Birds 653 Identification 121 Diseases 75 Cage birds 52 Behavior 46 Pictorial works 40 Birds of prey 32 daha fazla ... Bird watching 31 Bird populations 26 Ecology 25 Conservation 23 Migration 23 Nests 22 Bird Diseases 21 Congresses 20 Edible birds' nests 20 Geographical distribution 19 Birds, Protection of 18 Poultry 17 Ornithology 16 Anatomy 15 Avian medicine 14 Handbooks, manuals, etc 14 Mammals 14 Physiology 14 Case studies 13 Sea birds 13 Swifts 13 Avian influenza 12 Game and game-birds 12 daha az ...