Table 1.
Reactive anti-predator behaviors performed by large terrestrial mammals when encountering predators, their hypothesized adaptive functions (adapted from [20]), and predictions of the most effective response to each hunting style.
Fig 1.
[A] Map of study sites with [B-E] characteristics of spotted hyenas, wild dogs, cheetahs, and lions which may influence prey’s choice of anti-predator behavioral response. [B] Hunting style, dichotomized as coursing or ambush; [C] Predator density, in predators/km2; [D] Prey preference, the degree to which predators select for each individual prey species, represented by a Jacobs’ preference index which ranges from -1 (strong avoidance) to +1 (strong preference); [E] Capture success, the proportion of initiated hunts that end in a kill for each prey species. See text for references.
Fig 2.
Anti-predator behavioral strategies adopted by focal prey species relative to predator traits.
Impala relied on the same suite of behaviors, modulating the intensity of their response relative to multiple predator traits. Wildebeest altered the type and intensity of response, but only responded to predator capture success. Zebra adjusted both the type and intensity of behaviors performed in response to multiple characterizations of threat. Colored blocks correspond to predator traits that were strongly supported to affect response performance with +/- indicating the direction of the response. Relative predator density was never a significant driver of anti-predator tactics and is therefore unlisted.
Fig 3.
Strongly supported effects of social and environmental variables on anti-predator decision-making.
[A] Wildebeest were more likely to form defensive clumps when more conspecifics were present. In all three focal species [B] alarm-calling frequency increased with group size, [C] alarm-calling frequency decreased when heterospecifics were present, and [D] flight occurred sooner in experimental trials that took place in closed habitats. Baseline performance of these behaviors was higher in wildebeest than in zebra and impala for alarm-call frequency [B, C] and lower for latency to flee [D]. Probability of behavioral response and log-odds ratio for choice [A] and intensity [B-D] of responses, respectively, are depicted with associated 95% CIs.
Fig 4.
Strongly-supported effects on type of anti-predator behaviors chosen.
[A] Zebra and wildebeest were more and less likely to flee, respectively, from increasingly successful predators. [B] Zebra were more likely to flee from coursing predators than ambush predators and fled more often from coursing predators than either impala or wildebeest did. [C] Wildebeest were increasingly likely to alarm-call in encounters with ambush predators than either impala or zebra. Depicted are log-odds ratios with associated 95% CIs. Ratios above and below 0 (dashed line) indicate that the outcome is more or less likely. For [A] and [C], solid significance lines indicate differences in response to stimuli within a species while dashed significance lines represent inter-species differences in response to the same stimulus.
Fig 5.
Strongly supported predator trait effects on intensity of anti-predator response.
[A] All species were increasingly vigilant when encountering successful hunters. [B] Zebra fled sooner from encounters with successful predators. [C] Impala alarm-called more frequently towards predators that preferentially hunted impala. [D] Impala directed longer periods vigilance towards ambush predators than coursing predators, while zebra were more vigilant facing coursing predators than either of the other two species. [E] Zebra fled sooner from coursing predators than ambush predators and fled encounters with coursing predators earlier than wildebeest or impala. Impala fled sooner from ambush predators than other species did. [F] When encountering ambush predators, wildebeest alarm-called sooner than zebra. Depicted are log-odds (duration, vigilance) or hazard (latencies) ratios with associated 95% CIs. Ratios above and below 0 (dashed line) indicate that the outcome is more or less likely to occur, respectively. Solid significance lines represent differences in response to stimuli within a single species while dashed significance lines represent inter-species differences in response to the same stimulus.