DOI: 10.5061/dryad.b2rbnzspx
title: Data from: Sex-specific tradeoffs influence thermoregulation under climate change

description: Increasingly, climate change is pushing species to the limits of their
 thermal tolerance, with cascading effects across ecosystems. Animals use
 behavior to prevent these harmful physiological states, but their need and
 ability to do so varies with their traits. Within species, traits like sex
 and reproductive status affect heat sensitivity, perhaps eliciting
 differences in behavioral responses to thermal extremes. We evaluated
 whether sex and reproductive status affected thermoregulatory behavior and
 its efficacy in moose (Alces alces), a heat-sensitive endotherm that
 relies on thermal refuge. We expected traits associated with elevated heat
 load would be linked to heightened selection for thermal refuge and that
 differences in selection would successfully alleviate differing risks of
 overheating. Thus, reproductive females and males, who are more
 heat-sensitive, would have stronger selection for thermal refuge than
 non-reproductive females. We assessed selection of thermal refuge at bed
 sites and generated biophysical models to evaluate if selection mitigated
 risk of overheating. Reproductive status did not elicit differences in
 selection by females. The sexes, however, differed in selection of the
 tradeoff between solar cover and cooling from wind. Females selected
 refuge with canopy cover and avoided wind. Males did not select cover and
 had weaker avoidance of wind than females. Yet, both sexes were more
 likely to overheat in areas of low cover, even if wind speeds were high.
 Hence, males had weaker selection of refuge than females despite being
 more likely to overheat, and life history tradeoffs failed to explain the
 sub-optimal thermoregulatory behavior. We identify sex-specific
 thermoregulatory tradeoffs, highlighting the disproportionate effects of
 climate change on certain demographic groups. Moreover, we emphasize the
 relevance of trait-based approaches for studying changing ecosystems.
description: <strong>Capture and Handling</strong>
 We used a helicopter to chemically immobilize adult moose (≥ 1
 year) each year in March (2020–2023; Levine et al. 2022a). For the
 duration of the study, we aimed to maintain a sample size of 15 collared
 animals per sex. Males were captured once, and females were recaptured
 annually. We removed the right, incisiform canine (Swift et al. 2002) and
 determined age via cementum annuli (Matson’s Laboratory, Milltown, MT). We
 estimated body mass using morphometrics (Hundertmark and Schwartz 1998).
 To assess nutritional condition, we measured the maximum depth of rump fat
 using a portable ultrasound device (Ibex Pro, E.I. Medical Imaging,
 Loveland, Colorado) with a 5-MHz linear-array transducer (Stephenson et
 al. 1998) and accompanied ultrasound with palpation to determine a body
 condition score (Levine et al. 2022b). We derived percent ingesta-free
 body fat (hereafter nutritional condition) from scaled rump fat (Cook et
 al. 2010; Stephenson et al. 1998) and body condition score (Levine et al.
 2022b). Nutritional condition of cervids in late winter is highly
 correlated with condition throughout summer (Monteith et al. 2013). We
 checked pregnancy status with transrectal ultrasonography (Stephenson et
 al. 1995). We fitted pregnant females with vaginal implant transmitters
 and deployed GPS collars with hourly fix rates on all moose (VERTEX PLUS
 Collar; Vectronic Aerospace GmBH, Berlin, Germany).
 <strong>Field Observations</strong>
 We assessed reproductive status of females by monitoring juvenile
 presence through observation (10 May–15 August). Within 48 h of vaginal
 implant expulsion, we observed females to determine neonate presence
 (detected or not detected), status (dead or alive in birth site), and
 number. We located females every 2-weeks throughout the summer to search
 for the juvenile. If a juvenile was not detected, we performed two
 additional searches to confirm the non-detection represented juvenile
 loss. Females were considered reproductive while the juvenile was present
 and non-reproductive when a juvenile was not observed for 2 consecutive
 visits Thus, following juvenile mortality, a female could switch in
 classification from reproductive to non-reproductive.
 <strong>Bed Sites</strong> During
 the summers of 2021 and 2022, we identified bed sites used by collared
 moose between parturition (mid-May) and growth of winter pelage
 (September) using mean location of clustered (≤15 m apart) GPS-collar
 fixes (Verzuh et al. 2021). We censored GPS data to 3-D or 2-D fixes and
 dilution of precision &lt;2 (D’Eon and Delparte 2005; Moen et al.
 1997). Sites were limited to beds used for 1+ h during daylight hours
 (i.e., sunrise to sunset at the site). We visited bed sites within 2 weeks
 of use. We confirmed bed sites by searching a 15m radius for signs of use:
 matted vegetation, muddy depressions, faecal matter, or moose hair. For
 each confirmed bed site (i.e., used site), we assessed three available
 sites at a randomly generated azimuth (0° to 359°) and distance (15 to
 330m; Verzuh et al. 2021) from the used site. To
 collect microclimate data at used and available sites, we placed weather
 stations at the centre of the bed (Kestrel Instruments 5500 Weather Meter,
 Boothwyn, PA). The weather stations were on tripods 30 cm off the ground
 with a rotating mount, wind vane, and shaded temperature logger. The
 stations collected temperature, wind speed, and relative humidity at 5 min
 intervals. We deployed weather stations in new locations each day for the
 hours of the day the bed site was used by the moose. We assessed other
 attributes relevant to thermal conditions at all sites including canopy
 cover, landcover type, vegetation density, and soil moisture (Verzuh et
 al. 2021). We measured canopy cover at 25% increments with a densitometer
 (Graphic Resource Solutions, Arcata, CA, U.S.A.) at the four corners of
 the bed site and averaged values to get mean percent canopy cover. We
 selected landcover type based on predominant habitat: conifer, riparian,
 sagebrush, meadow, agricultural, alpine, aspen, and talus. We later
 combined rare landcover classes (alpine, talus, and agricultural) and the
 common sagebrush class into a single ‘dry open’ classification to be used
 as a reference category. To assess soil moisture, we qualitatively
 classified dry (0%), moist (25%), or wet soil (75%), and used 2.5 cm as
 the lower limit for standing water (100%; NRCS 1998). We estimated
 vegetation density (i.e., horizontal cover) up to the height of a bedded
 moose (0.75 m) in the immediate vicinity of the bed as either sparse
 (0–10% cover), open (11–60% cover), or dense (61–100% cover). Soil
 moisture and vegetation density were modelled as continuous for ease of
 interpretation.
description: # Data from: Sex-specific tradeoffs influence thermoregulation under
 climate change During the summers of 2021 and 2022, we identified bed
 sites used by collared moose between parturition (mid-May) and growth of
 winter pelage (September) using mean location of clustered (≤15 m apart)
 GPS-collar fixes (Verzuh et al. 2021). We censored GPS data to 3-D or 2-D
 fixes and dilution of precision &lt;2 (D’Eon and Delparte 2005; Moen et
 al. 1997). Sites were limited to beds used for 1+ h during daylight hours
 (i.e., sunrise to sunset at the site). We visited bed sites within 2 weeks
 of use. We confirmed bed sites by searching a 15m radius for signs of use:
 matted vegetation, muddy depressions, faecal matter, or moose hair. For
 each confirmed bed site (i.e., used site), we assessed three available
 sites at a randomly generated azimuth (0° to 359°) and distance (15 to
 330m; Verzuh et al. 2021) from the used site. To collect microclimate data
 at used and available sites, we placed weather stations at the centre of
 the bed (Kestrel Instruments 5500 Weather Meter, Boothwyn, PA). The
 weather stations were on tripods 30 cm off the ground with a rotating
 mount, wind vane, and shaded temperature logger. The stations collected
 temperature, wind speed, and relative humidity at 5 min intervals. We
 deployed weather stations in new locations each day for the hours of the
 day the bed site was used by the moose. We assessed other attributes
 relevant to thermal conditions at all sites including canopy cover,
 landcover type, vegetation density, and soil moisture (Verzuh et al.
 2021). We measured canopy cover at 25% increments with a densitometer
 (Graphic Resource Solutions, Arcata, CA, U.S.A.) at the four corners of
 the bed site and averaged values to get mean percent canopy cover. We
 selected landcover type based on predominant habitat: conifer, riparian,
 sagebrush, meadow, agricultural, alpine, aspen, and talus. We later
 combined rare landcover classes (alpine, talus, and agricultural) and the
 common sagebrush class into a single ‘dry open’ classification to be used
 as a reference category. To assess soil moisture, we qualitatively
 classified dry (0%), moist (25%), or wet soil (75%), and used 2.5 cm as
 the lower limit for standing water (100%; NRCS 1998). We estimated
 vegetation density (i.e., horizontal cover) up to the height of a bedded
 moose (0.75 m) in the immediate vicinity of the bed as either sparse
 (0–10% cover), open (11–60% cover), or dense (61–100% cover). Soil
 moisture and vegetation density were modelled as continuous for ease of
 interpretation. ## Description of the data and file structure Data are in
 two csv files. One has data for all study animal beds and one has data for
 study animal beds in which nutritional condition and body size data were
 also available for that year. Columns in each csv have the same
 definitions, described below. *Denotes columns only present in condition
 csv. Cluster - Animal and date of bed use for generalized estimating
 equation Stratum - Grouping term for bed site hour and associated random
 site hours Used - Used or random site DateUsed - Date animal used the bed
 Sex - Sex of animal (FEMALE or MALE) Calf - Calf status of animal (TRUE,
 FALSE, or NA for males) Habitat - Habitat type at site Veg - Vegetation
 density at site (%) Soil - Soil moisture at site (%) CanopyAvg - Average
 canopy cover at site (%) MaxTemp - Maximum hourly temperature at site (°C)
 MaxHum - Maximum hourly humidity at site (%) MaxWind - Maximum hourly wind
 speed at site (m/s) AnimalAge - Age of animal (years) *BodyLengthTail -
 Body length of animal in March prior to summer of data collection (cm)
 *IFBFat - Body fat in March prior to summer of data collection (%) ##
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