Island mammal region A concept proposed by the biogeographer Charles H. Smith, which combines the Australian, Madagascan, and West Indian faunal subregions. The development of the characteristic mammalian faunas of these insular faunal regions is at least as much the result of their isolation by the sea as of ecological and geographic factors.

Island mammal region A concept, proposed by the biogeographer Charles H. Smith, that combines the Australian, Madagascan, and W. Indian faunal subregions. The development of the characteristic mammalian faunas of these insular faunal regions is due at least as much to their isolation by the sea as to ecological and geographic factors.