Visible and ultraviolet reflectance characteristics of arctic homeotherms

Reflectance characteristics of the epidermal coverings (hair, feathers) of several white birds and mammals were examined in the visible and ultraviolet regions of the solar spectrum. Non-white phases of the same species, and other non-white animals were examined for comparison. As expected, non-white animals exhibited lower reflectance values than white animals in the visible spectrum. Most species examined demonstrated reduced reflectance in the ultraviolet, reaching minimum values between 290 and 310 nm. In white animals, significant differences were found in the reflectance of UV-A (320–400 nm) and UV-B (280–320 nm) radiation. This accounts for the apparent differences in ultraviolet reflectance among various arctic mammals detected previously with ultraviolet photography. Reflectance patterns in the visible and ultraviolet were not obviously correlated with phylogenetic relationship, nor with the gross structure of hair or feathers.