## thrush\_juvenile\_morphology.csv Morphological phenotypes from juvenile Swainson's thrushes. Data were collected in the field from birds banded and tagged with individual tracking devices. All birds were caught in British Columbia in a hybrid zone formed between inland and coastal subspecies of Swainson's Thrush. * reference: individual ID associated with sequences uploaded to SRA * release_site: description of site where bird was tagged and released * release_year: year bird was caught * tag_type: type of tracking tag. "radio" = motus radio tag * sex_binary: 0 = male, 1 = female; based on Z and W sequences * age_release: HY = hatch year * release_gps.n: bird release latitude, in degrees north * release_gps.w: bird release longitude, in degrees west * motustagid: ID associated with individual tracking data, available at motus.org * band: individual bird banding number * tarsus.length: length of tarsus, in mm * fat.score: visual assessment of fat, lower values indicate less fat * tail.length: length of tail, in mm * wing.cord: length of full wing, in mm * kipps: Kipp's distance, in mm * distal: distal wing length, in mm * carpal: carpal wing length, in mm * p7: p7 feather length, in mm * p8: p8 feather length, in mm * p9: p9 feather length, in mm * p10: p10 feather length, in mm * bander: initials of person banding bird, HJ = Hannah Justen, KD = Kira Delmore ## tag\_detection\_data.xlsx Individual tracking data from juvenile and adult Swainson's thrushes. Data were collected in the field from birds banded and tagged with individual tracking devices. Some individuals were tagged with archival trackers (GPS tags and light-level geolocators) and some were tagged with Motus radio tags. ### thrush\_meta\_240104 Metadata associated with tagged individuals * name_in_vcf = individual ID in vcf file * reference = individual ID on fastq files * release_site = location bird was tagged and released * release_year = year bird was tagged and released * tag_type = type of tag (archival or radio) * sex_binary = sex - 1 (male) or 0 (female) * age_release = age bird was tagged and released - HY (hatch year), AHY (after hatch year), SY (second year), or ASY (after second year) * release_gps.n = latitude where bird was tagged and released * release_gps.w = longitude where bird was tagged and released * motustagid = ID associated with motus tag * band = bird banding number ### 2.filtered\_data\_Jul\_1 Motus tag detections dataset * motusTagID = ID associated with motus tag * runID = ID associated with the run of tag detections * ts = time and date of detection * tsCorrected = Julian date of detection * runLen = measure of detection reliability; number of tag bursts detected by receiver * tagProjID = ID associated with our motus project (#280) * mfgID = tag manufacturer ID * mfg = tag manufacturer name * tagModel = code associated with Lotek tag model * tagLifespan = tag battery life, in days * pulseLen = tag radio wave pulse, in seconds * tagDeployID = ID number associated with Lotek tag * speciesID = ID number associated with study species * tagDeployStart = time and date tag was deployed * tagDeployEnd = expected time and date of tag deployment end * tagDepLat = latitude tag was deployed * tagDepLon = longitude tag was deployed * fullID = full motus ID associated with project and tag deployment batch * recvDeployID = receiver station ID * recvDeployLat = receiver latitude * recvDeployLon = receiver longitude * recv = ID code associated with receiver * recvDeployName = receiver name * recvSiteName = site name for receiver * isRecvMobile = is receiver mobile - binary (0 = no) * recvProjID = ID associatd with receiver motus project * speciesEN = species name in English * speciesFR = species name in French * speciesSci = species scientific name * speciesGroup = species taxonomic name * tagProjName = name of radio tag project * recvProjName = name of receiver project * detectyear = year of detection * detectdoy = day of the year of detection; 1 = Jan1, 365 = Dec 31 * detecttime = time of detection * reference = individual reference in fastq files and banding sheets * release_site = site where bird was tagged * name_in_vcf = individual name in vcf file ### adults\_recaptured\_2023 List of adults recaptured in 2023 breeding season * geolocator = ID for geolocator attached to individual * banding_# = banding number of banded individual ### survival\_data\_motus\_by\_latitude Collated banding sheet data for adults recaptured prior to 2023 * name_in_vcf = individual name in vcf file * release_site = site where bird was taggged * release_year = year bird was tagged * tag_type = type of tag (archival or radio) * sex_binary = sex - 1 (male) or 0 (female) * retrieved_archival = binary; was the bird retrieved - y (yes) or n (no) * age_release = age bird was tagged and released - HY (hatch year), AHY (after hatch year), SY (second year), or ASY (after second year) * release_date = date bird was tagged and released * release_GPS.N = latitude where bird was tagged and released * release_GPS.W = longitude where bird was tagged and released * date_recaptured = date bird was recaptured * band_. = banding number of banded individual ## Description of May 2024 updates Addition of a new excel file (tag_detection_data.xlsx) that contains Swainson's thrush radio tag detection data and archival tag recapture data used in the publication. These data correspond to publicly available analysis pipelines located on GitHub (04_survival_cleaning.R in [github.com/stephblain/thrush_hybrid_survival/](https://github.com/stephblain/thrush_hybrid_survival/tree/main))

Migratory divides, hybrid zones between populations that use different seasonal migration routes, are hypothesized to contribute to speciation. Specifically, relative to parental species, hybrids at divides are predicted to exhibit intermediate migratory behavior and reduced fitness as a result. We provide the first direct test of the second prediction here with one of the largest existing avian tracking datasets, leveraging a divide between Swainson’s thrushes where the first prediction is supported. Using detection rates as a proxy for survival, our results supported the migratory divide hypothesis with lower survival rates for hybrids than parental forms. This finding was juvenile-specific (vs. adults), suggesting selection against hybrids is stronger earlier in life. Reduced hybrid survival was not explained by selection against intermediate phenotypes or negative interactions among phenotypes. Additional work connecting specific features of migration is needed, but these patterns provide strong support for migration as an ecological driver of speciation.