Interesting news indeed Jonathan . . .
Length of time in captivity may not be the only factor in the extent of cage damage. While certain aspects (e.g. bumble foot and aberrant moult) are related to the time in captivity. Trapped birds, especially if roughly extracted, could show plumage damage from the moment of capture.
Other factors likely to affect the amount of cage damage could include the size and design of the cage relative to the size of the bird, how hard the bird tries to escape, the degree of stress, the amount of crowding in the cage, possibility of aggression by other birds and the presence or absence of feathers especially prone to damage (e.g. the tail of a White-rumped Shama).
Cheers
Mike
Mike KilburnVice Chairman, HKBWSChairman, Conservation Committee