Animals 118 Counting 100 Behavior 45 Dinosaurs 42 Birds 41 Natural history 36 Ecology 33 more ... Infancy 32 History 31 Paleontology 26 Science 25 Stories in rhyme 25 Experiments 24 Scientists 22 Butterflies 19 Insects 18 Picture books for children 18 Wildlife conservation 17 Picture books 16 Research 16 Animal behavior 15 Endangered species 15 Frogs 14 Zoology 14 Astronomy 13 Elephants 13 Mammals 13 Naturalists 13 Physicists 13 Plants 13 less ...