Harper and several other researchers have attempted to prove the former existence of a king vulture relative in Florida at this late date, suggesting that the population was in the process of extinction and finally disappeared during a cold spell.
Beberapa peneliti telah berusaha membuktikan bekas keberadaan kerabat Hering Raja sebelumnya di Florida, mengusulkan bahwa populasi burung tersebut berada pada proses kepunahan dan akhirnya menghilang dari Florida selama masa dingin .