High-latitude night shortening forces birds to accept increasingly diurnal migration to maintain flight duration
Creators: name: Sivakumar, Ashwin
name: Sheldon, Daniel
name: Horton, Kyle
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 310301
subject: Behavioural ecology
classificationCode: 310203
subject: Computational ecology and phylogenetics

description: Authors: Ashwin H. Sivakumar*, Daniel Sheldon, Kyle G. Horton*<br>Affiliations: 1. Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA https://orcid.org/0000-0001-9628-37512. College of Information and Computer Sciences, University of Massachusetts, Amherst, MA, USA 3. Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, USA*Corresponding author, asivakumar@college.harvard.edu, kyle.horton@colostate.edu<br><br>***File descriptions***alaska_data.csv - this file contains the processed radar reflectivity data from Sivakumar et al. (2021), spanning 7 radar stations in Alaska between 1995 to 2018, which was used for our analyses. Each row represents a separate scan (scans are collected every 10 minutes during clear conditions and every 5 minutes during periods of precipitation). The columns are as follows:- file: contains a unique identifier for the scan- linear eta: a linear reflectivity estimator calculated according to a procedure described in Chilson et al. (2012), averaged across all vertical profile bins in the scan.- linear eta sum: the same estimator, summed across all vertical profile bins.- u: the east-component of the calculated radial velocity.- v: the north-component of the calculated radial velocity.- uwnd: the east-component of the local wind vector- vwnd: the north-component of the local wind vector- headingu: east-component of the true heading vector, derived through subtraction of the wind vector from the radial velocity.- headingv: north-component of the true heading vector, derived through subtraction of the wind vector from the radial velocity. -nsamples: the number of available vertical profile bins for the scan<br>alaska_script.Rmd - loads all outputs and statistics provided in the main manuscript and data supplement. Set working directory to this folder before running. <br>nexrad_site_list_with_utm.csv - this file contains all NEXRAD Level II sites in the United States. Each row represents a different site. The columns are as follows:- SITE: Name of station- AGENCY: Agency operating station- CITY: Closest city to station- STATE: State containing station- UTM_N: Universal Transverse Mercator latitudinal coordinate of station- UTM_E: Universal Transverse Mercator longitudinal coordinate of station- LATITUDE_N: Latitudinal coordinate of station- LONGITUDE_W: Longitudinal coordinate of station, in degrees W- BASE_HT_M: Elevation above sea level of tower in meters- TOWER_HT_M: Height of tower above base- ANT_HT_M: Height of antenna above sea level in meters<br>alaska.prj, alaska.shp, alaska.shp - shapefiles necessary to generate a map of Alaska. <br>Figure S1 - Temporal distribution of available radar scans from the seven NEXRAD stations across subarctic Alaska. All scans are from between 1995 and 2018; the gap in the data between 2004 and 2013 corresponds to an absence of radar data from Alaska in the NOAA archive from this period. <br>Figure S2 - Average diurnal cycle in migratory activity (quantified by reflectivity) centered at local dusk across all days throughout the fall and spring migratory periods at each of the seven stations across Alaska, with the cycle corresponding to each station color-coded by longitude. <br>Figure S3 - Average diurnal cycle in migratory activity (quantified by reflectivity) centered at local dusk across all days throughout the fall and spring migratory periods at each of the seven stations across Alaska, with the cycle corresponding to each station color-coded by latitude. <br>Figure S4 - Hour after dusk of peak migratory activity (η) for each sampling period versus night length. Fitted line and 95% confidence interval (R^2 = 0.023, p&lt;0.001) are from a least-squares linear model. <br>Figure S5 - Duration between the 5th and 95th quantile of migratory activity (η) within each sampling period versus night length. Fitted line and 95% confidence interval (R^2 = 0.054, p&lt;0.001) are from a least-squares linear model. <br>