Eye of the Monster — Andre Norton

Rees Naper had never trusted the reptillian Ishkurians, in spite of the fact that many of the Terran colonists thought they had been wronged. His worst fears were realized when the Terran authorities decided to grant the Ishkurians self-government and withdrew their protective forces from the planet.

It turned out that he was right--as soon as the last troops left the "crocs" went on a killing rampage.

Cut off from the remaining fortified outposts by miles of jungle and armies of crocs, Rees knew that his only chance for survival was to outwit the cunning rep-tiles. He had to learn to think like a croc, feel like a croc . . . and see through the eye of the monster!