Millie is a Welsummer. Millie is crippled with gout, so she mostly lounges on her cushions all day. Before she volunteered for nanny duty, she was out with the other chickens who loved to abuse her feathers by raking their beaks over her. The result is a sort of "teasing" of the feathers so they appear more like fur than feathers. It's probably why Millie was so eager for nanny duty.