I've heard that its safe to feed them: kiwi, pears, bananas, apples, pineapples, grapes, oranges, peaches, tangerines, melons, strawberries, figs, cherries, raspberries, apricots, and blackberries.
As long as they're washed good, but I know you already know that!
And about Star being skinny.... I think its normal. Norri seems sorta-skinny, and I know he eats plenty. I'm not certain about your budgie, though!
Hope I was helpful in some way.