Thermal biology of African lovebirds and Australian grass parakeets

Burton, Steve; Perrin, M.R.; Downs, Colleen T.

doi:10.1016/j.jtherbio.2008.05.003

Cited by 3 publications

(2 citation statements)

References 44 publications

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“…Air temperature and relative humidity are expressed as absolute change while wind speed, solar radiation and rainfall are expressed as percent change needed to develop the budgerigar heat balance model were relatively few -the most important being its mass, shape, plumage depth, core body temperature range and basal metabolic rate. The first three morphological traits are easily measured, body temperature is highly phylogenetically conserved in birds [37], and metabolic rate scales predictably with body size [51] and body temperature [52]. The role of feathers in the heat transfer of birds is complex, especially with respect to the role of solar radiation [5].…”

Section: Inferring the Ecophysiology Of The Night Parrotmentioning

confidence: 99%

An estimate of the water budget for the endangered night parrot of Australia under recent and future climates

Kearney

Porter

Murphy

2016

Clim Chang Responses

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Background: Endangered species management must now incorporate the potential effects of climate change, but this is often in the context of limited data. The endangered night parrot was recently rediscovered in the Australian arid zone and a major effort is underway to ensure its survival. A key question is to what extent it is dependent on standing water under current and future climates, as this has major implications for understanding and managing its habitat requirements. However, very little is known about its ecology and physiology, and its conservation status precludes invasive ecophysiological studies. Method: Here we show how the methods of biophysical ecology permit strong inferences about this problem with minimal data. We developed a biophysical model of both the parrot and its habitat at the site of its rediscovery. We used allometrically-adjusted observations of the known physiology of a closely related desertadapted Australian parrot, the budgerigar, to infer unknown aspects of the night parrot's physiological responses, together with plumage measurements from museum specimens. We tested the microclimate model against empirical data on microhabitat temperatures and compared the endotherm model predictions against an infra-red thermograph of the bird itself. We then used the model to predict the frequency with which the parrot would need to find standing water under current and future climates depending on the water content of its food. Results: Our field data show that air temperature in night parrot roosts during high summer typically exceeds the inferred resting core temperature (38°C) and can exceed 45°C. Our calculations imply that night parrots can persist on dry seed during winter conditions without exceeding dangerous levels of dehydration, but would need access to water or succulent (55% water) food during summer. Air temperature at the site is projected to increase 3°C by 2070, which would lead to likely lethal (22% of body mass) levels of daily dehydration in some years even on succulent food, and would dramatically increase its dependence on standing water. Conclusion: Our findings have significant implications for the conservation management of the night parrot and provide guidance for future research priorities.

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Section: Inferring the Ecophysiology Of The Night Parrotmentioning

confidence: 99%

An estimate of the water budget for the endangered night parrot of Australia under recent and future climates

Kearney

Porter

Murphy

2016

Clim Chang Responses

View full text Add to dashboard Cite

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“…Parrots (order Psittaciformes) represent a major element in the avifauna of the vast arid interior of Australia, where these mostly diurnal birds cope with maximum summer air temperatures that may reach 47-52°C (Serventy, 1971). There is a long history of ecophysiological studies of metabolism and evaporative water loss in parrots, including a number of Australian species, but many of these studies were focused on thermoregulation at moderate T a within and below the thermoneutral zone (Burton et al, 2008;Dawson, 1965;Macmillen and Baudinette, 1993;Williams et al, 1991;Zungu et al, 2013), or designed to measure these parameters during exercise (Tucker, 1968). There have been fewer studies of metabolism and evaporative water loss in parrots at high T a (Dawson and Fisher, 1982;Greenwald et al, 1967;Weathers and Caccamise, 1975;Weathers and Schoenbaechler, 1976).…”

Section: Introductionmentioning

confidence: 99%

Avian thermoregulation in the heat: evaporative cooling capacity and thermal tolerance in two Australian parrots

McWhorter

Gerson

Talbot

et al. 2018

Journal of Experimental Biology

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Avian orders differ in their thermoregulatory capabilities and tolerance of high environmental temperatures. Evaporative heat loss, and the primary avenue whereby it occurs, differs amongst taxa. Although Australian parrots (Psittaciformes) have been impacted by mass mortality events associated with extreme weather events (heat waves), their thermoregulatory physiology has not been well characterized. We quantified the upper limits to thermoregulation under extremely hot conditions in two Australian parrots: the mulga parrot (; ∼55 g) and the galah (; ∼265 g). At air temperatures () exceeding body temperature (), both species showed increases in to maximum values around 43-44°C, accompanied by rapid increases in resting metabolic rate above clearly defined upper critical limits of thermoneutrality and increases in evaporative water loss to levels equivalent to 700-1000% of baseline rates at thermoneutral Maximum cooling capacity, quantified as the fraction of metabolic heat production dissipated evaporatively, ranged from 1.71 to 1.79, consistent with the known range for parrots, similar to the corresponding range in passerines, and well below the corresponding ranges for columbids and caprimulgids. Heat tolerance limit (the maximum tolerated) ranged from 44 to 55°C, similar to the range reported for passerines, but lower than that reported for columbids and caprimulgids. Our data suggest that heat tolerance in parrots is similar to that in passerines. We argue that understanding how thermoregulatory capacity and heat tolerance vary across avian orders is vital for predicting how climate change and the associated increase in frequency of extreme weather events may impact avian populations in the future.

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The influence of thermal tolerances on geographical ranges of endotherms

Khaliq

Böhning‐Gaese

Prinzinger³

et al. 2017

Global Ecol. Biogeogr.

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Aim To understand how climatic conditions influence the geographical distributions of species and their potential responses to climate change, we investigated the relationships between the thermal tolerances of species and the size and limits of their distributions. We tested two hypotheses for endotherms: the climatic variability hypothesis, which predicts increases in range size with increasing breadth of thermal tolerance, and the climatic extreme hypothesis, which predicts that range limits are related to thermal tolerance limits. Furthermore, we tested whether these relationships differ between temperate and tropical areas. Location Global. Time period Present. Major taxa studied Birds and mammals. Methods We compiled data on thermal tolerances that had been measured in physiological experiments for 453 endothermic species, along with information on geographical ranges and climatic conditions. We applied phylogenetic generalized least square regressions to test for relationships between thermal tolerance and (a) range size or limits and (b) breadth and extremes of the climatic conditions that each species experiences across its distribution. Results We found that range size was not related to the breadth thermal tolerance for endotherms. However, the range limits at high latitudes as well as the minimum temperatures experienced by species were closely related to the physiological cold tolerances of species. These relationships were particularly strong in temperate regions, but these patterns were not found in the tropics. Main conclusions Our results are inconsistent with the predictions of the climatic variability hypothesis, but are in line with the predictions of the climatic extreme hypothesis. Furthermore, the factors determining species distributions do not appear to be the same in tropical and temperate regions. Our study emphasizes the need to combine spatially explicit distribution models with information from physiological experiments in order to capture regional differences and improve predictions of the responses of species to climate change.

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Thermal biology of African lovebirds and Australian grass parakeets

Cited by 3 publications

References 44 publications

An estimate of the water budget for the endangered night parrot of Australia under recent and future climates

An estimate of the water budget for the endangered night parrot of Australia under recent and future climates

Avian thermoregulation in the heat: evaporative cooling capacity and thermal tolerance in two Australian parrots

The influence of thermal tolerances on geographical ranges of endotherms

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