Do Raptors React to Ultraviolet Light?

Birds are renowned for their excellent vision, including the sensitivity of many species to ultraviolet light (UV; Birkhead 2012). Bird color vision is mediated by four single-cone types, one of which houses SWS1 pigments that determine whether a species is sensitive to UV (<400 nm in wavelength) or only to longer wavelengths (reviewed by Hart 2001). Field observations led to the proposition that certain raptors might use the UV reflectance of vole urine to aid in hunting (Viitala et al. 1995, Koivula and Viitala 1999), although others have maintained that differences between UV reflectance of vole urine and underlying substrates were likely indistinguishable (Lind et al. 2013). Genetic studies by Odeen and Hastad (2003) suggested that raptors generally lacked UV-sensitivity, and most recently, sequencing of a Golden Eagle (Aquila chrysaetos) genome by Doyle et al. (2014) revealed genes indicating sensitivity to...