Stress lines? (2 Viewers)

[rkj]

Looking over old photos, I came across this one of a winter adult Ring-billed Gull which shows fine lines across many of the feathers. These are most visible on the back, but also can be seen on the flanks and breast. I am wondering if anyone can tell me anything about them. I know that feathers can develop stress lines during development as a result of variations in nutrition or other stress - is that what we are seeing here? This is not something I see on my other photos, certainly not to this extent. I am posting to the Ringing and Banding Forum because it seems to me those looking at this forum are most likely to be knowledgeable about such things; I would be happy to move it elsewhere if that seems better.