This book was written with backyard birdwatchers like me in mind (although numerous species far beyond backyard birds are discussed). Dr. Kress presents a lot of interesting and varied information in a straightforward and conversational way, and there are great color illustrations on almost every page which provide examples to support the text. Although written in 1991 it did not feel outdated- especially as he includes a section on how climate change affects bird populations. It concludes with encouraging suggestions on how we can help birds survive and thrive.
A solid overview of pretty much every aspect of a bird's life, from plumage and behavior to flight mechanics and the way eggs are formed. I think the amount of detail provided is quite good given its short overall length and its target audience, and it didn't seem too out of date despite being published over 30 years ago.