1937- 1960- 1960-1980 adams agriculturalecology alpaca animalproducts autobiography bibliography bigcats biography canada canadianhistory cats children'sfiction collegesuccess colorado congres congresses denverartmuseum droughts ecology ecosystems ecotourism endangered english environmentalconservation environmentalists essays fiction friendship frontierandpioneerlife gardening general generalinterests grasslandpeople grasslands greatplains habitats history hobbies household humangeography jeffreyalan juvenilefiction juvenileliterature juvenilenon-fiction landscapephotography leopards lions literary lockwood madrastras mammals management moving naturalists nature northamerica novelajuvenil pictorialworks plains prairieanimals prairieecology prairieplants prairierestoration produitsanimaux protection ranchlife robert seasons sequías socialsciences soilconservation spanishlanguagematerials spirituality stepfamily stepmothers stepparents survival tigers travelogues unitedstates vidafronterizaypionera weather wildlife wildlifereintroduction wittingfamily(fictitiouscharacters) zoos