Albedo and thermal ecology of white, red, and black cows (Bos taurus) in a cold rangeland environment

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 (Tempcow), and differences (∆T) between Tempcow and ambient air temperature (Tempamb), for different color cattle along a thermal gradient (≈−33◦C to +33◦C). From 2016 to 2018, I measured 638 individual Tempcow × Tempamb 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). Tempcow was explained by Tempamb (+), clear sky insolation index (+), and cow albedo (−). However, ∆T was explained by Tempamb (−), long-wave radiation (infrared; RadLW (−)), Tempcow (+), and cow albedo (+). Tempamb relative to ∆T was correlated for all hide colors (all p-values < 0.0001; all r2 values > 0.7)), yet slopes (m) were ~2× greater for red and black cows than white cows.