13. What bird songs have you learned to know? When do these birds sing most? Does a bird have more than one song? 14. What birds have you seen near your home? What attached them to the vicinity? How might you attract more birds? Birds; Review and Library Exercise 1. What are the distinguishing characteristics of birds? 2. Give the orders of birds, with the characteristics of each order and an example of each. 3. Define and give illustrations of the meaning of the expressions: "land birds;" "water birds;" "shore birds;" "swamp birds;" "scavengers;" "policemen of the air." 4. Discuss the temperature of birds, the amount of energy they show, and the oxygen they use. 5. Beaks of birds. 6. Feet of birds. 7. The crop and gizzard. Why absent in many birds? 8. What is there in a bird's construction which enables it to twist its head so far around? What are the advantages in being able to do so? 9. Account for the oiliness of plumage of water birds; for the complete feathering of legs and feet in some forms. 10. Define moulting and discuss its advantages and disadvantages. 11. Give reasons why you would not expect a bird to hibernate. 12. Name two or more kinds of birds which show "recognition marks." What sort of birds would you expect to find with such marks? Why? 13. Is a bird's egg alive when it is laid? Why does it have so much food stored in it? What direct interest have we in this fact? 14. How are the eggs of various birds protected while they are developing? _Note._--Do not be satisfied with only one way. A bird seldom is. 15. Compare præcocial and altricial birds as to their stage of development when hatched; the location and character of the nest; the care given by the parents; the singing habit of the parents; the success of the type. 16. Name at least three insect-eating birds and tell how many insects it is estimated each will destroy in a day. Effect in a garden? 17. If you had an orchard to protect from insects would you spray it with poison, or would you police it with birds? _Note._--Consider both sides. There is much to be said on each. If you decided that you needed more birds, how would you get them? 18. Suppose you had a city lot in the suburbs, 50 feet wide by 200 feet deep, with a house covering the first 50 feet. Make a plan of the back yard to show what you could do to attract the birds to it in the summer; in the winter. Remember that birds must have protection against enemies as well as against changes in weather, etc. 19. For what purposes are birds killed by man? Which of these do you consider legitimate? Which birds may not legally be killed at any time of the year in this state? Which may at certain seasons? Which may at any time? When should an "open season" be permitted? How long should it last? 20. Give a short biography of Audubon. Describe the purpose of the Audubon Society and some of the work accomplished by it.