Rebecca Stefoff 
How Animals Think [PDF ebook] 

Birds that are smarter than a fifth grader–smart enough to do math, that is. Chimps that use tools. These are just two examples of the amazing skills of the animals all around us. In this jovial book, award-winning author Rebecca Stefoff tells us not just that animals are intelligent, but explains how researchers have discovered how smart they are. Readers will learn the languages of chimps and the mental maps of birds as well as the disputes that have arisen over the years about the very idea of animal intelligence.