Frequently there are more works in silver than there are in gold for any artist. Silver is less expensive and financially more accessible to work with. From silver to gold you are sometimes able to see the progression of an artist if they choose to carve a similar design. They will have completed the silver version first before attempting it in gold. I can’t say this on all of Bill’s engraved pieces but I would say I believe he would often carve a work in silver first before attempting it in gold, especially when looking at his earlier works.
From Cheryl Shearar’s “Understanding Northwest Coast Art”:
Bear is one of the most prevalent figures in crest and shamanic art, as well as in myths. It is considered to be a close relation of human-kind, perhaps because of physical characteristics such as size, appearance, and expression, and behaviours such as standing on two hind legs, gathering plants and berries, fishing and nurturing young.