Why did I trap these baby birds inside their mother?

Why did I trap these baby birds inside their mother? I'm finally telling the story of my viral chicken maraca. So, I started with a clay hen, sliced her and scooped out her insides, and this was actually my first time making a hen this way. Usually, I use the pinch pot technique, and having two halves gave me the idea to add some clay inside to make a maraca. As I formed balls of clay with the scooped out parts, I thought, birdies would be so much cuter. So, I made two little birdies, each with their little personalities. We named this one Cookie because she's round like a cookie, and the taller one Chippy like chocolate chips. They may not look like chicks, but the head feathers were too cute, so I had to put them on. I put them inside their mama hen and got one last look at them before I sealed her up, hoping that after firing, they wouldn't stick to the inside and never make a noise. I didn't want them to be forgotten forever, so after painting black underglaze on the hen, I carved the babies onto the mama hen with the sgraffito technique, along with a little field of flowers for them to frolic around in. I was so, so, so nervous when I glaze fired the hen, because although the babies did shake around after a bisque fire, they could still stick after the final fire. Here's what happened when I opened the kiln. There she is! Oof, very hot. Look at the babies! Aaah! The babies stuck! So sad! The babies are welded inside... for all eternity... Ok, actually a few hours later it worked! When I tried shaking the maraca hen right out of the kiln, the clay was still very hot and probably slightly expanded, squishing the babies a bit, maybe, until it cooled down and loosened them up, so they could perform their maraca duties. Now I'm working on a bigger maraca hen, this time with six babies!