DOI: 10.5061/dryad.v41ns1s71
title: Data from: Drivers of spring migration phenology in Rocky Mountain elk

description: By migrating, ungulates take advantage of cyclical fluctuations in
 resources, which allows them to persist at greater population numbers than
 they would in the absence of these seasonal movements. We sought to
 identify the drivers of spring elk (Cervus canadensis) migration and
 evaluate how well individuals were able to optimize access to forage prior
 to departure, while migrating, and upon arrival on summer range.
 Specifically, we investigated the timing and duration of spring migration
 in four Colorado elk herds to test how forage quality and snow dynamics
 pre-, during, and post-migration influenced elk departure from winter
 range and the length of time spent migrating. Our analyses revealed
 significant heterogeneity among and within herds. Overall, spatiotemporal
 dynamics in forage and snow emerged as critical drivers influencing
 migratory phenology, but the discrete covariates associated with forage
 and snow were herd-specific. We did not find marked sub-strategies wherein
 some herds or individuals optimized a specific component of migration, but
 rather found that elk varied in their ability to optimize access to forage
 at all times analyzed. Our findings suggest that elk exhibit a flexible
 response to environmental cues, adjusting migration timing and duration in
 accordance with local conditions. These results contribute to a deeper
 understanding of the mechanisms driving ungulate migration and emphasize
 the importance of considering dynamic environmental factors in studies of
 migration phenology. Further, they emphasize the importance of forage
 conditions not just on the migratory route, but also on winter and summer
 range. Additionally, they provide baseline knowledge of elk migrations in
 Colorado, useful information for ensuring the conservation and persistence
 of these migratory routes and the productivity they facilitate.
description: # Data from: Drivers of spring migration phenology in Rocky Mountain elk
 [https://doi.org/10.5061/dryad.v41ns1s71](https://doi.org/10.5061/dryad.v41ns1s71) ## Description of the data and file structure Crews, S., N. D. Rayl, M. W. Alldredge, E. J. Bergman, C. R. Anderson Jr., G. Bastille-Rousseau. Drivers of spring migration phenology in Rocky Mountain elk. Scientific Reports. Crews-elk-migration-phenology.csv file with 147 rows and 13 columns. Rows contain covariate information for 147 individual elk-years relating to phenological metrics associated with spring migration events in 4 herds in and around Colorado, USA, tracked from 2017 2022. The file contains columns with the unique elk-year identifier (ID), the herd of the elk-year (Herd; herds are designated by their Colorado Parks and Wildlife Data Analysis Unit: E15 = Avalanche Creek, E2 = Bears Ears, E33 = Trinchera, E20 = Uncompahgre Plateau), the year that individual was collared (FieldSeason), the straight-line Euclidean distance of the individuals spring migration in kilometers (Distance), the duration of the spring migration in days (Duration), the day-of-year (DOY) of the departure from winter range (Start_Date; note that these generally correspond to the same year as the FieldSeason except in cases where the following years spring migration was instead used due to data availability, in which case the DOY is corrected to align with the year of the migration in question and not the collaring year), the DOY of the summer range arrival (End_Date), the mean DOY of peak instantaneous rate of green-up (IRG) prior to departure from the winter range (mean_peak_irg_prior), the mean DOY of peak IRG in the migratory corridor (mean_peak_irg_corr), the mean DOY of peak IRG following arrival at the summer range (mean_peak_irg_after), the mean snow-free DOY prior to departure from the winter range (snowfree_prior), the mean snow-free DOY in the migratory corridor (snowfree_corr), and the mean snow-free DOY following arrival at the summer range (snowfree_after).