DOI: 10.5061/dryad.zgmsbccnh
title: Data from: Parameters used in the endotherm biophysical model for each species

description: Climate change threatens biodiversity by compromising the ability to
 balance energy and water, influencing animal behaviour, species
 interactions, distribution, and ultimately survival. Predicting climate
 change effects on thermal physiology is complicated by interspecific
 variation in thermal tolerance limits, thermoregulatory behaviour, and
 heterogenous thermal landscapes. We develop an approach for assessing
 thermal vulnerability for endotherms by incorporating behaviour and
 microsite data into a biophysical model. We parameterised the model using
 species-specific functional traits and published behavioural data on
 hotter (maximum daily temperature, Tmax &gt; 35 °C) and cooler days
 (Tmax &lt; 35 °C). Incorporating continuous time-activity focal
 observations of behaviour into the biophysical approach reveals that the
 three insectivorous birds modelled here are at greater risk of lethal
 hyperthermia than dehydration under climate change, contrary to previous
 thermal risk assessments. Southern yellow-billed hornbills (Tockus
 leucomelas), southern pied babblers (Turdoides bicolor), and southern
 fiscals (Lanius collaris) are predicted to experience a risk of lethal
 hyperthermia on ~ 24, 65, and 40 more d y-1, respectively, in 2100
 relative to current conditions. Maintaining water balance may also become
 increasingly challenging. Babblers are predicted to experience a 57 %
 increase (to ~186 d yr-1) in exposure to conditions associated with net
 negative 24-hour water balance in the absence of drinking, with ~ 86 of
 those days associated with a risk of lethal dehydration. Hornbills and
 fiscals are predicted to experience ~ 84 and 100 d y-1 respectively
 associated with net negative 24-h water balance, with ≤ 20 of those days
 associated with a risk of lethal dehydration. Integrating continuous
 time-activity focal data is vital to understand and predict thermal
 challenges animals likely experience. We provide a comprehensive thermal
 risk assessment and emphasise the importance of thermoregulatory and
 drinking behaviour for endotherm persistence in the coming decades.
description: # Data from: Parameters used in the endotherm biophysical model for each
 species
 [https://doi.org/10.5061/dryad.zgmsbccnh](https://doi.org/10.5061/dryad.zgmsbccnh) ## Description of the data and file structure We provide a novel approach for assessing thermal vulnerability by incorporating detailed behaviour and microsite data for endotherms exposed to recent and future climates (RCP 8.5, 4.5) into a biophysical model. The model was parameterised using species-specific functional traits and published behavioural data on hotter (maximum daily temperature, *T*max &gt; 35 °C) and cooler days (*T*max &lt; 35 °C). Below we have provided the biophysical traits used in the parameterisation of the model, the customized endotherm model, the operative temperature model, and an example script for predicting thermoregulation in an exposed-on-ground microsite. We have noted below the sequence in which these scripts need to be run. ### Files and variables #### File: Model\_parameters.xlsx **Description:** Species-specific biophysical traits used to parameterise each model **Variable descriptions:** | Variable | **Description** | | :-------------------- | :------------------------------------------------------------------------------------------------------------------------------------- | | SHAPE | Ellipsoid shape | | TC (°C) | Target normothermic body temperature for optimal performance | | TC\_MAX (°C) | Maximum voluntary Tb before reaching potentially lethal Tb | | TC\_INC (°C) | Increments by which TC is increased | | ANDENS (kg/m3) | Body density | | DHAIR (m) | Feather diameter, set for ventral and dorsal sides respectively | | LHAIR (m) | Feather length, set for ventral and dorsal sides respectively | | ZFUR (m) | Plumage depth, set for ventral and dorsal sides respectively | | RHO (1/m2) | Plumage density, set for ventral and dorsal sides respectively | | REFL | Feather reflectivity (fractional, 0-1) | | SAMODE | Bird skin surface area allometry from Walsberg & King (1978) | | Q10 | Effect of Tb on metabolic rate when Tb &gt; core Tb | | QBasal (W) | Basal heat production | | DELTAR (°C) | Respiratory heating of breath, when Tb &gt; Tair. Otherwise, air leaving lunges was assumed to be the same as Tb. | | EXTREF | O2 extraction efficiency (%)d | | AK2 (W/mK) | Conductivity of fat | | AK1 & AK1\_MAX (W/mK) | Range of thermal conductivities of flesh. | | PCTBAREVAP (%) | Surface area for evaporation that is skin (i.e., bare skin, where cutaneous evaporation can occur) | | PCTWET (%) | Part of skin that acts as a free-water surface | | PCTWET\_MAX (%) | Maximum surface area acting as a free-water surface | | PCTWET\_INC (%) | Intervals by which skin wetness is increased | | PANT\_MAX | Maximum respiratory rate, defined as the multiplier on airflow through the lungs to simulate panting. Determined by metabolic rate. | | PANT\_MULT | Maximum possible increase in basal metabolic rate due to panting (i.e., 0.5 would result in 1.5 x BMR when panting is at the max value) | | PANT\_INC | Increment for a multiplier on breathing rate to simulate panting | ## Code/software The NicheMapR release relevant to this study (v3.0.0) and the endotherm component are both available via Zenodo (Kearney 2020). The codes provided are for general birds, and the species-specific models are available upon request. The scripts need to be run in order, starting with:  *EndoR_devel_customized.R* - This script adjusts the endoR_devel model to represent the general behavioural and physiological requirements of a bird in response to skin temperature. Thereafter the adjusted endotherm model was run with species-specific biophysical traits (e.g., body dimensions) and physiological responses (e.g., base skin wetness) (see Conradie et al., 2023 Table S1 for values used). *Operative temperature model.R* - This script runs the microclimate model for a specified height above ground at the location for which the bird behaviour data were collected. Thereafter, the microclimate model is passed through the ectotherm model to simulate operative temperature conditions. The ectotherm is set to 'dead' to disable metabolism and activity.  *Bird endotherm model using operative temperature.R* - After running the aforementioned scripts, this script predicts thermoregulation for a bird occupying a sun-exposed microsite. This is set for a hornbill, and the biophysical traits need to be adjusted using the Model_parameters.xlsx file for each species. The simulation is repeated for each of the other microsites (sun-off ground, shade-ground, shade-off ground). To do this the location needs to be updated in the operative temperature model script.  ### Usage notes **R** is required to open the scripts and depend on the NicheMapR and microclimate packages to be installed.