Do birds have belly buttons?

Stages in chick embryo development

All mammals have navels or belly buttons where the umbilical cord distributes nutrients between a mother and her fetus. After birth, the umbilical cord is cut and a scar develops on the abdomen where the hole closes. Humans have very obvious buttons. Other mammals like my cats have teeny, tiny, little, bare patches.

Of course avians or birds hatch from eggs which are virtually self-contained life-support systems that only require warmth and oxygen to develop properly. Instead of an umbilical cord scar, birds have yolk sac scars at hatching. This is where the chick embryo is attached to the yolk sac.

But don’t look for any bird belly button rings. The scars usually heal and become virtually invisible.

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Photo credit:  http://msucares.com/poultry/reproductions/poultry_chicks_embryo.html