DOI: 10.5061/dryad.kd51c5bkn
title: Data from: Wintering closer to breeding grounds comes at a cost in an Arctic-specialized songbird, <em>Plectrophenax nivalis</em> (Snow Bunting)

description: Wintering at high latitudes may offer Arctic-breeding migratory birds
 advantages such as shorter migration distances and earlier arrival at
 breeding sites, potentially improving reproductive success. However,
 wintering at northern sites may also come at a cost as birds can
 experience colder and harsher conditions than individuals wintering
 further south, consequently requiring physiological adjustments for life
 in the cold. We compared the physiological costs of wintering at different
 latitudes in Plectrophenax nivalis (Snow Buntings) from an Eastern
 Canadian population during the peak of winter. We hypothesized that
 individuals wintering at higher (i.e., colder) latitudes would be
 structurally larger, have better thermal insulation, maintain thicker
 pectoralis muscles and more lean tissues, carry larger lipid reserves, and
 experience greater physiological maintenance costs compared to individuals
 wintering at lower (i.e., warmer) latitudes. Contrary to our expectation,
 structural size did not differ between wintering sites. However, northern
 birds were 8% heavier and carried 32% more lipid reserves, suggesting
 increased energy storage for cold endurance. These birds also had 4% more
 lean mass and maintained slightly thicker pectoralis muscles, consistent
 with greater shivering thermogenesis capacity. Notably, basal metabolic
 rate (BMR), corrected for lean mass, was 6% higher in northern birds,
 indicating elevated physiological maintenance costs in colder
 environments. These findings therefore show that P. nivalis must pay a
 significant and measurable cost when wintering in colder
 environments to benefit from the potential fitness advantage of a shorter
 migration distance to their Arctic breeding grounds. Our study illustrates
 the physiological trade-off migratory birds face when selecting wintering
 locations and underscores the importance of considering both ecological
 benefits and metabolic costs when studying avian life-history strategies
 under variable climatic conditions.
description: # Data from: Wintering closer to breeding grounds comes at a cost in an
 Arctic-specialized songbird, *Plectrophenax nivalis* (Snow Bunting)
 Dataset DOI: [10.5061/dryad.kd51c5bkn](10.5061/dryad.kd51c5bkn) ##
 Description of the data and file structure Data was collected between
 January 19, 2023, and February 23, 2023, in Quebec and Ontario, Canada.
 ### Files and variables #### File: Metadata_data_climate.docx
 **Description:** Metadata of data_climate.csv #### File:
 Metadata_data_buntings.docx **Description:** Metadata of data_buntings.csv
 #### File: data_buntings.csv **Description:** Physiological and
 morphological data obtained on a wild population of snow buntings
 (*Plectrophenax nivalis*) during the months of January and February of
 2023. Commas are used as a decimal delimiter. NA means "Not
 available" and is used when the variable was not measured or the
 value is missing from the files. ##### Variables * Bird_ID: unique
 individual identification * Date_capture_std: date of capture in Julian
 day * Time_capture_std: time of capture in decimal time *
 Region_2: division of regions as “north” or “south” * Latitude: latitude
 of capture sites in decimal degrees * Longitude: longitude of capture
 sites in decimal degrees * Transport_min: duration of transportation
 between capture site and field laboratories in minutes * Sex: sex of
 individuals * Age: age of individuals. SY = second year, ASY = after
 second year * Beak: total culmen length in millimetres *
 Head_Beak: measurement from the tip of the culmen to the back of the head
 in millimetres * Tarsus: minimum tarsus length measured from the
 inter-tarsal joint to toe joint in millimetres * Wing: unflatten wing
 length measured from the carpal joint to the tip of the longest primary
 feather in millimetres * Tail : tail length measured from the base of the
 tail to the tip of the longest feather in millimetres *
 Body_mass_capture: body mass measured directly after capture in grams *
 Time_QMR_std: time at which QMR measurements are performed in decimal time
 * Time_QMR_captivity: duration of captivity before QMR measurements are
 performed in minutes * Body_mass_QMR: body mass before QMR measurements
 are performed in grams * Mean_Fat: mean of 3 to 4 measurements of lipid
 mass measured with QMR in grams * Mean_Lean: mean of 3 to 4 measurements
 of lean mass measured with QMR in grams * Ultrasound: indicates if
 ultrasound measurements are performed on an individual or not *
 Time_Ultrasound_std: time at which the ultrasound measurements are
 performed in decimal time * Time_Ultrasound_captivity: duration of
 captivity before ultrasound measurements are performed in hours *
 Keel_length_1_mm: keel length (1/4) measured by ultrasound in millimetres
 * Keel_length_2_mm: keel length (2/4) measured by ultrasound in
 millimetres * Keel_length_3_mm: keel length (3/4) measured by ultrasound
 in millimetres * Keel_length_4_mm: keel length (4/4) measured by
 ultrasound in millimetres * Mean_keel_lenght_mm: mean of 3 to 4
 measurements of keel length measured by ultrasound in millimetres *
 Pectoral_muscle_1_mm: pectoralis muscle thickness (1/4) measured by
 ultrasound in millimetres * Pectoral_muscle_2_mm: pectoralis muscle
 thickness (2/4) measured by ultrasound in millimetres *
 Pectoral_muscle_3_mm: pectoralis muscle thickness (3/4) measured by
 ultrasound in millimetres * Pectoral_muscle_4_mm: pectoralis muscle
 thickness (4/4) measured by ultrasound in millimetres *
 Mean_pectoral_muscle_mm: mean of 3 to 4 measurements of pectoralis muscle
 thickness measured by ultrasound in millimetres *
 Conductance_Done: indicates if conductance trials are performed on an
 individual or not * Date_conductance_std: date at which conductance trials
 are performed in Julian day * Time_body_mass_before_conductance_std: time
 at which the body mass is measured before the conductance trials are
 performed in decimal time * Body_mass_before_conductance: body mass before
 conductance trials are performed in grams * Tb_before_conductance: body
 temperature measured before conductance trials are performed in degrees
 Celsius * Body_mass_after_conductance: body mass after conductance trials
 are performed in grams * Tb_after_conductance: body temperature measured
 after conductance trials are performed in degrees Celsius *
 StartTime_VO2_conduc_std: = time at which fractional oxygen concentration
 (VO2) is measured at its lowest during conductance trials in decimal time
 * Fasting_time_conduc: fasting time before VO2 is measured during
 conductance trial in hours * Time_conduc_captivity: duration of captivity
 before VO2 is measured during conductance trials in hours *
 Time_conductance_captivity_before_trial: duration of captivity before
 conductance trials start in hours * VO2_watt_cond: VO2 measurements during
 conductance trials in watt * Temperature_Ch_cond:temperature inside the
 metabolic chambers during conductance trials in degrees Celsius *
 Conductance_watt: conductance measurements in watt * BMR_done: indicates
 if basal metabolic rate (BMR) trials are performed on an individual or not
 * Date_BMR_std: dates at which BMR trials are performed in Julian day *
 Start_time_BMR_std: time at which BMR trials begin in decimal time *
 Time_body_mass_before_BMR_std: time at which the body mass is measured
 before the BMR trials are performed in decimal time *
 Body_mass_before_BMR: body mass before BMR trials are performed in grams *
 Time_body_mass_after_BMR_std: time at which the body mass is measured
 after the BMR trials are performed in decimal time *
 Body_mass_after_BMR: body mass after BMR trials are performed in grams *
 StartTime_BMR_VO2_std: time at which fractional oxygen concentration
 (VO2)is measured at its lowest during BMR trials in decimal time *
 Fasting_time_BMR: fasting time before VO2 is measured during BMR trial in
 hours * Time_BMR_captivity: duration of captivity before BMR trials start
 in hours * VO2_watt_BMR: VO2 measurements during BMR trials in watt *
 Temperature_Ch_BMR: temperature inside the metabolic chambers during BMR
 trials in degrees Celsius #### File: data_climate.csv
 **Description:** Temperature data from weather stations close by capture
 sites. Commas are used as a decimal delimiter. ##### Variables *
 Date_capture: date of temperature measurements in dd/mm/yyyy *
 Date_std: date of temperature measurements in Julian day *
 Region_2: division of regions where weather stations are located as
 “north” or “south” * Longitude: longitude of weather stations in decimal
 degrees * Latitude: latitude of weather stations in decimal degrees *
 STATION_NAME: weather station names as provided by Environment and Climate
 Change Canada (ECCC) weather office online and ministère de
 l’Environnement, de la Lutte contre les changements climatiques, de la
 Faune et des Parcs (MELCCFP) * MIN_TEMPERATURE: minimum daily ambient
 temperatures in degrees Celsius * MEAN_TEMPERATURE:mean daily ambient
 temperatures in degrees Celsius #### File:
 Turcotte_et_al_Buntings_analyses.Rmd **Description:** R Markdown provided
 to perform statistical analyses if needed. ## Code/software R Software is
 required to read the R Markdown file provided. All packages used for
 statistical analyses are presented in the R Markdown. ## Access
 information Temperature data was derived from the following sources: *
 Environment and Climate Change Canada (ECCC) weather office online *
 Ministère de l’Environnement, de la Lutte contre les changements
 climatiques, de la Faune et des Parcs (MELCCFP)