I have a blue Swedish hen.Went out this morning to check on them and noticed feathers all over the run.She has lost or pulled her tail feathers out and those on her lower back.Its winter here. Why would she do this now? They have a heat lamp in the shed so she can stay warm if needed. The feathers were out in an enclosed area that we have protected from the snow and weather. Also have a heated pond for them to swim. I noticed she was shaking a bit while hissing .I am worried that she is bored or stressed because they don't go out in the winter. Do ducks molt in December ? The temps are cold here in Iowa.