Years ago, I had neglected to bring a house plant in for the winter. It was on a lower shelf, protected from the fall and winter rains, on an outdoor patio. Once I saw that I had lost the plant to cold temps I left the pot there intending to put another plant in it come spring. During the long winter days, when the ground was wet and cold, I watched many different birds sit in the pot of fine, dry soil and sing merrily as they used their feet to throw the dirt over their entire body. I was told that this helped them get rid of mites, dry their feathers and/or insulate them from the cold. I do not know why they do this but in the years since I have watched many little feathered friends sit in the dry soil and make fine music as they happily go about a taking a dirt bath.