DOI: 10.5061/dryad.zw3r228fn
title: Data from: Migratory herbivorous waterfowl track multiple resource waves during spring migration

description: East Asian herbivorous waterfowl intensively use farmland in spring, next
 to their natural habitat. Accordingly, they might have expanded their
 migration strategy from merely tracking the green wave of newly emerging
 vegetation to also incorporating the availability of post-harvest
 agricultural seeds (here dubbed the seed wave). However, if and how
 waterfowl use multiple food resources to time their seasonal migration is
 still unknown. We test this migration strategy using 167 spring migration
 tracks of five East Asian herbivorous waterfowl species and mixed-effect
 resource selection function models. We find all study species arrive at
 their core stopover sites in the Northeast China Plain after agricultural
 seeds become available, extend their stay after spring vegetation emerges,
 and arrive at breeding sites around the emergence of vegetation. At the
 core stopover sites, all study species use snowmelt as a cue to track seed
 availability, although smaller-bodied species tend to arrive later. At the
 breeding sites, swans track the onset of vegetation emergence and geese
 track the mid or end phrases of snowmelt. Our findings suggest that
 waterfowl track multiple resource waves to finetune their migration,
 highlighting new opportunities for conservation.
description: # Migratory herbivorous waterfowl track multiple resource waves during
 spring migration This work analyzes satellite tracking data of five
 migratory herbivorous waterfowl species in East Asia to investigate if and
 how herbivorous waterfowl track multiple resource waves during spring
 migration. ### Description of data and file structure: **R Scripts:** *
 **01 - Analyzing migration parameters.R:** R script that reads in the
 output of identified sites (calculated in SaTScan) and calculates
 migration parameters. * **02 - Investigating resource utilization in
 migration.R:** R script that analyses habitat use intensity on farmlands
 and natural habitats across time, and investigates habitat switch before
 and after the emergence of vegetation at core stopover sites in the
 Northeast China Plain. * **R scripts 03-06:** **Determine the bird arrival
 and resource availability relationship.** 03 - Testing differences in
 resource and migration timing.R: R script that shows resource and
 migration timing, and tests differences between the resource and migration
 timing in different regions for each species. 04 - Resource selection
 function models.R: R script that executes models for each of five
 herbivorous waterfowl species in two regions. 05 - Estimate optimal lags
 on resource availability.R: R script that reads in output of the model and
 estimates optimal lags on food availability/snowmelt conditions. 06 -
 K-fold cross-validation.R: Cross-validation on the resource selection
 models. 06b - K-fold.r: The source file input '06 - K-fold
 cross-validation.R' to run cross-validation. #### Data: **Metadata**
 14 .csv files are included. (1) siteinfo: identified wintering, stopover,
 and breeding sites * **species** = abbreviated names of five herbivorous
 waterfowl species (GWFG, LWFG, TUBG, TS, SG) * **track** = the identity of
 each track (track ID), named as BirdsID_Year * **BirdsID** = the identity
 of each individual * **Year** = the year of the track * **CLUSTER** = the
 identity of identified sites for each track using the space-time
 permutation model in SaTScan * **LATITUDE** = latitude of the site *
 **LONGITUDE** = longitude of the site * **RADIUS** = radius of the site
 (unit: km) * **START_DATE** = Date of bird arrival at a stopover site *
 **END_DATE** = Date of bird departure from a stopover site * **start** =
 bird arrival - convert the date format into 'day of year' format
 * **end** = bird departure - convert the date format into 'day of
 year' format * **site** = site types (Wintering, Stopover, Breeding)
 (2) PheEvents: Data used to generate Figure 2 * **phe** = the phenological
 events 15 groups are included in this column: win_SOS, win_departure:
 vegetation emergence, departure at wintering sites ncp_25, ncp_50, ncp_75,
 ncp_100, ncp_SOS, ncp_arri, ncp_depar: 25%, 50%, 75%, 100% relative seed
 availability, vegetation emergence, arrival, departure at core stopover
 sites bre_25, bre_50, bre_75, bre_100, bre_SOS, bre_arri: 25%, 50%, 75%,
 100% snowmelt, vegetation emergence, arrival at breeding sites * **Day** =
 timing of phenological events (shown as day of year) (3) WeeklyHabitatUse:
 Data used to generate Figure 3 * **doy** = day of bird occurrence *
 **habitat** = Foraging habitat types (Farmlands, Natural -
 Grass/Shrub/Wetlands) * **percen_lc** = Proportion of land cover in use at
 daytime * **week** = week of bird occurrence (e.g., week 1 means 1-7 days
 of the year) (4) HabitatSwitchNCP: Data used to investigate habitat switch
 before and after the emergence of vegetation in the Northeast China Plain
 and generate Figure S14 * **group** = during two different time windows
 ('Before'-from bird arrival to the emergence of vegetation;
 'After'-from the emergence of vegetation to departure) Tables
 (5) - (14): Input of resource selection function models. Data used to
 generate Figure 4, Figure S15, Table 1, Table S10 by R scripts 04-06.
 Table names: ncp_plant, ncp_x25, ncp_x50, ncp_75, ncp_100:  datasets for
 core stopover sites in the Northeast China Plain bre_plant, bre_x25,
 bre_x50, bre_75, bre_100: datasets for breeding sites Columns in tables: *
 **select** = presence and absence (1-presence; 0-absence) * **Daysto** =
 the number of days between resource availability/snowmelt and the bird
 arrival date.