Coordination and Synchronisation of Anti-Predation Vigilance in Two Crane Species

Abstract

Much of the previous research on anti-predation vigilance in groups has assumed independent scanning for threats among group members. Alternative patterns that are based on monitoring the vigilance levels of companions can also be adaptive. Coordination of vigilance, in which foragers avoid scanning at the same time as others, should decrease the odds that no group member is alert. Synchronisation of vigilance implies that individuals are more likely to be vigilant when companions are already vigilant. While synchronisation will increase the odds that no one is vigilant, it may allow a better assessment of potential threats. We investigated temporal sequences of vigilance in family flocks consisting of two parents and at most two juveniles in two species of cranes in coastal China. We established whether the observed probability that at least one parent is alert was greater (coordination) or lower (synchronisation) than that predicted under the null hypothesis of independent vigilance. We documented coordination of vigilance in common cranes (Grus grus) foraging in an area with high potential for disturbance by people. We documented synchronisation of vigilance in red-crowned cranes (Grus japonensis) in the less but not in the more disturbed area. Coordination in small flocks leads to high collective vigilance but low foraging rates that may not be suitable in areas with low disturbance. We also argue that synchronisation should break down in areas with high disturbance because periods with low vigilance are riskier. Results highlight the view that temporal patterns of vigilance can take many forms depending on ecological factors.

New perspectives in gaze sensitivity research

“…Other studies have used snapshots of group behavior to determine whether individuals were exhibiting vigilant behavior at the same time more or less than would be predicted statistically. These studies provide evidence that animals do monitor their neighbors, and tend of synchronize, rather than asynchronize their vigilance (Beauchamp, 2009;Ge, Beauchamp, & Li, 2011;Pays, Renaud, et al 2007). We suggest that measuring gaze following could also provide a direct measure of visual monitoring.…”

Difficulties in Monitoring Conspecifics Mediate the Effects of Visual Obstruction on the Level and Synchronization of Vigilance

“…It has also been suggested that by synchronizing their vigilance bouts, individuals could reduce the risk of being left behind during an attack, which could be dangerous if predators preferentially target laggards (Sirot and Touzalin, 2009). Vigilance synchronization has been documented in several species of birds and mammals, suggesting that monitoring neighbors is common in prey species (Fernández-Juricic et al, 2004;Pays et al, 2007aPays et al, ,b, 2009Pays et al, , 2012Beauchamp, 2009;Ge et al, 2011;Michelena and Deneubourg, 2011;Öst and Tierala, 2011;Butler et al, 2016;Podgórski et al, 2016).…”

Collective Vigilance in the Wintering Hooded Crane: The Role of Flock Size and Anthropogenic Disturbances in a Human‐Dominated Landscape

“…; Ge et al. ; Brandl & Bellwood ). The rarity of cases for vigilance coordination could be explained by the cost of monitoring neighbors and organizing vigilance accordingly that may offset the associated benefits (Ward ).…”