The correct answer to this open question is the following.
A coyote decided to take care of Bill because it found him lost in the area. The Coyote adopted him and treated him like other Coyote son. The story of "Pecos Bill" continues to describe that the coyotes "took good care of him." They fed him and taught everything he has to know to survive in the environment. That is why Bill was a healthy young man with many skills.