DOI: 10.5061/dryad.12jm63z90
title: Flexibility in the face of climate change? A rapid and dramatic shift toward later spring migration in Hudsonian godwits (Limosa haemastica)

description: With rapid environmental change, shifts in migration timing are vitally
 important for maintaining population stability in migratory species and
 have been widely documented. However, little remains known about how
 migrants make these shifts and what factors influence the utilization of
 these strategies, limiting our ability to assess their vulnerability to
 climate change. Hudsonian godwits (Limosa haemastica) are an extreme
 long-distance migratory shorebird that (1) have previously shifted their
 population-level migration timing and (2) are sexually dimorphic. We
 combined over a decade of tracking data from one breeding population with
 a historical predictive model to assess on-going shifts in migration
 timing and investigate potential sex-specific migration strategies. We
 found that godwit departure and arrival timing shifted 6 days later from
 2010-2023 with no differences in timing between the sexes. The population
 maintained an average migratory duration of 24 days and drove shifts in
 arrival timing entirely by changing their nonbreeding ground departure.
 Yet, we also found that godwits arrived later than predicted by the
 historical model, indicating this response may not be adaptive. These
 results emphasize the urgent need for a more holistic approach to
 assessing the vulnerability of migratory species and the adaptiveness of
 changes in migration timing.
description: # Flexibility in the face of climate change? A rapid and dramatic shift
 toward later spring migration in Hudsonian godwits (Limosa haemastica)
 Dataset DOI: [10.5061/dryad.12jm63z90](10.5061/dryad.12jm63z90) ##
 Description of the data and file structure We deployed light-level
 geolocators on Hudsonian godwits breeding in Beluga, Alaska, USA, during
 two time periods, 2009-2012 and 2020-2023. We analyzed the resulting
 movement trajectories of those geolocators to assess whether there were
 changes in the nonbreeding ground departure and breeding ground arrival
 timing of individuals and the population over time. ### Files and
 variables #### File: 2009-2012\_Tags.csv **Description:** Migratory timing
 data from the first period of geolocator deployment ##### Variables * Flag
 code: Individual Identifier * Time period: Year deployed and year
 recovered * Year: Actual year of migratory timing data * USGS_Band:
 Individual Identifier * Sex: Individual's sex based on plumage *
 Multi year? Y/N: Did the geolocator contain multiple years of data * Con
 file?: Individual identifier on wet/dry data file * Bel_Arri: Breeding
 Ground Arrival Date * Con_Bel_Arri: Breeding Ground Arrival Date derived
 from Wet/Dry Data * Chi_Dept: Nonbreeding Ground Departure Date *
 Con_Chi_Dept: Nonbreeding Ground Departure Date derived from Wet/Dry Data
 #### File: Data\_Final.csv **Description:** Combined geolocator data
 across both time periods. ##### Variables * Flag code: Individual
 Identifier * Time period: Year deployed and year recovered * Year: Actual
 year of migratory timing data * USGS_Band: Individual Identifier * Sex:
 Individual's sex based on plumage (M/F) * Multi year? Y/N: Did the
 geolocator contain multiple years of data * Con file?: Individual
 identifier on wet/dry data file * Bel_Arri: Breeding Ground Arrival Date *
 Con_Bel_Arri: Breeding Ground Arrival Date derived from Wet/Dry Data *
 Chi_Dept: Nonbreeding Ground Departure Date * Con_Chi_Dept: Nonbreeding
 Ground Departure Date derived from Wet/Dry Data * Duration: Migratory
 Duration (Unit: Days) * E/L: Early (2009-2012) or Late (2020-2023) period
 #### File: Predicted\_Beluga\_Arrival\_Dates\_2011-2023.csv
 **Description:** Predicted arrival dates for Hudsonian Godwits to Beluga,
 Alaska, USA, derived from a historical statistical model. ##### Variables
 * Year: Year of prediction * x: Predicted Arrival Date (Unit: Day of Year)
 #### File: Multitrack\_allyears.csv **Description:** Migratory timing data
 for individuals tracked across multiple years ##### Variables * Flag code:
 Individual Identifier * Time period: Early (2009-2012) or Late (2020-2023)
 * Year: Year During Which Data was Collected * YrNum: Year of Study During
 Which the Data Was Collected (2010 = 1) * Yrseq: Standardized Value for
 Year of Study * MnYr: The Mean Standardized Year Value for an Individual *
 YrDiff: Difference Between First and Last Year for Which an Individual Had
 Data * USGS_Band: Individual Identifier * Sex: Sex of Individual (M/F) *
 Multi year? Y/N: Did the geolocator contain multiple years of data
 (Yes/No) * Con file?: Name of Wet/Dry Data File * Bel_Arri: Breeding
 Ground Arrival Date * Con_Bel_Arri: Breeding Ground Arrival Date derived
 from Wet/Dry Data * Chi_Dept: Nonbreeding Ground Departure Date *
 Con_Chi_Dept: Nonbreeding Ground Departure Date derived from Wet/Dry Data
 #### File: Godwit\_Arrival\_Date\_Data\_2011-2023.csv
 **Description:** Values to be used to predict Hudsonian Godwit arrival
 dates to Beluga, Alaska, using the historical statistical model #####
 Variables * Year: Year of arrival at the breeding grounds * Actual:
 Observed arrival date based on eBird data (Unit: day of year) *
 Anc_Prev_May: Mean May Temperature from the Previous May in Anchorage, AK
 (Unit: Degrees Celsius) * Anc_5yr: Average Mean May Temperature from
 Anchorage, AK across the previous 5 years (Unit: Degrees Celsius) *
 Hou_Apr_Wind: Mean April Wind Speed in Houston, TX (Unit: km/hr) *
 PMC_Precip: Total Precipitation from Puerto Montt, Chile (Unit: mm) *
 Prev_Arrival: Breeding Ground Arrival Date from the Previous Year (Unit:
 Day of Year) * SOI_Mar: Southern Oscillation Index Value from Australia
 (Unit: Unitless) #### File: Godwit\_Arrival\_Date\_Data\_1974-2010.csv
 **Description:** Data used to parameterize the historical statistical
 model ##### Variables * Year: Year of Observation * Julian_Date: Julian
 Date of Breeding Ground Arrival Date (Unit: Day of Year) *
 Anc_Prev_May: Mean May Temperature from the Previous May in Anchorage, AK
 (Unit: Degrees Celsius) * Anc_5yr: Average Mean May Temperature from
 Anchorage, AK across the previous 5 years (Unit: Degrees Celsius) *
 Hou_Apr_Wind: Mean April Wind Speed in Houston, TX (Unit: km/hr) *
 SOI_Mar: Southern Oscillation Index Value from Australia (Unit: Unitless)
 * PMC_Precip: Total Precipitation from Puerto Montt, Chile (Unit: mm) *
 Prev_Arrival: Breeding Ground Arrival Date from the Previous Year (Unit:
 Day of Year) **Note:** There is an 'NA' (not available) in the
 column "Prev_Arrival" for 1974. This is because arrival date
 data began being collected in 1974 and, therefore, no previous arrival
 date data exists for before 1973. #### File:
 HUGO\_FinalModels\_Script\_Apr.r **Description:** Migratory timing data
 for a single individual Hudsonian Godwit that was tracked with a
 geolocator across the entire study period (2009-2023) #### File:
 1PJ\_late.csv **Description:**  ##### Variables * Flag code: Individual
 Identifier * Time period: Early (2009-2012) or Late (2020-2023) * Year:
 Year of Observation * USGS_Band: Individual Identifier * Sex:
 Individual's Sex based on Plumage (M/F) * Multi year? Y/N: Did the
 geolocator contain multiple years of data * Con file?: Name of Wet/Dry
 Data File * Bel_Arri: Breeding Ground Arrival Date * Con_Bel_Arri:
 Breeding Ground Arrival Date derived from Wet/Dry Data * Chi_Dept:
 Nonbreeding Ground Departure Date * Con_Chi_Dept: Nonbreeding Ground
 Departure Date derived from Wet/Dry Data ## Code/software All codes for
 our analyses are included in the file
 "HUGO_FinalModels_Script_May.r"