Albedo and Thermal Ecology of White, Red, and Black Cows (Bos taurus) in a Cold Rangeland Environment

SIMPLE SUMMARY: There is a trend of more black hided beef cattle globally, yet cattle on rangelands have limited thermoregulation options. I measured the winter albedo of cows in fresh snow with pixel analysis (n = 3 images) and then external cattle temperatures (Temp(cow)), and the differences (ΔT) between Temp(cow) and ambient air temperature (Temp(amb)) of 638 Temp(cow) × Temp(amb) combinations for white (n = 183), red (n = 158), and black (n = 297) Bos taurus females. Cattle were free roaming extensive Wyoming, USA rangelands along a broad thermal gradient (≈−33 °C to +33 °C) from 2016 to 2018. Albedo differed for white, red, and black cows (0.69, 0.16, and 0.04, respectively). Temp(cow) was explained by Temp(amb), clear sky insolation index, and cow albedo. However, ΔT was explained by Temp(amb), long-wave infrared radiation, Temp(cow), and cow albedo. Temp(cow) suggests red and black cows experience ~2× higher values than white cows at the coldest temperatures. ABSTRACT: Cattle in high-elevation rangelands experience cold and hot extremes. Given the increase in black hided cattle globally, thermoregulation options on rangelands, and hide color function affecting mammal thermal ecology, this study quantified winter albedo, external cattle temperatures (Temp(cow)), and differences (ΔT) between Temp(cow) and ambient air temperature (Temp(amb)), for different color cattle along a thermal gradient (≈−33 °C to +33 °C). From 2016 to 2018, I measured 638 individual Temp(cow) × Temp(amb) combinations for white (n = 183), red (n = 158), and black (n = 297) Bos taurus female cattle free roaming extensive Wyoming, USA rangelands. Pixel brightness of cow images relative to snow indicated mean (±standard error) albedo for white, red, and black cows (n = 3 of each) was 0.69 (±0.15), 0.16 (±0.04), and 0.04 (±0.01), respectively (p = 0.0027). Temp(cow) was explained by Temp(amb) (+), clear sky insolation index (+), and cow albedo (−). However, ΔT was explained by Temp(amb) (−), long-wave radiation (infrared; Rad(LW) (−)), Temp(cow) (+), and cow albedo (+). Temp(amb) relative to ΔT was correlated for all hide colors (all p-values < 0.0001; all r(2) values > 0.7)), yet slopes (m) were ~2× greater for red and black cows than white cows.