**Citation** File upload includes: "Metadata.csv": metadata file with detail on tagged individuals. Headers explained below. SpeciesCN = species common name. "Common guillemot" SpeciesLN = species latin name. "Uria aalge" Colony = name of breeding colony DeploymentID = a combination of the year when the tags were retrieved and the geolocator-immersion logger number; format "yyyy_nnnn" ID = individual ID (BTO number) TDR_ID = time-depth recorder logger number GLS_ID = geolocation-immersion logger number DeployDate = date and time loggers were deployed; format: "dd/mm/yyyy hh:mm:ss" RetrieveDate = date and time logger was retrieved; format: "dd/mm/yyyy hh:mm:ss" DeployLat = latitude of breeding colony where tag was deployed DeployLon = longitude of breeding colony where tag was deployed GLSFailDt = date the geolocation-immersion logger failed (if applicable); format: "dd/mm/yyyy hh:mm:ss" TDRFailDt = date the time-depth recorder logger failed; format: "dd/mm/yyyy hh:mm:ss" FailDate = earliest fail date across both loggers; format: "dd/mm/yyyy hh:mm:ss" FailReason = whichever logger failed first, or if GLS was lost LoggerData = useable logger data: Both/TDR/Exclude Feathers = Yes/No whether a feather sample was taken "ColonyPoints.csv": locations of breeding colonies Colony = name of breeding colony lon = longitude lat = latitude "PopulationKernels.shp": 50% kernel density contours for each colony and month Colony = name of breeding colony Month = month (July - March) "IndividualKernels.shp": 50% kernel density contours for individual for which we had feather isotope data during post-breeding moult TDR_ID = time-depth recorder logger number Colony = name of breeding colony "Isotopes.csv": isotope data for each individual (if included in isotope analysis) Colony = name of breeding colony TDR_ID = time-depth recorder logger number Isotope = delta 15N value of the secondary feather (ppm) Isoscape = mean delta 15N value extracted from the UK Isoscape within the individual's 50% kernel density contour during post-breeding moult Difference = difference between the isotope and isoscape values (isotope - isoscape) "IDZ.csv": proportion of dives within the intra-depth zone for each foraging bout. Each row is a foraging bout. Colony = name of breeding colony TDR_ID = time-depth recorder logger number Date = date of foraging bout; format: "yyyy-mm-dd" nIDZDives = number of dives with maximum depth within 10% depth of the maximum depth of the previous dive nDives = number of dives in the foraging bout PIDZDives = proportion of dives within the intra-depth zone "Behaviours.csv": combined logger data and initial behaviours (before leg-tucking has been equalised between the legs). Each row is a TDR reading Colony = name of breeding colony TDR_ID = time-depth recorder logger number Date = date; format: "yyyy-mm-dd" lon = longitude lat = latitude GLSTime = date-time of the GLS activity data reading; format: "dd/mm/yyyy hh:mm" TDRTime = date-time of the TDR reading; format: "dd/mm/yyyy hh:mm" GLSWetDry = wet/dry of the GLS. Max = 200 TDRDepth = depth recorded by the TDR GLSTemp = temperature recorded by the GLS (when immersed in salt water) TDRTemp = temperature recorded by the TDR TDRTempFlucs = fluctuations between rows of TDR temperatures LightLevel = time of day: Day/Night/Twilight SST = mean daily temperature of GLS (if available) or TDR during TDR-wet activities if not Behaviour = behavioural classificiation. One of: Dive/Active/Inactive/Flight/Colony DiveNo = unique numeric ID for each dive bout MaxDepth = maximum depth recorded within each dive bout "ActivityBudget.csv": daily time in activity budgets for each individual, plus energetic costs. Colony = name of breeding colony TDR_ID = time-depth recorder logger number Date = date; format: "yyyy-mm-dd" Behaviour = behavioural classificiation. One of: Dive/Active/Inactive/Flight/Colony Hours = daily time in each behaviour (hours) Expenditure = energetic cost of time in behaviour "A16XXX_dd-mm-yyyy.csv" 45 files - raw TDR data from CEFAS Rows 1 - 380 are information about the tag and summary data From row 380 - 385: details about data block From row 386-7206, raw data within data block 1. Then follows a break and information about the next data block, before the next chunk of raw data begins. This continues until end. Raw data format: Time Stamp = date and time of logger reading; format: "dd/mm/yyyy hh:mm" Pressure = numerical pressure value Temp = numerical temperature value All spatial projections are in lat-long: EPSG:4326