How to avoid errors when quantifying thermal environments

Abstract

Summary 1.Modelling thermal environments at high resolution becomes simpler when using operative temperature, which condenses microclimate and morphology into an index of thermal stress. Operative temperature can be mapped using large numbers of 'operative temperature thermometers', hollow models that duplicate external properties of the animal. 2. As climatologists predict that air will warm by 2-4°C by 2100, biologists must be able to distinguish climate change from systematic errors in operative temperature of the same magnitude. 3. A systematic error in operative temperature of 2°C or a similar amount of climate warming can change predicted surface activity and indices of habitat quality, thermoregulatory precision and predation risk by 5-12%, and in some cases more than 30%. 4. As construction details of operative temperature thermometers can affect their accuracy by 2°C or more, biologists should use detailed physical models calibrated against living animals over potential ranges of postures, orientations and microclimates. 5. Water-filled models do not measure operative temperature correctly, fail to capture thermal extremes and are an unnecessary complication as one can easily compute the body temperature of moving or stationary animals from body mass and the spatio-temporal distribution of operative temperatures.

Thermal-safety margins and the necessity of thermoregulatory behavior across latitude and elevation

“…Evaporation provides a physiological cooling mechanism (13): Wet-skin T e,max , even in the full sun, allows almost as much reduction in T e,max as shade-use (Fig. 4), compensating almost entirely for radiative heat gain as long as hydration is possible (18).…”

Can behaviour buffer the impacts of climate change on an arid-zone bird?

“…The environmental temperature (heat load or thermal challenge) experienced by a Southern Fiscal on a perch is also an integration of all of these factors, but additionally includes rates of heat transfer via evaporative water loss and input from metabolic heat production (Bakken et al 1985). Furthermore, the shape and posture of a living bird and the properties of its plumage also affect the environmental temperature it experiences in any given location (Bakken et al 1985;Bakken and Angilletta 2014). Bakken et al (1985) found that the correlation between environmental temperatures recorded by taxidermic mounts of Red-winged Blackbirds Agelaius phoeniceus and a matched-size blackbulb thermometer had an r 2 value of 0.968.…”

Evolutionary stasis and lability in thermal physiology in a group of tropical lizards

“…colour, shape and size; [46]). We embedded iBUTTON data loggers (DS1921K Maxim) into copper models shaped using a mould of A. cybotes-this new generation of copper models permits automated temperature recording (for details of their construction, see [47]). Methods for calibrating the copper models are given in the electronic supplementary material.…”