My Ethiopian blessing cross (or hand cross) arrived in the mail recently (above, left; bottom), and more recently I found a matching processional cross (above, right). A gallery owner offered the following comments on the birds around the corner:
At the crucifixion, the birds (swallows) came to free Jesus from the thorns on his forehead. They carried away each thorn one by one to relieve the suffering.
In addition to birds, why do crosses have such an 'organic' motif, without the corpus? It turns out, the cross symbolically becomes the tree of life.1 In this re-framing, the Crucifixion itself overcomes the Man's sin in the garden--the first tree--but also opens us to the new life through the second tree, The Tree of Life. This harmonizes with St Athanasius' On the Incarnation: "that the Son of God himself became "fully human, so that we might become god.''