Contents. 



PAOE 



Introductory. — The Utility of Birds in Nature, .... 1 



Chapter I. — The Value of Birds to Man, .23 



Primitive Man's Relations to Nature, ....... 23 



Changed Relations produced by Agriculture, ...... 24 



Man at War with Nature in the New World, 25 



The Increase of Insect Pests, ......... 27 



The Number of Insects, 28 



The Reproductive Capacity of Insects, . 28 



The Voracity of Insects, . 30 



The Great Loss to American Agriculture by Insect Ravages, . . .31 



Losses by Insect Ravages in Massachusetts, 36 



The Capacity of Birds for destroying Pests, ...... 40 



The Digestion of Birds, 40 



The Growth of Young Birds 42 



The Amount of Food required by Young Birds, . . . .44 



The Time required for Assimilation of Food, ..... 49 



The Number of Insects eaten by Young Birds in the Nest, . . 51 



The Amount of Food eaten by Adult Birds, 57 



Birds save Trees and Crops from Destruction, ..... 63 



The Increase of Injurious Insects following the Destruction of Birds, . 72 



The Destruction of Injurious Mammals by Birds, ..... 76 



The Value of Water-birds and Shore Birds, 80 



The Commercial Value of Birds, ........ 81 



The .Esthetic, Sentimental, and Educational Value of Birds, . . 85 



Chapter II. — The Utility of Birds in Woodlands, .... 90 



The Relations of the Bird to the Tree, 91 



The Forest Planters 92 



The Influence exerted by Birds and Squirrels on the Succession of 



Forest Trees, 96 



The Tree Pruners 99 



The Guardians of the Trees, ......... 100 



Chapter III. — Birds as Destroyers of Hairy Caterpillars and 



Plant Lice, Ill 



Chapter IV. — The Economic Service of Birds in the Orchard, . 149 



Chapter V. — Song Birds of Orchard and Woodland, . . . 155 



Woodland Thrushes, 155 



Kinglets, 160 



Nuthatches and Tits, 163 



