Abstract
Vigilance is a behavioural tactic that allows individuals to control their surroundings and to assess predation risk. Miscellaneous environmental factors and sleeping postures may affect the perception of risk and corresponding vigilance level.
Here we found that incubating females increased their vigilance with increasing nest vegetation cover facing the vigilant eye during both the day and the night periods. Females also reduced their total vigilance along with scan frequency during the night period, while displaying the opposite pattern during the daylight.
The rest-sleeping position was preferred more during the night compared with the daylight period, and females were more vigilant in this position at night. Our data show that the nest vegetation concealment regardless of visual abilities during different light conditions, time of day and sleeping posture play an underlying role in antipredator vigilance during sleep in this cryptic ground-nesting bird.