Mushrooms and apples are often seen resting in the branches of trees. Should you examine one, very likely you would find the marks of a rodent's teeth in its sides. This is one of the ways a red squirrel has of storing food. When he placed the mushrooms there, did he know that they would dry and be preserved? If so, why did not instinct tell him that the apples would decay before spring? October Twelfth Once the alarm note of a crow is heard and its meaning understood, you can always tell when those keen-eyed birds have discovered a hawk or an owl. "_Hak, hak, hak, hak, hak_," they call, much louder, quicker, and in a higher key than the regular "_caw, caw, caw_." Rarely do they strike a hawk or owl, but they keep diving at it until it soars beyond their reach, or takes shelter in a tree. Notes October Thirteenth If you can surprise a muskrat in a small pond, notice that he does not use his front feet (which are not webbed) in swimming; but, like the frog and the toad, holds them close against the sides of his body. Ordinarily the tail is used as a rudder, but when he is hard pressed, he whirls it round and round so that it acts like a screw propeller. October Fourteenth The brook trout is another fish that builds a nest. It makes a hollow in the bed of a brook or a spring, pushing the gravel aside with its nose, and carrying the stones in its mouth. By using its tail the cavity is shaped and then filled with pebbles, on which the eggs are laid, and covered with gravel. These "spawning" beds can now be seen in any spring-fed trout stream. October Fifteenth As soon as the foliage falls from the trees it is easy to collect birds' nests; and it is no sin to do so then, inasmuch as the birds mentioned this week rarely use the same nest a second season. Take a trip into the country with the sole object of hunting for nests, and you will be surprised to see how many you can find. One hundred and ninety-eight bird homes have been counted during a three hours' walk. When it is possible to take a part of the limb to which a nest is attached, it is best to do so. Notes October Sixteenth Besides the large pendent nest of the Baltimore and the orchard orioles, skilfully suspended from the end of an elm, maple, apple, or pear tree limb, you will find many smaller _hanging_ nests built by the several species of vireos. They are about the size of a tennis-ball; made of birch bark, paper, and pieces of dried leaves, fastened with spider and caterpillar webs, and they are lined with dried pine needles or dried grass. October Seventeenth The American goldfinch, "thistlebird" or "wild canary," usually places its nest in the angle of three twigs at the end of a slender branch that is nearly or quite perpendicular. The nest is larger than a base-ball, deeply hollowed and composed outwardly of pieces of cotton waste, plant fibres and fine bark, with a thick lining of willow or dandelion down, and other soft material. October Eighteenth