Wow, different methods! When I had Lady Gouldian Finches and few canaries, I always fed them eggshells and hard boiled eggs (mashed, of course!) in the morning. I never had to add the salt or vinegar in the water. I put the eggs in the saucepan with cool water and let it rise the temperature to full boiling. It takes about 13 minutes from the start to end. The eggshells always came off perfectly. Set time, let's say you want to start with 10 minutes, if it fails, increase to 11 minutes, if it fails, then 12 minutes... so on until you get the perfect hard boiled eggs.
