They are glued onto the shaft with a simple V-splice, the bone being the negative, the shaft the positive. The bones had taken some damage on the cartilage parts from the cooking, fissures and cracks. I soaked them in dyed skin glue to help it. The dye is ordinary watercolour, matching the color he had wished the bow to be painted in. Fresh bones would certainly fare better.
He has used them quite some, mostly hitting the grass, but also rocks and trees and cartboard boxes and whatever. None has broken so far, but I would not expect them to hold up as good on full weight arrows shot from strong bows. No way. Unless you only hit soft birdies, of course.
One shows some abbrasion from hitting the concrete floor repeatedly, you can see it in the pic. They're bound to break some day, for sure.