Ultraviolet reflectance of colored plastic leg bands

The bright coloration of plastic leg bands used in avian research has been shown to affect the social interactions of birds by augmenting the ornamentation that traditionally mediates intersexual mate choice and/or intrasexual competition for mates. With ultraviolet (UV) vision and plumage reflectance playing a role in the mating decisions of some species, it would seem important to examine the UV reflectance properties of colored bands, as these bands may be providing strong and meaningful UV color signals that are invisible to the human eye and are potentially unaccounted for in most avian behavioral studies. In this study, we used a fiber optic spectrometer and a UV/visible light source to collect spectral reflectance data for the commonly used types and colors of bands and showed that none exhibit peak reflectance values throughout the range of LV wavelengths that is visible to birds. Instead, UV reflectance of colored bands at these wavelengths is comparable to levels of background reflectance found elsewhere in the avian visible spectrum. Consequently, colored bands lack discrete UV color signals and can safely be used in studies of wild birds with a minimal risk of influencing intraspecific signaling that is based on ultraviolet ornamentation. However, caution must be exercised when using these bands under experimental conditions, as certain treatments (e.g., indoor lighting, one-way glass, sunscreens) may mask the background levels of UV reflectance that still contribute to the overall band color, effectively inducing a color change in the bands that could provide unnatural visual cues to the birds and unintentionally influence their social interactions.