Marsh Rice Rat - Human Interactions

Human Interactions

The marsh rice rat is generally of little importance to humans, which is perhaps why it is not as well-studied as some other North American rodents. In 1931, Arthur Svihla noted that virtually no information had been published on the habits and life history of the marsh rice rat since the 1854 publication of Audubon and Bachman's description. Writing on Everglades mammals, Thomas E. Lodge notes that although the name "rat" may associate it unpleasantly with the introduced black and brown rats, its appearance is more endearing, even cute. J.S. Steward proposed the marsh rice rat as a model organism in 1951 to study certain infections that other rodents used at the time are not susceptible to. The marsh rice rat is quite susceptible to periodontitis and has been used as a model system for the study of that disease.

The marsh rice rat is the primary host of the Bayou virus (BAYV), the second most common agent of hantavirus infections in the United States. About 16% of animals are infected and the virus is most prevalent in old, heavy males. The virus may be transmitted among rice rats through bites inflicted during fights. It is also present in rice rat saliva and urine and human infections may occur because of contact with these excreta. Two related hantaviruses, Catacama virus and Playa de Oro virus, are known from Oryzomys couesi in Honduras and western Mexico, respectively. An arenavirus normally associated with woodrats (Neotoma) has also been found in Florida marsh rice rats. Antibodies against Borrelia burgdorferi, the bacterium that causes Lyme disease in the United States, have been found in marsh rice rats in Virginia, Maryland, North Carolina, and Tennessee. Another pathogenic bacterium, Bartonella, is known from Georgia marsh rice rats.

The 2009 IUCN Red List assesses the conservation status of the marsh rice rat as "Least Concern", because it is a common, widespread, and stable species without major threats that occurs in several protected areas. The Florida Keys form is rare and in decline and is threatened by competition with the black rat, predation by domestic cats, habitat loss, and loss of genetic variation; it is considered endangered. At the northern edge of its distribution, the marsh rice rat is listed as threatened in Illinois and whether it persists in Pennsylvania is unclear; it probably formerly occurred in tidal marshes on the Delaware River. In Illinois, its population may have regenerated because wetlands have been developed to protect waterfowl and shorebirds and because suitable wetlands often develop in abandoned coal-mining operations. A 2001 study projected that climate change would reduce the range of the marsh rice rat in Texas, where it is now common but may become threatened by habitat loss in the future. A study at the Paducah Gaseous Diffusion Plant found that rice rats accumulate more PCBs but less heavy metal than white-footed mice (Peromyscus leucopus).