Use of ultraviolet light to help age nightjars, owlet-nightjars, frogmouths and owls
Australian Bird Study Association Inc
Place of Publication
School of Science
Ultraviolet (UV) light is widely used by researchers to help determine feather generations of most North American owls. It was originally developed for use on Barn Owls Tyto alba; however, it is most extensively used on Northern Saw-whet Owls Aegolius acadicus due to the frequency at which this species is banded (Weidensaul 2011). Its use is possible because exposing feathers that contain porphyrin pigments to UV light results in them fluorescing a spectacular, hot pink colour (Gill 2007). The pigments degrade over time as feathers are exposed to sunlight, resulting in older feathers fluorescing less brightly than newly grown feathers (Gill 2007; Weidensaul 2011). Moult stages are identifiable under incandescent light by looking at the amount of wear and fading of the feathers, although this requires significant experience on the part of the bander. The use of UV light enables inexperienced banders to easily and accurately identify moult patterns. Although moult strategies differ between species, some are predictable. Therefore, by understanding moult patterns researchers are able to accurately age these kinds of birds (Rogers et al. 1986).