What kind of bird is this?

The cat drug in a baby bird this morning (in Kansas we say “drug” not “dragged.”) I grabbed the cat, made him let go, then went and got my husband to deal with the rest. He caught the baby and let it go. Then he came to me and said, “That’s not a bird! It’s a chicken!”
“A chicken??”
Rick said, “Yeah…it’s got some big ol’ long legs!”
“Wait…a chicken is a bird. But you said it’s not a bird. Is it a giraffe?”
“No!...You know what I mean!”
“But where would a chicken come from??” We live in town, in a residential community.
“I don’t know!” He said.
So then he went and recaptured it and we stuck it in a box…It’s definitely not a giraffe, but it sure has some big old long legs, and some big, huge dinosaur feet too, and we’re wondering what to feed it. And will he stay in our yard? And will the cat eat him? Can he sleep with us at night? Can we potty train him? Where did he come from? Above all, IS it a chicken?