Factors Affecting Sleep/vigilance Behaviour in Incubating Mallards

Authors

  • Veronika Javůrková,

    1.  Department of Zoology, Biodiversity Research Group, Charles University in Prague, Praha 2, Czech Republic
    Search for more papers by this author
  • David Hořák,

    1.  Department of Ecology, Charles University in Prague, Praha 2, Czech Republic
    Search for more papers by this author
  • Jakub Kreisinger,

    1.  Department of Zoology, Biodiversity Research Group, Charles University in Prague, Praha 2, Czech Republic
    Search for more papers by this author
  • Petr Klvaňa,

    1.  Department of Zoology, Biodiversity Research Group, Charles University in Prague, Praha 2, Czech Republic
    2.  Bird Ringing Centre, National Museum, Praha 10, Czech Republic
    Search for more papers by this author
  • Tomáš Albrecht

    1.  Department of Zoology, Biodiversity Research Group, Charles University in Prague, Praha 2, Czech Republic
    2.  Institute of Vertebrate Biology v. v. i., Academy of Sciences of the Czech Republic, Brno, Czech Republic
    Search for more papers by this author

Veronika Javůrková, Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44, Praha 2, Czech Republic.
E-mail: javurko1@natur.cuni.cz

Abstract

Vigilance is a behavioural tactic that allows individuals to control their surroundings and to assess predation risk. In contrast, sleep is unique behavioural state with widely hypothesized restorative and energy-saving functions, but reducing attentiveness and increasing susceptibility to predation. Sleeping birds resolve this conflict by interrupting sleep with short periods of eye opening (termed ‘scans’) during vigilant sleep. Miscellaneous environmental factors and sleeping postures may affect the perception of risk and corresponding vigilance level. Here, we investigated the influence of nest vegetation concealment, time of day and sleeping postures on the sleep/vigilance trade-off in incubating Mallards (Anas platyrhynchos). 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; however, mean nest vegetation concealment did not affect female vigilance. 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.

Ancillary