Thoreau writes in his journal:
P.M.—To Ledum Swamp . . .
I see a song sparrow’s nest here in a little spruce just by the mouth of the ditch. It rests on the thick branches fifteen inches from the ground, firmly made of coarse sedge without, lined with finer, and then a little hair, small within,—a very thick, firm, and portable nest, an inverted cone;—four eggs . . .