DOI: 10.5061/dryad.47d7wm3r3
title: Under cover of darkness: Refuge from artificial light at night may mitigate risks to stranded seabirds

description: Artificial light at night is an anthropogenic pollutant that has
 wide-ranging effects on wildlife. Fledgling seabirds of order
 Procellariiformes exhibit phototaxis toward artificial lights on their
 first flights from the nest, causing them to become grounded in human
 settlements, where they are subject to increased predation risk. Limited
 evidence suggests certain light types may be less attractive than others,
 yet there is also evidence for an aversion to light under certain
 circumstances. We investigated differences in phototactic behaviour,
 activity level, and shelter-seeking behaviour of grounded Hydrobates
 leucorhous (Leach’s storm-petrel) fledglings exposed to artificial light
 in three experiments: a Y-maze choice experiment, an open field test, and
 a modified open field test with a hide box provided (“Safe Haven test”).
 When provided with combinations of different light types in the Y-maze,
 storm-petrels typically remained stationary in the darkest parts of the
 apparatus (farthest from light stimuli) and exhibited no preferred
 response toward one light type over another. This was consistent with
 results from the open field test: individuals were less active in darkness
 than when exposed to two of three light conditions (Warm White
 Light-Emitting Diode and High Pressure Sodium). More than half of
 individuals entered the hide box in light conditions, compared to none in
 darkness. Considered together, our results indicate that most (but not
 all) Leach’s storm-petrel fledglings exhibit photophobic behaviour after
 stranding, which may be part of a behavioural strategy to avoid predation.
 Further, we demonstrate the utility of providing hide boxes to protect
 stranded seabird fledglings in locations where lighting cannot be
 eliminated or where rescue efforts are limited in spatial or temporal
 coverage. However, hide boxes would have limited utility in dark
 locations. Hide boxes constitute a novel mitigation measure that merits
 future testing for its ability to reduce stranding-induced mortality,
 especially in imperiled procellariiform species.
description: # Under cover of darkness: Refuge from artificial light at night may
 mitigate risks to stranded seabirds
 [https://doi.org/10.5061/dryad.47d7wm3r3](https://doi.org/10.5061/dryad.47d7wm3r3) ## Description of the data and file structure We conducted three experiments, all with the overarching goal of studying behavioural responses of stranded fledgling Leach's Storm-Petrels (*Hydrobates leucorhous*) to artificial light in various contexts. There are thus three comma-delimited spreadsheet files available, one for each experiment, plus one additional comma-delimited file containing data used to create and apply a conversion factor to some of the data in one of our experiments (see description of "petrel-openfield-audiovisual.csv", below). The first experiment involved placing individuals in a Y-maze choice experiment with various combinations of two different artificial light types and quantifying the number of birds that responded to each type, specifically assessing any preferences for certain light types over others. In the second experiment, the same individuals exposed to the Y-maze were placed in an open field test with one of various light types and their activity levels were measured. Lastly, with different individuals and in a different year we tested the propensity of stranded fledgling Leach's Storm-Petrels to enter a provided hide box in an open field test under either light or dark conditions.  ### Files and variables #### File: petrel-safehaven.csv **Description:** Raw data from our experiment in which we tested the propensity of Leach's Storm-Petrel fledglings to enter a provided hide box in light (5000 Kelvin, Light Emitting Diode [LED]) versus dark conditions, given a 10-minute trial time. ##### Variables * id: Unique identification number of each individual * trial_order: "1" indicates the first of two trials for a given individual; "2" indicates the second trial. * treatment: Treatment to which the individual was exposed in a given trial; either light ("5000k") or "dark". In combination with variable "trial_order", one can infer to which treatments the individual was exposed first and second. * enterbox: A dichotomous variable, indicating whether the individual entered the provided Safe Haven hide box ("1"), or did not enter ("0"). * day: Day (or date) of the month in which the trial was conducted. * month: Month in which the trial was conducted. Note that all trials were conducted in October. * year: Year in which the trial was conducted. Note that all trials were conducted in 2023. #### File: petrel-ymaze.csv **Description:** Raw data from our y-maze choice experiment to measure phototactic behaviour in stranded fledgling Leach's Storm-Petrels, including information on latency to make a choice (i.e., to "respond") to one of the two provided light types in a given treatment group (i.e., "choice combination"). ##### Variables * id: Unique identification number of each individual * treatment: I.e., "choice combination"; the light types presented to the individual in each of two choice boxes, separated by an en dash. "hps" refers to High Pressure Sodium; "dark" refers to darkness (i.e., no light); "blue" refers to blue LED light; "orange" refers to orange LED light; 2700K refers to warm white LED light; 5000K refers to cool white LED light  (see Brown et al., 2025; Ornithological Applications, for further details on materials used and spectral characteristics of each light type). * box 1: The light type presented in choice box #1 to a given individual. * box 2: The light type presented in choice box #2 to a given individual. * push: A dichotomous variable, indicating whether the individual was prodded ("y") or not ("n") out of the acclimation box of the apparatus, after five minutes of not exiting the acclimation box on its own. * choice: The light type chosen (i.e., responded to) by the individual. If the individual did not respond to / choose either of the provided light types, "none". * choice time (mm:ss): The amount of time that elapsed between opening the inner door of the acclimation box (allowing the individual access to the rest of the apparatus and therefore the opportunity to make a choice / respond to a provided light stimulus) and when the individual made a choice / responded to a provided light stimulus, in the format of mm:ss (minutes:seconds). If the individual did not respond to either light stimulus, "none". * choice time (min): Same as "choice time (mm:ss)", but in minutes only and in decimal form. #### File: petrel-openfield.csv **Description:** Raw data from our open field experiment to measure activity levels under various light spectra of stranded fledgling Leach's Storm-Petrels. ##### Variables * id: Unique identification number of each individual * treatment: Light type to which the individual was exposed during its 10-minute trial. "2700k" refers to warm white LED light; "5000k" refers to cool white LED light; "hps" refers to High Pressure Sodium light; and "dark" refers to darkness (i.e., no light provided). * timemobile_s: The amount of time spent mobile by the individual during its 10-minute trial, in seconds, as scored visually (i.e., by an observer watching the individual move in video footage). * totaltime_s: The trial duration, in seconds. Note that all trials were 10 minutes, or 600 seconds, in duration. #### File: petrel-openfield-audiovisual.csv **Description:** A comparison of visual versus aural scores of activity levels of stranded fledgling Leach's Storm-Petrels in video footage obtained during our open field test, in which we measured activity levels under various light spectra. For this comparison we used a random sample of a total of 10 trials in all treatments except "dark" (since visual scoring was not possible in darkness). The relationship between these two scoring methods was later used to develop a linear conversion equation applied to the aurally-scored "dark" treatment data for final analysis. ##### Variables * id: Unique identification number of each individual * treatment: Light type to which the individual was exposed during its 10-minute trial. "2700k" refers to warm white LED light; "5000k" refers to cool white LED light; "hps" refers to High Pressure Sodium light. * timemobile_visual_s: The amount of time spent mobile by the individual during its 10-minute trial, in seconds, as scored visually (i.e., by an observer watching the individual move in video footage). * timemobile_audio_s: The amount of time spent mobile by the individual during its 10-minute trial, in seconds, as scored aurally (i.e., by an observer listening to the individual move in the same video footage as that of "timemobile_visual_s"). ## Code/software Microsoft Excel or similar spreadsheet program ## Access information Other publicly accessible locations of the data: * None Data was derived from the following sources: * Not applicable