ecological competition, 173 eggs: buried, 55 covered, 46, 47 in other birds' nests, 91 specializations, 93 eider down, 71 environment modifies heredity, 139 Eskimo, credit to, 48 experience: crows profit by, 99 learning by, 189 feathers: and size of bird, 67 and temperature, 67 number of, 66 feeding rates of ani, 168 fish eats bird, 95 fishing with cormorants, 57 flavor of flesh, 63, 142 flesh: flavor of, 63, 142 poisonous, 141 fluctuations in the Arctic, 48 food: impaling of by shrike, 61 storage of, 32, 61 foster parents, 93 foster young, specialization in, 93 foxing, 166 frogs mistaken for birds, 109 gardens: animal, 183 ecological balance in, 153 of Arctic fox, 185 good and bad birds, 152 grackles, character of, 152 graveyards: 180 in hollow tree, 181 on island, 182 penguins', 180 green hunting jay, 164 guarding birds' nests, by insects, 121 guides to honey, 124 hair pulling, 102 helpers at nesting time, 81 heredity modified by environment, 139 hibernation, 108 honey guides: 124 lead to big game, 125 hornbills' nests, 42 households, mixed, 73 identification: caution in making, 161 errors in, 161 over the telephone, 160 sight, 161 incubation, artificial, 56 incubators, bird-made, 54 infantile behavior modified, 137 inquisitive birds, 210 instrumental music, 133 intelligence, comparative, 98 intoxication, 32 jays: change of color in, 164 helping at nest, 81 kingfisher: a painting of, 143 classical allusions to, 145 on the telephone, 143 variation in, 144 lammergeier and Aeschylus, 186 larder, shrike's, 60 laughing jackass, voice of, 145 learning, 189 lemming and Arctic fox, 49 lichens and birds, 184 listing of birds, early, 171 maladaptation, 31 megapode nesting, 54 migration, 28 mixed households, 73 monkey birds: 51 and birds, various, 52-53 mound builder and nest, 54 music, instrumental, 133 names: appropriateness, 51, 85 available scientific, 85 domestic and foreign, 157 euphony needed, 84 for boats, 84 how given, 51 natural selection not operating, 203 nests: co-operative, 79 decoration of, 207 Guarded by insects, 121 helpers at, 81 in soup, 38, 48 last year's, 69 leaves in, 207 megapodes, 54 parasitism, 91 secondhand, 69 subleases on, 69 transportation of, 28 use by man, 71 use of snakeskin in, 111 walled, of hornbill, 42--44 nest building, co-operative, 79 nidification, reptile type, 56 nursery, 35 oil glands, 25 owl, and toad, 190 owl, intelligence of, 98 oxpecker: 127 value to herds, 128