No tailfeathers or ass-feathers on fledgling

[arnoldus]

I've got 2 babyfinches of 17 days old, one of them is missing his tail feathers and has sparse feathering around the back part of his belly.
I'm not entirely sure, but could have sworn he had tail feathers a few days ago. Could this be a disease, or plucking behaviour?
Is it a problem, what could I do to improve?

[G8love4finches]

It is most likely someone plucked his feathers....I have a Society baby with no tail feathers as well....Don't worry much they will grow back....If it is a disease, then he will show signs like fatigue, fluffing and not doing much more than sitting....If he looks like he is doing the same as the other, then chalk it up to plucking....The feathers will grow back soon....Do you have a picture?

[Sally]

What species of finch? Usually, when you see baby finches missing feathers, one or both of the parents are plucking them for fresh nesting material (often the male is the culprit). You could try removing one parent and see if the other parent will continue to feed. If you have a dividable cage, that is perfect, because you could put mom and kids on one side, daddy on the other. Love those dividable cages!