This README.txt file was generated on 2020-11-19 by Martyna Syposz Weather_Data_DataDyard.csv Ð file includes the weather data for each day of the experiment. 1. Number of variables: 9 2. Number of cases/rows: 131 3. Variable List: Date Ð the date of the experiment in dd/mm/yyyy format Time_BST Ð the time (British Standard Time) when a measurement of cloud cover, wind direction and speed was taken. Cloud_8 Ð the cloud cover measured in a scale from 0-8 (0 being clear and 8 being completely opaque) by an observer. Wind_direction Ð the wind direction measured in 16 cardinal directions. Wind_speed_avg_kt Ð the wind speed measured in knots (average over a minute). Wind_MAX_kt Ð the maximum wind speed measured in knots. Magnetic Ð the colour of LED (red, green or blue) that was assigned to the magnetic group for a night. Please, note that in 2019, we did not have the magnetic group. Control Ð the colour of LED (red, green or blue) that was assigned to the control group for a night. Please, note that in 2019, we alternated between blue and green LEDs in the control treatment. Location Ð the location of the experiment. The experiment was undertaken on Skomer Island in two locations, Skomer Head and Pigstone Bay. Observation_Data_DataDyard.csv Ð file includes the orientation of Manx shearwaters taken during the experiments. 1. Number of variables: 7 2. Number of cases/rows: 1019 3. Variable List: Date Ð the date of the experiment in dd/mm/yyyy format Time_BST Ð the time (British Standard Time) when an orientation was recorded. Treatment Ð the treatment of an individual bird. Birds in the magnetic treatment had a rare-earth magnet in a box on top of their head, whereas control birds had a glass bead. Colour Ð the colour of an LED light attached to a birdÕs back. Please, note that each group (control and magnetic) had one colour of LEDs assigned to them during a single night. The treatment was blind to observers at the time of the experiment. Van Ð the bearing of a bird. In 2018 and 2019, the bearing of a bird was taken every 10 sec. NAs indicate the starting point of a bird. Birds were followed with binoculars up until they disappear from the observerÕs view. In 2017, only the last bearing was recorded. BirdID Ð the consecutive number, changing with each observed bird. Location Ð the location of the experiment (Skomer Head or Pigstone Bay).