Cavities shield birds from effects of artificial light at night on sleep

Abstract

Light pollution is an ever increasing worldwide problem disrupting animal behavior. Artificial light at night (ALAN) has been shown to affect sleep in wild birds. Even cavity-nesting bird species may be affected when sleeping inside their cavity. Correlational studies suggest that light from outside the cavity/nest box, for example from street lights, may affect sleep. We used an experimental design to study to what extent nest boxes shield animals from effects of ALAN on sleep. We recorded individual sleep behavior of free-living great tits (Parus major) that were roosting in dark nest boxes and exposed their nest box entrance to ALAN the following night (1.6 lux white LED light; a similar light intensity as was found at nest boxes near street lights). Their behavior was compared to that of control birds sleeping in dark nest boxes on both nights. Our experimental treatment did not affect sleep behavior. Sleep behavior of birds in the control group did not differ from that of individuals in the light treated group. Our results suggest that during winter cavities shield birds from some effects of ALAN. Furthermore, given that effects of ALAN and exposure to artificial light are species-, sex-, and season-dependent, it is important that studies using wild animals quantify individual exposure to light pollution, and be cautious in the interpretation and generalization of the effects, or lack thereof, from light pollution. Rigorous studies are necessary to examine individual light exposure and its consequences in cavity- and open-nesting birds.

Effects of the Urban Environment on Oxidative Stress in Early Life: Insights from a Cross-fostering Experiment

“…2017 ). Alternatively, the immediate rearing environment of the nestlings, i.e., the enclosed nest-box, could have buffered the exposure of certain types of urban stressors, such as artificial light at night ( Raap et al. 2018 ), such that urbanization effects on AOX are not readily observed before fledging.…”

Artificial light at night as an environmental pollutant: An integrative approach across taxa, biological functions, and scientific disciplines

“…Dominoni et al (2018) assessed dose-dependent responses of the reproductive system. Raap, Pinxten, and Eens (2018) asked whether roosting in cavities may limit the effects of light pollution on sleep. Other passerine bird species included in this issue are the Indian Weaver Bird (Ploceus philippinus) and the Zebra finch ( Taeniopygia guttata ).…”

The effects of season, sex, age and weather on population‐level variation in the timing of activity in Eurasian Blue TitsCyanistes caeruleus

“…Finally, several studies showed that exposure to artificial night lighting influences activity patterns and sleep (e.g. Kempenaers et al 2010, Dominoni et al 2013, 2014, Russ et al 2015, Raap et al 2016, Sun et al 2017; but see Raap et al 2018).…”