Well, it's Bantam.....

[FussyHen]

Yesterday morning I let my six hens out of the coop. Late yesterday afteroon, I found seven.

Number Seven is a beautiful little hen in full plumage, a bright, rich russet head and body, with a black tail. Short and cobby, with an upright tail, white legs, regular comb.

Leghorn?

Sorry, no photo capability.

 

[Sunshine0235]

Leghorn have yellow legs rather than white, im thinking old english game bantam is a possiblity.

Japanese bantams and seramas both have yellow legs too.

 

[popsicle]

A yellow-legged hen that has been laying eggs for a few months may have white legs.

 

[Wyandottes7]

My first guess would be that she's an Old English Game or a mix of OEG. They have white skin, and tend to be the most commonly found "wild" chickens because they are hardy and can survive well without caretakers.

 

[FussyHen]

The gamebirds are waaay too long, front to back. This one is as short in that direction as a chicken can be. And her tail is the shortest upright type, and looks like someone just dipped her whole tail in black paint.

I went through Google Images for both game hens and bantams, and nothing was very close. So I'm assuming that she's just a very pretty little mix. I don't think I've ever seen a chicken that SHINY -- very healthy-looking feathers.

My Columbian Wyandottes are making faces at her and calling her the "runt", so she's been hanging with the Ancona ducks.

 

[BantamLover21]

A photo would help us identify your mystery hen.

 

[popsicle]

Maybe Japanese?

From Cackle Hatchery site: