DOI: 10.5061/dryad.msbcc2g9k
title: Data from: Migratory routing and departure decisions of <em>Porzana carolina</em> (Sora): New insights from the Motus Wildlife Tracking System

description: During migration, birds make a variety of decisions that may impact their
 overall survival and fitness. These decisions include, but are not limited
 to, their overall migration route as well as their departure timing,
 considering variable weather conditions. Understanding how birds make
 these decisions can provide insight into not only their general migration
 strategy but also the constraints they face on
 migration. Unfortunately, the migratory ecology of many members
 of the Rallidae family remains poorly documented, leaving a critical gap
 in the migration literature. From 2017 to 2022, we fitted 202
 Soras (Porzana carolina) with transmitters at Jug Bay, a critical stopover
 site along the Patuxent River, Maryland, USA, and tracked their migratory
 movements and decisions using the Motus Wildlife Tracking System. Tracking
 data revealed a tendency to follow the Atlantic coast in the fall. Spring
 migrants took variable paths, with routes primarily to the Great Lakes
 region, but also had shorter stopovers. We also determined the atmospheric
 conditions under which Soras initiated migration. Rising atmospheric
 pressure 24 hours before departure increased departure likelihood, as did
 wind profit (favorable tailwinds), while increased cloud cover
 had reduced departure probability, possibly due to disrupted nighttime
 navigation. It also emphasizes the importance of continued research with
 advanced tracking technologies to better understand the dynamics of
 extended stopovers.
description: # Data from: Migratory routing and departure decisions of *Porzana
 carolina* (Sora): New insights from the Motus Wildlife Tracking System
 Dataset DOI: [10.5061/dryad.msbcc2g9k](10.5061/dryad.msbcc2g9k) ##
 Description of the data and file structure This dataset investigates the
 departure routes and decisions of Sora (*Porzana carolina*) during their
 fall and spring migrations. Birds were trapped using modified Seth-Lowe
 Clover Leaf traps along the Patuxent River in Maryland from 2017-2022.
 Sora were fitted with Lotek nano tags and tracked via the Motus Wildlife
 Tracking System. We examine the atmospheric conditions that inform the
 departure decisions of these birds, as well as detail some of the most
 commonly used migratory pathways. ### Files and variables #### File:
 SORA-tag-detections-raw-rm-dep.rds **Description:** Raw, uncleaned
 detection data across the Motus Network of Soras tagged at Patuxent River
 Park. Further documentation of variables can be found at motus.org.  ####
 File: motus-sex-predict.csv **Description:** Dataset of Sora captured and
 fitted with a transmitter at Patuxent between 2017 and 2022. This data
 includes morphometric and age data completed at the time of banding. NAs
 may be present in the data if that particular variable was not measured at
 the time of banding.  ##### Variables * FID: Row ID * tagID: Tag Number *
 mfgID: Manufacturer's ID.  * tagDeployID: Tag deployment ID.  *
 speciesID: Species numerical code from Motus Data) * speciesName: Latin
 name of the species tagged * bandNumber: Aluminum Band Number. Band
 provided by USGS Bird Banding Laboratory.  * markerNumber: Number of any
 other identifying markers (e.g. tag number). * sex: Initial sex assignment
 in the field upon capture * age: Adult (ad) or Juvenile (juv, imm).
 Assigned based on plumage characteristics.  * weight: Weight at capture
 (g) * wing: Wing Cord Measurement (mm) * Tar: Tarsus measurement (mm).
 Variable used to help determine sex * Cul: Measurement of exposed Culmen
 (mm). Variable used to help determine sex.  * bill: length of the bill in
 mm (if measured). * head: head and bill length in mm (if measured) *
 fatScore: Amount of fat bird accumulated (if measured) * predict.sex:
 score from 0-1 based on morphometric model detailed in Dami et al. 2024. 
 * sex2: Sex assignment based on morphometric models.  * agree.field: Does
 the initial field assignment match the sex assignment based on
 morphometric model #### File: sora-departures.csv \**Description: ** 
 ##### Variables * motusTagDepID: Unique identifier for each individual
 bird. Combination of the Motus Tag ID and the Motus Deployment ID. *
 migration: Migration in which detection occurs (spring vs. fall) * season:
 Season in which the detection occurs. Combination of a migration and a
 year (i.e. Fall 2018). * tagDeployStart: Date/Time motus Tag was deployed
 * location.lat: Latitude of location (degrees) * location.long: Longitude
 of location (degrees) * start.date: Time monitoring started/ tag
 deployment time. * depart.date: Eventual departure date of bird tagged on
 stopover * Date: Date of monitoring for departure. * depart.event:
 Indicates departure event. Binomial variable (0 or 1). 1 indicates that
 the departure occurred while 0 means that the bird did not depart. *
 depart.time: Departure date and time as timestamp in UTC. * start: The
 beginning of the time interval. The first interval starts at 0 for each
 subject and indicates the day of capture for most individuals. * end: The
 end of the time interval. * depart.day.of.year: Day of year in which
 eventual departure occurred * sex2: Sex assigned based on morphometric
 model from Dami et al. 2024. Binomial outcome. Male (M) or Female (F). *
 Age: Age class of birds. Juvenile (Hatch-Year) or Adult (After-Hatch Year)
 * u10_component: U component of wind (m/s). This data was acquired via the
 European Centre for Medium-Range Weather Forecast's ERA5 Single-Level
 Dataset. * v10_component: V component of wind (m/s). Data acquired via
 ERA5 Single-Level Dataset. * s.pressure: measure of weight of air
 contained in vertical column above the Earth's surface
 (Pa)** **Downloaded from ERA5-Single Level. * cloud.cover: Proportion of
 sky hidden by visible clouds (0-1). Downloaded from ERA5-Single Level
 Datasets. * total.precip: Accumulate liquid and frozen water (mm) that
 falls onto the earth’s surface in a one-hour period. Downloaded from
 ERA5-Single Level Datasets. * wind.speed: Wind speed (m/s) derived from u
 and v component of wind. * tailwind: The wind profit (m/s) experienced by
 birds based on an individual birds target direction. Calculated using the
 u and v wind components as well as the departure bearing of the bird. *
 pressure.diff: Overall net change in s.pressure. * pressure.trend: Hourly
 pressure change (Pa/hour) over 24 hours. Defined as pressure.diff divided
 by 24. ## Code/software RDS files can be read into Program R, a free
 software for statistical computing (R Core Team 2024;
 [https://www.r-project.org](https://www.r-project.org)). Motus data can be
 downloaded directly from R using the motus package
 ([https://motuswts.github.io/motus/articles/02-installing-packages.html](https://motuswts.github.io/motus/articles/02-installing-packages.html)). Departure decisions analysis were implemented using the "survival" package in R. Other packages for analysis and data manipulation include: DBI # connecting with SQLite databases RSQLite # for working with SQLite databases tidyverse # for data manipulation lubridate # for working with dates sf # mapping. rnaturalearth # mapping ggplot2 tidyverse suncalc # calculating sunrise and sunset times.  ## Access information This study utilizes environmental and movement data sourced from public repositories and collaborative networks. Atmospheric data (ERA5) was obtained from the **Copernicus Climate Data Store (CDS)** under Creative Commons Attribution 4.0 International (CC-BY 4.0). Movement data was retrieved from **Movebank** (Study ID: 1457748657) and the **Motus Wildlife Tracking System** (Project ID: Project 172). Data from Movebank is used in accordance with the license as specified by the data owners. Motus data access was granted under the Motus Data Use Policy and through collaboration with the respective project investigators. Other publicly accessible locations of the data: Motus Project #172 ([https://motus.org/data/project?id=172](https://motus.org/data/project?id=172)) Movebank ID: 1457748657 Data was derived from the following sources: ERA-5 Single Levels ([https://cds.climate.copernicus.eu](https://cds.climate.copernicus.eu))