Data from: Breeding site departure and post-departure movement strategy in Vireo olivaceus (Red-eyed Vireo)
Data files
Aug 07, 2025 version files 37 KB
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Horn_et_al_2025_data.csv
34.53 KB
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README.md
2.47 KB
Abstract
Few studies have been able to assess the decision-making process behind migratory departures from the breeding site and the extent to which extrinsic cues that favor departure from fall stopover sites also apply to initial departure from breeding sites. Factors influencing departure may vary between species that first make short-distance regional movements vs. those that immediately begin long-distance migration, but for most migratory songbirds, it is unknown which post-departure movement strategy they use or why. We used an automated radio telemetry network to track adult male Vireo olivaceus (Red-eyed Vireo) as they departed their northwest Pennsylvania breeding site on fall migration to determine their post-departure movement strategy. We also assessed how local weather conditions, including surface pressure, humidity, precipitation, and wind, influenced the probability of departing the breeding site on fall migration. For the individuals for whom we could confidently ascertain departure day and time, 86% departed during the first 2 hr after sunset. Net displacement was positive, and birds headed directly south towards Florida. Birds were more likely to depart on nights with rising surface pressure and high humidity, and frequently departed in unsupportive wind conditions (headwinds). Our results suggest that V. olivaceus initiates true long-distance migratory flights after departing from its breeding sites. Birds may have departed under unsupportive wind conditions due to the scarcity of tailwinds at the breeding site. Alternatively, birds leaving their breeding areas in the fall may be less selective of optimal weather conditions for departure than birds departing stopover habitats, as they have higher fuel loads and ample time to compensate during the rest of their migratory journey.
Dataset DOI: 10.5061/dryad.8sf7m0d27
Description of the data and file structure
Weather variables influencing migratory departure decisions for 22 Red-eyed Vireos.
Files and variables
File: Horn_et_al_2025_data.csv
Description: Dataset for Cox proportional hazards models to assess how weather variables influence the probability of birds departing the breeding site on fall migration.
Variables
- ID: tag number for each bird
- status: 0= did not depart, 1=departed
- year: 2020 or 2021
- detect.date: dates during the migratory period that each bird did not depart, up until their actual departure date
- detect.time: time of migratory departure
- start.time: start time for Cox model calculation
- end.time: end time for Cox model calculation
- depart.day.of.year: day of year that each individual departed on migration
- surface.pressure.trend: surface pressure trend in the 24 hr prior to departure (Pa/hr)
- average.relative.humidity: average relative humidity in the 3 hr prior to departure (%)
- wind.profit: wind profit at the hour of departure
- wind.profit.class: wind profits greater than 0.5 were classified as ‘tailwinds’, those less than -0.5 were classified as ‘headwinds’, and middle values were classified as ‘minimal winds’
- rain.class: when the rate of precipitation in the hour of departure was less than 0.5 mm, it was classified as ‘trace or no precipitation’, with anything higher being classified as ‘rain’
Access information
Other publicly accessible locations of the data:
- All Red-eyed Vireo detection data from the Motus Wildlife Tracking System (Project 326) are available at www.motus.org
Data was derived from the following sources:
- Hourly weather measurements for the breeding site were retrieved from the ERA5-Land dataset (Muñoz-Sabater et al. 2021). Weather variables used in the models were transformed using the original hourly weather measurements (as per the methods text in Horn et al. 2025) and thus are derived values from the ERA5-Land dataset. CDS catalogue entry: Copernicus Climate Change Service (C3S)(2019): ERA5-Land hourly data from 1950 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). DOI: 10.24381/cds.e2161bac (Accessed 2024)