In 1914 Curwood published the novel Kazan. A story about a tame wolf-dog hybrid and written from the viewpoint of the dog, Kazan travels to the Canadian wilderness, is separated from his master and lives with a pack of wolves. Kazan sold over 500,000 copies and is often compared to Curwood's contemporary Jack London's White Fang, which was published in 1906. Curwood's story became a major motion picture in 1949 by Columbia Pictures (IMDB). 

Curwood’s success as a writer did not happen overnight. He wrote for ten years before he sold his first story, and twenty-five years before he made a comfortable living at it. His advice to authors was the same that he took for himself, “hard and steady work for years, with a fixed purpose.” 

In the same year, while Curwood was on a hunting trip in the Rockies, he saw a large bear he called Thor.  He tried to shoot him three times in three weeks.  One day as Thor approached him, he slipped and fell, breaking his gun.  The bear reared up to attack but walked away leaving Curwood untouched. The experience dramatically shaped Curwood's perspective of hunting for trophies to becoming an advocate for preserving nature. In 1916 he wrote a story from his experience called The Grizzly King which became a major motion picture called The Bear, released by RCA Columbia Pictures in 1990 (IMDB).