Do Wild Great Tits Avoid Exposure to Light at Night?

PLoS One. 2016 Jun 29;11(6):e0157357. doi: 10.1371/journal.pone.0157357. eCollection 2016.

Abstract

Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their nighttime light exposure by seeking dark spots within illuminated areas. This uncertainty makes it difficult to attribute effects to a direct effect of light at night, or to indirect effects, e.g., via an effect of light at night on food availability. In this study, we aim to quantify the nocturnal light exposure of wild birds in a previously dark forest-edge habitat, experimentally illuminated with three different colors of street lighting, in comparison to a dark control. During two consecutive breeding seasons, we deployed male great tits (Parus major) with a light logger measuring light intensity every five minutes over a 24h period. We found that three males from pairs breeding in brightly illuminated nest boxes close to green and red lamp posts, were not exposed to more artificial light at night than males from pairs breeding further away. This suggests, based on our limited sample size, that these males could have been avoiding light at night by choosing a roosting place with a reduced light intensity. Therefore, effects of light at night previously reported for this species in our experimental set-up might be indirect. In contrast to urban areas where light is omnipresent, bird species in non-urban areas may evade exposure to nocturnal artificial light, thereby avoiding direct consequences of light at night.

MeSH terms

  • Animals
  • Animals, Wild
  • Circadian Rhythm
  • Ecosystem
  • Environmental Pollution
  • Female
  • Light*
  • Male
  • Passeriformes / physiology*
  • Photic Stimulation
  • Reproduction
  • Sexual Behavior, Animal*

Grants and funding

This research is supported by the Dutch Technology Foundation STW, which is part of the Netherlands Organization for Scientific Research (NWO) and which is partly funded by the Ministry of Economic Affairs. The project is supported by Philips and the Nederlandse Aardolie Maatschappij (NAM). JQO was supported by an NSF postdoctoral research fellowship in biology (DBI-1306025). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.