Skyglow relieves a crepuscular bird from visual constraints on being active
Ruben Evens1, Michiel Lathouwers2, Jean-Nicolas Pradervand3
1Department of Biology, Behavioural Ecology and Ecophysiology group, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium.
The Science of the Total Environment
|July 28, 2023
Summary
Artificial light at night, or skyglow, increases bird flight activity, even on cloudy nights. This adaptation to artificial light cycles may impact nocturnal species
Area of Science:
- Ecology
- Animal Behavior
- Environmental Science
Background:
- Artificial light at night (ALAN) disrupts natural light cycles, crucial Zeitgebers for animal activity.
- Skyglow, indirect illumination from ALAN, is increasing globally, but its impact on wildlife behavior is understudied.
- Previous research on ALAN's effects has been limited to controlled laboratory settings.
Purpose of the Study:
- To investigate the impact of skyglow on the flight activity of free-living crepuscular birds.
- To compare nocturnal light conditions and bird activity across sites with varying skyglow exposure.
- To understand how artificial night-sky brightness influences daily and seasonal activity patterns.
Main Methods:
- Utilized animal-borne activity loggers to monitor flight activity in European Nightjars (Caprimulgus europaeus).
- Compared activity data from sites with high skyglow (Belgium) versus near-pristine skies (Africa, Mongolia).
- Analyzed flight activity in relation to natural light cycles (moon phase, cloud cover) and artificial sky brightness.
Main Results:
- Nightjar flight activity during moonless nights was four times higher in high skyglow areas compared to pristine sites.
- The response to cloud cover was reversed: cloudy nights reduced activity in pristine areas but increased it under skyglow.
- Artificial sky brightness allows nightjars to extend their active periods, relieving natural visual constraints.
Conclusions:
- Anthropogenic skyglow significantly alters nocturnal behavior by extending available activity time for nightjars.
- This adaptation to artificial light cycles likely affects numerous crepuscular and nocturnal species.
- Further research is needed to explore implications for population dynamics and interspecific interactions.
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