**Leading R script**, including data legends: Schabacker_etal_NN_OSF.Rmd This file contains the code for the primary analyses and figures of the study. Following reviewer comments we updated the R-script, leading to Schabacker_etal_NN_OSF_BEAS_R1_clean.Rmd **First supporting R script**: Schabacker_etal_isogeoloc.R This file contains the code for the isotopic geolocation to determine the migration strategy of each bat. **Second supporting R script**: Schabacker_etal_tripleisotope.R This file contains the code for the triple isotope approach in support of the single isotope approach. **Key to variables**: **Exploration Analysis** • Observation.number = Unique observation (assay) identifier • Individual = Unique individual identifier • Replicated = Indicator of whether the respective bat has been tested twice • UA = Length of the lower arm (in mm) • Weight = Weight of the bat (in grams) on the day of the exploration assay • BodyCondition = Weight / UA • Date = Date of the exploration assay and fur sample collection • DayYear = Day of the year on which the exploration assay and fur sample collection was conducted • SunsetTime = Time of day the sun set • StartTime = Is time on a 24 hr scale (hh:mm:ss) at which the exploration assays was started • MintoSunset = Start time of the assay converted to minutes relative to sunset (negative values are before sunset) • Tobs = Environmental temperature during the exploration assay • Direction = The direction the emergence tube was facing (N,E,S,W) • Test = First or second exploration assay • EL_head = Latency of the head emerging into the novel environment (in seconds). Bats that did not emerge were assigned the maximum value + 1 (181) • EL_body = Latency of more than half of the body emerging into the novel environment (in seconds). Bats that did not emerge were assigned the maximum value + 1 (181) • EmergenceDuration = Time between head and body emergence. Bats that did not emerge were assigned the maximum value + 1 (181) • NoRooms = Total number of rooms visited in the two minutes after body emergence • UniqueRooms = Number of unique rooms visited in the two minutes after body emergence • TotalCalls = Total number of echolocation calls emitted by the subject • NrCalls.before.BodyE.= Number of echolocation calls emitted by the subject before body emergence • NrCalls.after.BodyE.= Number of echolocation calls emitted by the subject after body emergence for two minutes • Sneezes = Number of air puffs emitted during the assay • Headpokes = Total number of times the bat poked its head in another room **Stable Isotope Analysis** • Observation.number = Unique observation (assay) identifier • Individual = Unique individual identifier • Date = Date of the exploration assay and fur sample collection • Location = Location of assay and sampling • Species = Species name (scientific) • SIA.Nr = Unique stable isotope analysis sample identifier • Remarks = Explanation for missing values • d2H = H isotope value • dN = N isotope value • dC = C isotope value • Migrant = Migrant assignment based on dH values using Isorix and supported (95%) with triple-isotope approach (H,N,C)