Part 1: Introduction to squirrels of the world and their conservation trends. Chapter 1: The World's Squirrel Taxonomy -- Chapter 2: Evolution, habitat trends, and extinction rate estimates of the world squirrels -- Part 2: Squirrels of the world in the Anthropocene. Chapter 3: Habitat Trends and the Squirrel-Human Interface -- Chapter 4: A Meta-analysis based on Open Access Big Data Mining of Global Predicted Squirrel Distribution Models with Machine Learning for IUCN Conservation Status and Trend Policy Assessments -- Chapter 5: Squirrels in Cities -- Chapter : Squirrels in the Tropics -- Chapter 7: Squirrels on Islands -- Chapter 8: Tree squirrels in old-growth forests? -- Chapter 9: Can squirrels be used as indicators to identify and protect old-growth forest reserves? -- Chapter 10: Squirrel Economics -- Part 3: Problems and governance in the squirrel world. Chapter 11: Squirrel Hunting Regulations and Enforcement (Or Lack Thereof) -- Chapter12: Where do the World's Squirrel Hotspots and Coldspots of 230+ species go with Climate change 2100? -- Chapter 13: Squirrel's marginalization and modern lack of conservation and poor sustainability outlook as a call to good action -- Part 4: First conclusions and the way forward. Chapter 14: A Conservation Management SWOT analysis for over 300 Squirrels of the World using 132 GIS layers confirming the PESTLE assessment -- Chapter 15: First Conclusions, Success stories, and Calls-to-action for the conservation of the world's squirrels.