Fret Marks (or stress marks, stress bars, shock marks, hunger streaks, hunger traces, etc)
Feathers reflect a bird's nutrition and general condition. If a bird is starving or has an imbalanced diet when she is producing new feathers, these feathers can have deformities called stress marks or hunger traces appearing as a line across the feather. These are weak points of the feathers.

           Feather image Kestrel with stress marks on her feathers.
Photo courtesy of Marra Apgar.

           Feather image Kestrel with stress marks on her feathers.
Photo courtesy of Steve Huy. © J. Steven Huy 2006




All images and text Copyright © 2004 - 2016 - Lydia Ash