ive just seen the young eating and drinking yesterday and today.. seen and hear the parents vomit up water with whole seeds and/or pellets, when the young are less than about half feathered, so maybe they need to be told that they cannot and shouldnt do that, and havent had one die from it yet. unless rollers are differant than most in that way. if it doesnt eat and drink itll die anyway. im not trying to be punchy, just seen contrary, and maybe something else was a factor also. i havent hand fed too many baby pigeons though, just doves, finches, and mostly hookbills, temp.those babies at that age are not able to process water like an adult so when you give it to them it gives them the shoots an then they die