His main research field are the endemic avifaunas of Hawaii and other islands in the Pacific where he was one of the pioneers of the voice recordings of birds.
With his dissertation A systematic analysis of the endemic Avifauna of the Hawaiian Islands he promoted to PhD at the Louisiana State University in 1979.
Before he became curator of birds at the North Carolina State Museum of Natural Sciences in Raleigh he worked as research associate at the Louisiana State University in Baton Rouge from 1980 to 2005.
[4] Pratt wrote important revisions within the genus Zosterops[5] and the subfamily Drepanidinae.
Pratt has illustrated at least 20 books, including several plates in the Handbook of the Birds of the World and he created several bird and mammal paintings in the Encyclopædia Britannica, despite having no formal art training.