This is literally the second time feeding her with my fingers simulating her mother's beak. So simple, no need for elaborate contraptions. This mimics their natural feeding environment and is the ONLY way to get them to willingly open their beak so you can put food in it!
Trying to open the bird's beak does NOT work. The trick is simply closing your fingers gently around the bird's beak. When it feels your fingers wrapped around its beak, the bird will understand it's feeding time and open its beak immediately! Some people make devices to do this, but you can just do it with your fingers, and then with your other hand squirt the syringe of liquid food inside the beak!
After only a couple of feedings you will be able to do it with just 2 fingers; one on top and one underneath the beak. When the bird feels your fingers it will instantly know it's feeding time, open its beak, flap it's wings and start squeaking. When they're excited they'll hop around and make a mess of the feeding, but with a little practice you'll be a pro.
Enjoy and best of luck rearing your baby bird!
