I thought the tailfeathers were broken rather than dropped, although it's not really easy to tell one way or the other. It's very common for baby cockatiels to break their tails, especially if their wings are clipped. When the tail is dropped the feathers start growing back right away, but if they're broken they won't be replaced until the old feathers are molted out. So he might have a duck butt for a few more months.
I accidentally stepped on Squeebis's tail about a month ago and he dropped the whole thing. It's mostly grown back now, but he looked completely ridiculous for a while.
Here's what it looks like after a bird drops its tailfeathers. Look ma, no broken stubble!
