In the year, 2015, lethal heat waves and storms made it clear that humanity was changing the Earth. Anyone who paid attention to the news knew that Earth's animals and plants were disappearing. Total extinction of a species usually results after years of decline. In 2014, the World Wildlife Fund, the Zoological Society of London, and other organizations conducted an extensive analysis of more than 10,000 wildlife studies. The analysis produced a stunning conclusion: The total number of animals on Earth has declined by more than 50% since 1970. I have come to believe that nature conservation is the great challenge of our time. Human beings are imposing a mass extinction that will eliminate almost all animals on Earth. I believe that this Notebook will be useful for anyone wishing to accept the challenge and begin to work to protect Earth's creatures. This is how the Notebook came to be. In 2005, I decided I needed a checklist in which to record, in one place, all the wild animal species that I saw. After a long search, I discovered that the Arizona Game and Fish Department (AZGFD) maintains a statewide list of species. I used that list as a foundation, and supplemented it with lists from specialty organizations. Altogether, I was able to form statewide checklists for 11 species groups: amphibians, ants, birds, butterflies, dragonflies, fish, grasshoppers, lizards, mammals, snakes, and turtles. Though you will need several field guides to help with species identifications, you will need only this one book to keep a record of your species sightings. The AZGFD species list was created to show species conservation status-the health and stability of Arizona's plants and animals. I included conservation status in the checklists. Now, when you see an animal, you will have a place to record the sighting, and you will have expert opinions on that species' health and prospects for survival. The Arizona Wildlife Notebook is a useful too that anyone can use to add critical information to our knowledge of species distribution.