Avian thermoregulation in the heat: resting metabolism, evaporative cooling and heat tolerance in Sonoran Desert songbirds
| Autor: | Eric Krabbe Smith, Andrew E. McKechnie, Alexander R. Gerson, Blair O. Wolf, Jacqueline O'Neill |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
030110 physiology
0301 basic medicine Thermotolerance Hot Temperature Physiology Aquatic Science Songbirds 03 medical and health sciences Respirometry Animal science biology.animal Animals Molecular Biology Ecology Evolution Behavior and Systematics biology Ecology Arizona Metabolism Thermoregulation biology.organism_classification Passerine Insect Science Basal metabolic rate Towhee Animal Science and Zoology Cactus wren Basal Metabolism Desert Climate Evaporative cooler Body Temperature Regulation |
| Zdroj: | The Journal of experimental biology. 220(Pt 18) |
| ISSN: | 1477-9145 |
| Popis: | We examined thermoregulatory performance in seven Sonoran Desert passerine bird species varying in body mass from 10 to 70g – Lesser Goldfinch, House Finch, Pyrrhuloxia, Cactus Wren, Northern Cardinal, Abert's Towhee and Curve-billed Thrasher. Using flow-through respirometry we measured daytime resting metabolism, evaporative water loss and body temperature at air temperatures (Tair) between 30° and 52°C. We found marked increases in resting metabolism above the upper critical temperature (Tuc), which for six of the seven species fell within a relatively narrow range (36.2° – 39.7°C), but which was considerably higher in the largest species, the Curve-billed Thrasher (42.6°C). Resting metabolism and evaporative water loss were minimal below the Tuc and increased with Tair and body mass to maximum values among species of 0.38 – 1.62 W and 0.87 – 4.02 g H2O hr−1. Body temperature reached maximum values ranging from 43.5° to 45.3°C. Evaporative cooling capacity, the ratio of evaporative heat loss to metabolic heat production, reached maximum values ranging from 1.39–2.06, consistent with known values for passeriforms and much lower than values in taxa such as columbiforms and caprimulgiforms. These maximum values occurred at heat tolerance limits (HTL) that did not scale with body mass among species, but were ∼50°C for all species except the Pyrrhuloxia and Abert's Towhee (HTL=48°C). High metabolic costs associated with respiratory evaporation appeared to drive the limited heat tolerance in these desert passeriforms, compared to larger desert columbiforms and galliforms that use metabolically more efficient mechanisms of evaporative heat loss. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|