Don t overheat the water. Test it on yourself before you feed it to a baby bird. Crop Burn can be agonizing and can lead to death . It is a horrible way to go. Use a thermometer or just take the time to test the water before feeding and you shouldn t have to deal with this.
Aspiration can occur very easily.
This is the one most common cause of baby bird death caused by human handfeeders. Don t overfeed the bird. If the crop is semi-firm, it is firm enough. There is NO need to overstuff a baby bird. This can cause the food to expel into the throat, causing the bird to suffocate on its own food.