Birds 13 Identification 12 Insects 7 Behavior 6 Trees 6 Butterflies 5 Ecology 5 more ... Fishes 5 Mammals 5 Freshwater fishes 4 Natural history 4 Classification 3 Geology 3 Paleontology 3 Wildlife conservation 3 Zoology 3 Aquatic insects 2 Bird watching 2 Botany 2 Caddisflies 2 Endangered species 2 Environmental aspects 2 Ferns 2 Freshwater invertebrates 2 Lichens 2 Mammalia (class) 2 Mammifères 2 Owls 2 Stream ecology 2 Waterfowl 2 less ...