Avatar Kurruk was the last avatar before Kyoshi.  As he was born during an era of peace, he focused less on his duties as an Avatar, and focused more on the pleasures in life - wine, women & dice and the like.  Also developed a reputation as a hunter, and his most dangerous game being spirits.  However, the main reason he hunted those spirits was due to them growing restless due to neglect from his predecessor, Avatar Yangchen.  He never told the world about it because he didn't want to dirty Avatar Yangchen's legacy.