The Bramble Cay melomys was known only from a small population in Bramble Cay, a vegetated coral cay of . The cay is in the eastern part of Torres Strait, off the northern tip of Australia. It is only 50 km from New Guinea. The melomys were probably trapped on the island by rising sea levels after the last ice age. It is also possible to have come from the Fly River, perhaps floating on branches. Scientists do not know much about the animals that live in the Fly River area.