Birds are classified scientifically using a system devised by the Swedish naturalist Carl Linnaeus during the 18th Century. That system, titled Systema Naturae in Latin, has been adopted internationally. It undergoes constant revision as new species of plants and animals are encountered and previously known species require updating. This episode is an introduction to  classification of organisms scientifically as well as among Indigenous cultures in Arizona. Bird of the episode: Black-headed Grosbeak. Birding hotspot: Arboretum at Flagstaff. Friend of wildlife: American Conservation Experience.