Data File Name: BTO-Blue-Tits-Great-Tits-Coal-Tits-Records.xlsx

Original Article: Long-term declines in winter body mass of tits throughout Britain and Ireland correlate with climate change, Furness, Euan, Robinson, Rob

Data location in Dryad: doi:10.5061/dryad.1d21m78

Contact: Euan Furness, enf21@cam.ac.uk

File type: xlsx Excel File

Analysis in R 3.5.1: https://www.r-project.org/

Ring Number: Number, unique to each individual in the analysis, here anonymised to protect individual ringers.

Species: British name for the individual's species.

BTO Age Code: British Trust for Ornithology code for the age of the bird at capture. See:
https://www.bto.org/sites/default/files/u17/downloads/about/resources/agecodes.pdf

Sex: Sex of bird. U = unsexed, M = male, F = female

Month: Month of capture. 1 = January

Year: Year of capture.

Time: Decimal time of capture (i.e. faction of the day that has passed at time of capture. e.g. 0.5 = noon).

Wing Length: Wing length of the bird at capture. (mm)

Weight: Body mass of the bird at capture. (g)