Eye blinking in an avian species is associated with gaze shifts

Abstract

Even when animals are actively monitoring their environment, they lose access to visual information whenever they blink. They can strategically time their blinks to minimize information loss and improve visual functioning but we have little understanding of how this process operates in birds. This study therefore examined blinking in freely-moving peacocks (Pavo cristatus) to determine the relationship between their blinks, gaze shifts, and context. Peacocks wearing a telemetric eye-tracker were exposed to a taxidermy predator (Vulpes vulpes) and their blinks and gaze shifts were recorded. Peacocks blinked during the majority of their gaze shifts, especially when gaze shifts were large, thereby timing their blinks to coincide with periods when visual information is already suppressed. They inhibited their blinks the most when they exhibited high rates of gaze shifts and were thus highly alert. Alternative hypotheses explaining the link between blinks and gaze shifts are discussed.

Figure 1. Blink and gaze shift rate before and after the predator was revealed.

Figure 2

Blink and gaze shift rate were positively related (a) before the predator was revealed and (b) after the predator was revealed.

Figure 3. Peacocks were less likely to blink during a gaze shift when they exhibited a high gaze shift rate.

Figure 4. Peacocks were less likely to blink during a gaze shift when less time lapsed since their previous blink.

Figure 5. The size of eye-in-head movements was smaller when peacocks did not blink.

Figure 6. The velocity (lsmean) of eye-in-head and head movements was slower for gaze shifts with blinks compared to gaze shifts without blinks.