Native American Medicine Shield

As this attests, I collect all manner of things. Bought this twenty plus years ago at a flea market in New York City, of all places. Has a small paper tag on the back that reads "Plains Indian War Shield 1860 - 75". I have also seen these referred to as "hiding shields".

I have read that bird effigies were usually painted on the shield cover. On occasion, a mummified bird carcass was tied to the shield. This was done supposedly on "medicine shields". The medicine shield was also taken along in battle, but was meant to give spiritual protection. I believe this to be a medicine shield as it is approximately 16 inches in diameter and war shields are usually larger.

Looks to be rawhide stretched over a bent branch and tied as pictured. Feathers (eagle ?) and a small medicine bag are attached.

Paraphrasing from the book "The Mystic Warriors of the Plains" -

"As an eagle feathered head dress was the acme of all personal adornment, so the shield was the topmost summit of warlike paraphernalia. It occupied a conspicuous place in his lodge and was hung out on a fair day in front of the entrance. This shield is his protector and his medicine, almost a God."

Additional information would be appreciated.