Fight, fatigue, and flight: narrowing of attention to a threat compensates for decreased anti-predator vigilance

Abstract

Fighting carries a predation risk because animals have limited attention, constraining their ability to simultaneously engage in aggression and anti-predator vigilance. However, the influence of interspecific aggression and fatigue on the predation cost of fighting is seldom examined, although both are unignorable aspects of fighting. Here, I incorporated both factors in a series of field experiments on the cichlid If territorial males respond more strongly to conspecific territorial intruders than to heterospecific intruders, then they should delay escape more frequently during intraspecific fighting than during interspecific fighting. Consequently, although I predicted that vigilance would be decreased as fighting progresses in both cases, intraspecific aggression should decrease vigilance more than interspecific aggression. Males were also exposed to a predator approaching at different (slow or fast) speeds during these fighting bouts. Delays in predator detection and flight initiation were quantified and these predictions were tested. As predicted, males responded more strongly to intraspecific intruders, resulting in slower predator detection and fleeing times than when encountering interspecific intruders. Furthermore, flight latency decreased with increasing fight duration, suggesting that fatigue negatively influenced escape responses. However, contrary to the prediction, the vigilance decrement rate was faster in response to slow predators than in response to rapid predators, and was not influenced by intruder identity. This suggests that fighting males reserve their attention for information critical to their survival and are less vigilant toward a less-threatening (slowly approaching) predator. This cognitive allocation may be an adaptive compensation for fatigue-related low vigilance during fighting.

On how risk and group size interact to influence vigilance

“…Vigilance thus allows individuals to detect predators before it is too late to escape or to monitor rivals eyeing their resources. Vigilance will typically have a cost, as it reduces the ability to allocate time to other fitness‐enhancing activities (Blanchard, Pays, & Fritz, ; Creel et al, ; Ota, ). Therefore, animals tend to allocate more time to vigilance when the risk posed by predators or rivals increases (Lendrem, ; Cameron & Du Toit, ; McQueen et al, ).…”

Opportunistic predation reveals a hidden cost of fighting in birds

“…Therefore, predation events during escalated fighting might occur frequently in this model system. This account is a rare (anecdotal) evidence that escalated fighting incurs a direct predation cost due to distraction, exposure (predator attraction), injury, fatigue, or a combination of these contest-driven mechanisms (Watari and Komine 2016;Jakobsson et al 1995;Ota 2018). This casual observation recovers the idea that predation risk should be an important cost associated with escalated fighting (Jakobsson et al 1995), which has important implications relative to the evolution of signaling.…”

“…Escalated fighting might incur costs in terms of injuries (Drews 1996) and expenditure of energy and time (Davies 1985), potentially leading to fatigue (Ota 2018) or death (Riechert 1988;Hof and Hazlett 2012). Yet another possible cost of contests is an increased predation risk for individuals engaged in escalated fighting (Jakobsson et al 1995;Díaz-Uriarte 1999; "the predation-risk hypothesis").…”

“…Yet another possible cost of contests is an increased predation risk for individuals engaged in escalated fighting (Jakobsson et al 1995;Díaz-Uriarte 1999; "the predation-risk hypothesis"). This hypothesis is based on evidence that wild animals become distracted and more exposed during contests (Dunn et al 2003;Hess et al 2016;Ota 2018), and thus presumably subject to a higher risk of predation. The predation-risk hypothesis also relies on the idea that an injured or fatigued animal becomes more vulnerable to predation (Krause et al 2017;Ota 2018).…”

“…This hypothesis is based on evidence that wild animals become distracted and more exposed during contests (Dunn et al 2003;Hess et al 2016;Ota 2018), and thus presumably subject to a higher risk of predation. The predation-risk hypothesis also relies on the idea that an injured or fatigued animal becomes more vulnerable to predation (Krause et al 2017;Ota 2018). Accordingly, predation risk has been linked to fewer aggressive interactions (Kelly and Godin 2001), reduced territory size (Kim et al 2011), and altered fighting outcomes (Koga and Ikeda 2010).…”