DOI: 10.5061/dryad.7k525
title: Data from: Effects of experimental night lighting on the daily timing of winter foraging in common European songbirds

description: The ecological effects of light pollution are becoming better understood,
 especially in birds. Recent studies have shown that several bird species
 can use street lighting to extend activity into the night during the
 breeding season. However, most of these studies are correlational and
 little is known about the effects of artificial night lighting on the
 timing of activities outside the breeding season. During winter, low
 temperatures and short days may limit foraging opportunities and can
 negatively affect survival of resident birds. However, night lighting may
 allow them to expand the time niche available for foraging. Here, we
 report on a study where we repeatedly manipulated the amount of night
 lighting during early winter at automated feeding stations in a natural
 forest. We used video-recordings at the feeders to determine the time of
 the first (at dawn) and last (at dusk) foraging visits for six songbird
 species. We predicted that all species, and in particular the naturally
 early-foraging species, would advance their daily onset of foraging during
 the mornings with night lighting, but would show minimal or no delays in
 their daily cessation of foraging during the lighted evenings. We found
 that two early-foraging species, the blue tit and the great tit, started
 foraging earlier during the experimentally lighted mornings. However, in
 great tits, this effect was weak and restricted to nights with inclement
 weather. The light treatment did not have any effect on the start of
 foraging in the willow/marsh tit, the nuthatch, the European jay, and the
 blackbird. Artificial night lighting did not cause later foraging at dusk
 in any of the six species. Overall, our results suggest that artificial
 light during winter has only small effects on timing of foraging. We
 discuss these findings and the importance of temperature and winter
 weather in shaping the observed foraging patterns.
description: Relative times of onset
 and cessation of foragingData are shown for
 mornings (‘Dawn’ tab) and for evenings (‘Dusk’ tab) Site: experimental
 sites (N = 4). Numbers are used here and in the manuscript to designate
 the sites Treatment: whether the morning (at dawn) or evening (at dusk)
 was experimentally lighted (‘light’) or not (‘dark’) Date: day of the
 experimental morning (at dawn) and evening (at dusk), with 1 = 1 January.
 Missing days are due to experimental mishap (experimental schedule file
 available on demand). Temperature: daily air temperature at sunrise (at
 dawn) and sunset (at dusk) in degrees Celsius (obtained using
 light/temperature loggers, used to calculate the residuals of temperature
 against date in the models) Weather: whether the weather in the morning
 (at dawn) or evening (at dusk) was clement or adverse (snow and/or strong
 wind was observed) Extraction: experimenter that extracted the data (ADS =
 Arnaud Da Silva or DAD = David Diez-Méndez) Next columns: Tab ‘Dawn’:
 Daily Onset of foraging” (in min relative to sunrise) Tab ‘Dusk’ “Daily
 Cessation of foraging” (in min relative to sunset) for: Blackbird,
 Great_tit, Blue_tit, Poecile, Nuthatch, and Jay (only at dawn for the
 latter) For ‘Dawn’ Blackbird_outliers are data without the outliers after
 sunrise and Great_tit_outliers without 5 outliers &gt;40 min before
 sunrise and 2 outliers &gt;40 min after sunrise (for secondary analyses,
 see last paragraph of the methods)Foragingtimes.xls