Yikes - time got away from me! In Downy and Hairy Woodpeckers, both the males and females brood chicks and help incubate eggs. To prepare for this activity, both hormones and the birds themselves loosen and remove feathers on their abdomens. This allows for the skin to be in direct contact with eggs, to maximize the amount of body heat tranference. The veins enlarge, allowing for even more heat to warm the eggs. When the eggs hatch, the veins start to recede. However, the skin is still stretched out. You can see from these pictures that the skin is still wrinkly, meaning we know the bird's eggs have hatched and there are now young in its cavity nest!