Sparrows.—Examination of many stomachs shows that in winter the tree sparrow feeds entirely upon seeds of weeds. Probably each bird consumes about one fourth of an ounce a day. Farther south the tree sparrow is replaced in winter by the white-throated sparrow, the white-crowned sparrow, the fox sparrow, the song sparrow, the field sparrow, and several others; so that all over the land a vast number of these seed eaters are at work during the colder months reducing next year’s crop of worse than useless plants.
Fig. 332.—African Ostrich, × ¹⁄₂₀. (order?)
Robin.—An examination of 500 stomachs shows that over 42 per cent of its food is animal matter, principally insects, while the remainder is made up largely of small fruits or berries. Vegetable food forms nearly 58 per cent of the stomach contents, over 47 per cent being wild fruits, and only a little more than 4 per cent being possibly cultivated varieties. Cultivated fruit amounting to about 25 per cent was found in the stomachs in June and July, but only a trifle in August. Wild fruit, on the contrary, is eaten in every month, and constitutes during half the year a staple food.
Questions.—Which of these birds are common in your neighbourhood? Which of them according to the foregoing report are plainly injurious? Clearly beneficial? Doubtful? Which are great destroyers of weed seeds? Wood-borers? Ants? Grain? Why is the destruction of an ant by a night hawk of greater benefit than the destruction of an ant by a woodpecker? Name the only woodpecker that injures trees. If a bird eats two ounces of grain and one ounce of insects, has it probably done more good or more evil?
CHAPTER XIV
MAMMALS
Suggestions.—A tame rabbit, a house cat, or a pet squirrel may be taken to the school and observed by the class. Domestic animals may be observed at home and on the street. A study of the teeth will give a key to the life of the animal, and the teacher should collect a few mammalian skulls as opportunities offer. The pupils should be required to identify them by means of the chart of skulls (p. [194]). If some enthusiastic students fond of anatomy should dissect small mammals, the specimens should be killed with chloroform, and the directions for dissection usual in laboratory works on this subject may be followed. There is a brief guide on page [223]. The following outline for the study of a live mammal will apply almost as well to the rabbit or the squirrel as to the cat.
The Cat.—The house cat (Felis domestica) is probably descended from the Nubian cat (Felis maniculata, Fig. [333]) found in Africa. The wild species is about half as large again as the domestic cat, grayish brown with darker stripes; the tail has dark rings. The lynx, or wild cat of America (Lynx rufus), is quite different. Compare the figures ([333], [335]) and state three obvious differences. To which American species is the house cat closer akin, the lynx (Fig. [335]) or the ocelot (Fig. [334])? The domestic cat is found among all nations of the world. What is concluded, as to its nearest relatives, from the fact that the Indians had no cats when America was discovered? It was considered sacred by the ancient Egyptians, and after death its body was embalmed.
The body of the cat is very flexible. It may be divided into five regions, head, neck, trunk, tail, and limbs. Its eyes have the same parts as the eyes of other mammals. Which part of its eye is most peculiar? (Fig. [333].) What part is lacking that is present in birds? How are the eyes especially adapted for seeing at night? Does the pupil in the light extend up or down or across the iris? Does it ever become round?
