Saw-whet Owl Florescent Feathers
Northern Saw-whet Owl feathers contain porphyrin pigments that fluoresce, or glow, a bright pink/raspberry colour under ultraviolet (UV) or blacklight. Newer feathers glow brighter, while older feathers appear darker. These colour differences can be used by banding station researchers to determine the age of an owl.
Key details about Northern Saw-whet Owl feathers
UV Fluorescence: The pigment (porphyrin) glows under UV light. It is invisible to the human eye but is likely used by other birds to identify age.
Aging Technique: New, molted feathers glow brightly, while older feathers are duller. A hatch-year bird will show uniformly bright feathers, while older birds will have a mix of new and old.
Physical Appearance: Under normal light, feathers on the underparts are white with broad brown streaks, while the legs and feet are densely feathered, with colours ranging from white to buff.
Tail and Wings: The tail has white-tipped rectrices with 2 to 3 bars.
The underwings feature white spots forming 4 to 5 bars.
Molting Pattern: Asymmetrical molting can occur, which means some new flight feathers are brighter than others.
