pensioner birds

[COUNTRY CAPITAL]

How do you identify an old bird?
apart from the obvious like overgrown toenails or some feather wear and tear, can you really tell by looking?
i have a masked finch or two in a large colony that pre-date any of my record-keeping so they are at least 5 years old, just lately i have noticed that they struggle with flying a bit.sometimes they more or less flutter to the ground.i have been expecting to find them expired on the floor but so far they just get around at a reduced rate.
other than this they appear normal/fit birds.
any tips/experiences would be appreciated.

[Shark]

It is very hard to tell old birds besides the symptoms you mentioned.
here is a few more some finches when inexperienced at feeding young get nipped around the face and neck, particularly the neck. This often doesn't fully heal and scarring results. Feathers are missing and/or grow at odd angles around the crop. This is particularly noticeable on birds whose colour changes around the crop like Longtails and Parrot Finches. You don't know this bird is old but you can tell it has raised young and who sells successful parents in their prime.
Another method is check the leg ring, leg rings begin to fade after a few seasons of sun and water. So this could mean the bird is passed it's prime.

[spanna]

Scaling on the legs is a good indicator of an aged bird. Young birds will have nice smooth legs while older birds will have white, dry, scaly looking legs. This isn't always the case, and can take a bit of identifying before you get used to it. A good indicator of age that I have noticed is how flighty the birds are. Of course, it depends on the species, but older gouldians for example are likely to let me get quite close before they take off, and younger (but still mature) birds will fly for the hills as soon as I come close. Something a bit different