RAT, SILVER RICE

Oryzomys argentatus
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Muridae
Status: Endangered, ESA
Range: USA (Florida)

Rat, silver rice

Oryzomys argentatus (sometimes mistakenly called Oryzomys palustris natator)

Description and biology

The silver rice rat is a small rodent. It has a head and body length of 10 inches (25 centimeters) and a tail length of 5 inches (13 centimeters). The silver-gray color of the coarse fur on its back gives the animal its name.
The nocturnal (active at night) silver rice rat is a good swimmer. It feeds on seeds, insects, small crabs, and the succulent (sap-filled) parts of plants. Predators of the silver rice rat include foxes, skunks, snakes, and raccoons.
Biologists (people who study living organisms) know very little about the animal’s breeding behavior, but they believe a female silver rice rat gives birth to one to five young after a gestation (pregnancy) period of about 25 days.

Habitat and current distribution

Found throughout Florida, the silver rice rat is most endangered in the lower Florida Keys in Monroe County. It prefers to inhabit freshwater marshes, flooded mangrove swamps, and saltmarsh flats.

History and conservation measures

The silver rice rat faces the threat of habitat destruction as humans continue to develop areas in the Florida Keys. Much of its wetland habitat has been drained to create land suitable for homes and businesses.
Although the silver rice rat is preyed upon by a number of species, its most serious predator is the raccoon, which is native to the Florida Keys. As human development has increased on the islands, so has the amount of garbage. With an increased food source (the garbage), the raccoon population has grown unnaturally high. This has thrown the normal predator-prey relationship between the raccoon and the silver rice rat out of balance, and the number of silver rice rats has declined as a result.