Cliff-Hanger by Alane Ferguson, Gloria Skurzynski (1999, Hardcover)

The Landon family is off on another great adventure. Olivia Landon who is a wild life veteranarian has been invited to come to Mesa Verde National Park to examine a young couger who has supposedly has attacked some humans during the daylight. The day before the family is to leave they were asked to take on a foster child who was left at a roadside restaurant. Jack the oldest of the Landons' children was not enthusiastic about taking on a foster child before their trip but sister Ashley is always up to challenges. After a short period of time Ashley has a change of heart about Lucky, while brother Jack who is smitten by her wants to protect her. While Olivia examines the young couger, the rest of the family goes exploring at Balcony House or Cliff Palace. Their adventures/misadventures are always exciting making the reader feel like they too are right along with the Landons.