i think its used as a nest liner.. the squirrels here use grass, twigs, and all kinds of litter ( plastic bags etc) to build up their condo in the bird house, then I swear they line the monster with dog fur. I let big clumps of it blow, and its the soft under coat from my Sheppard, and they literally wait on the fence for us to leave the yard ( SMART) and then they scoot all over the place chasing the rare 'german tribble' around the yard, run up the fence and tree and gleefully pack it in.
The sparrows and other birds seem to weave it in thruout their nesting materials, incorporating it right into the nest itself. If I can I'll try and get some pictures inside the birdy/squirrel condo once the babes are bigger. Last year we had three of the little rats romping around... amusing as anything, so we'll see this year how many we have staying in the guest house.
