No mammal species are native on Diego Garcia, with no record of bats. Other than rats (''Rattus rattus''), all "wild" mammal species are feral descendants of domesticated species. During the plantation era, Diego Garcia was home to large herds of Sicilian donkeys (''Equus asinus''), dozens of horses (''Equus caballus''), hundreds of dogs (''Canis familiaris''), and house cats (''Felis catus''). In 1971, the BIOT Commissioner ordered the extermination of feral dogs following the departure of the last plantation workers, and the program continued through 1975, when the last feral dog was observed and shot. Donkeys, which numbered over 400 in 1972, were down to just 20 individuals in 2005. The last horse was observed in 1995, and by 2005, just two cats were thought to have survived an island-wide eradication program.