DOI: 10.5061/dryad.x95x69pr6
title: Reduced hybrid survival in a migratory divide between songbirds

description: 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.
description: ## 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))