Simplify the following text for a Grade 9 native English-speaking person.
Original: Goodall watched a hunting group isolate a colobus monkey high in a tree , block all possible exits , then one chimpanzee climbed up and captured and killed the colobus .
Simplified: Goodall watched a hunting group isolate a colobus high in a tree , block all possible exits , then one chimpanzee climbed up and captured and killed the colobus .