leopards (Van Cleave et al, 2018) indicate that these animals tend to avoid people. Unfortunately, we could not identify differences in responses between predator types, although some evidence indicates that this study population tends to respond more intensely to leopards and eagles than snakes (LaBarge et al, 2021). Additionally, with such a large study group, individuals are less likely to be near a single observer for long periods of the day.…”

When aggressiveness could be too risky: linking personality traits and predator response in superb fairy-wrens

“…This suggests that conspecific aggressiveness is associated with predator-response behaviours in this species, albeit in a non-linear fashion. Responding to a predator quickly and closely could reduce the risk of nest predation, by alerting other group members to the threat and facilitating the performance of distraction displays to draw the predators’ attention ( Kleindorfer, Fessl & Hoi, 2005 ; LaBarge et al, 2021 ; Rowley, 1962 ; Zuberbühler, 2001 ). However, such a strong response would presumably also place the responders at greater risk of being predated themselves, making the net fitness benefits unclear.…”