The young wallaby or joey, named Coral, is being handfed, The Detroit News reported. She spends most of her time in a fleece-lined sling designed to simulate the pouch marsupial mammals use for their young.
Coral's mother was among more than 27,000 exotic animals seized from a Texas dealer in 2009. About 1,000 of the animals were brought to Detroit.
Coral was found on the ground in July after her mother rejected her.
"She was the size of a cherry. She fit in the palm of your hand," said Bob Lessnau, the curator of mammals.
Coral gets round-the-clock care. Staff members take turns bringing her home at night.
Next year, she is expected to join the zoo's Australian Outback exhibit.
Wallabies resemble small kangaroos and grow up be about 40 pounds in weight with a height of 30 to 36 inches. Like other marsupials, female wallabies have a pouch that functions like an external womb. The newborn spends its first weeks in the pouch, sucking on its mother's nipples.