From the publisher's website:
No matter where or when your campaign is set - from prehistoric times to the jungles of modern Africa - GURPS Bestiary provides all the creatures of fact and fantasy you need to bring your world to life. So come on - take a walk on the wild side!
Inside, you'll find:
Complete descriptions of more than 150 real and imaginary creatures, from Antelope to Water Buffalo, from Agropelter to Yeti.
Guidelines for using animals in your campaign, including detailed rules for hunting and trapping, venom, animals in combat, and animal companions.
Suggestions for inventing new creatures to keep players on their toes.
A complete set of habitat tables, showing where each species is most often found and giving their important stats at a glance.