Snow bunting respirometry data

1. Arctic animals inhabit some of the coldest environments on the planet and have evolved physiological mechanisms for minimizing heat loss under extreme cold. However, the Arctic is warming faster than the global average and how well Arctic animals tolerate even moderately high air temperatures (Ta) is unknown.

2. Using flow-through respirometry we investigated the heat tolerance and evaporative cooling capacity of snow buntings (Plectrophenax nivalis; ≈ 31g, N = 42), a cold specialist, Arctic songbird. We exposed buntings to increasing Ta and measured body temperature (Tb), resting metabolic rate (RMR), rates of evaporative water loss (EWL) and evaporative cooling efficiency (the ratio of evaporative heat loss to metabolic heat production).

3. Buntings had an average (±SD) Tb of 41.3 ± 0.2 °C at thermoneutral Ta, and increased Tb to a maximum of 43.5 ± 0.3 °C. Buntings started panting at Ta of 33.2 ± 1.7 °C, with rapid increases in EWL starting at Ta = 34.6 °C, meaning they expe...