Guy, your shield looks like an old piece. I don't know about the chicken blood. I think it had a hard life.
Chicken blood is used on statues, that's true. But I never heard that tribes in the Congo worshipped their shields.
There are some good pics of this type of shield in the book : 'Shields - Africa, Southeast Asia and Oceania' from the Collection of the Barbier-Mueller Museum in Geneva. (pages 83 and 85).
There's also a basketry shield with the same narrow design from the same area as ours.
Anyway, here are some pics of my shield. Although faded, the colours are still there. Mostly blue, red and white.
My shield also has some engravings, like yours.
