Coues' rice rats are small rodents that look like rats. They are usually 242 to 265 mm long, and weigh 42 to 83 g. They look a lot like marsh rice rats, but they are bigger and less gray. They are covered in brown fur on top. Their fur is lighter on their legs, faces, and sides. They have a layer of underfur on their backs that is soft, thick, and repels water. Males are a little bit bigger than females. Their skulls are light and thin. Their skulls are different from marsh rice rats because their upper molars have three rows of bumps instead of two. (Goldman, 1918; Vega, et al., 2007; Wolfe, 1982)
Coues’ rice rats live in the southeastern United States, and throughout Mexico and Central and South America. They also live on some nearby islands. Their spread across the United States is limited by the way water is managed for farming in southern Texas. (Alvarez-Castaneda, 1994; Merriam, 1901; Vega, et al., 2007)
Coues’ rice rats live mostly on land in grassy swamps or marshes along the coasts. They are good swimmers and divers who go underwater to escape, hunt, and find food. They may also live in high mountains nearby. (Benson and Gehlbach, 1979; Cook, et al., 2001; Goldman, 1918)
Coues' rice rats can reproduce any time during the year when there are good spots available to nest. This means their reproduction probably depends on their numbers and their environment. Females give birth to 2 to 7 young at a time, and usually around 4. They grow inside the bodies of their mothers for 21 to 28 days before they are born. If the conditions of the environment are right, females have 5 to 6 groups of young in the same year. Most of this happens between January and May. The young are born naked and blind, and weigh about 3 g each. They open their eyes on day 5 or 6 and drink milk from their mothers until around day 11. They are able to have their own young after 40 to 45 days. They reach their adult size of 48 g when they are about 9 months old. (Benson and Gehlbach, 1979; Cook, et al., 2001; Vega, et al., 2007; Wolfe, 1982)
The longest life of a Coues' rice rat was recorded to be 599 days. Males usually live about 165 days and females usually live about 167 days. (Clark, 1980)
Like other rice rats, Coues' rice rats are very active, social, and active at the night. They build nests from plants they find nearby in their marshy habitat. They are good at swimming and diving, and move their tails back and forth when they swim. This helps keep them balanced, and is good for finding food and getting away from predators. They can swim underwater farther than 10 m. They spend a lot of time cleaning and grooming themselves, which helps make sure their fur keeps repelling water. (Cook, et al., 2001; Wolfe, 1982)
Coues' rice rats probably communicate and get information about their environment in similar ways to other rice rats. This means they use their senses of sight, hearing, taste, and smell. They also use these same senses to communicate. When they are put into new environments in a laboratory, they use their noses and explore. (Wolfe, 1982)
Coues' rice rats are omnivores, so they eat both animals and plants. Some older scientific studies reported that they eat mostly seeds and parts of succulent plants, that they like grass stems in meadows, and that they eat meat as well. Later scientific studies reported that their diet changes depending on the season. These studies said that they eat about the same amount of plant and animal foods. The animal foods they eat most were insects and snails. They also eat fish, deer mice, and sparrows. Coues' rice rats store food to eat later. (Goldman, 1918; Wolfe, 1982)
A common predator of rice rats is boa constrictors, which affect the number of them in Central and South America. They are also an important food source for barn owls. Their close relatives, marsh rice rats, are most often eaten by owls. Rice rats are most often eaten by hawks, owls, cottonmouths and water snakes. Other predators include raccoons, red foxes, barred owls, minks, weasels, and skunks. (Vega, et al., 2007; Wolfe, 1982)
Coues' rice rats could spread human diseases. They get parasites like mites and ticks, fleas, and lice that could transfer to other animals or to humans. They have been infected with a kind of flukes from eating killifishes. They also have a kind of dental disease that scientists are researching. (Wolfe, 1982)
Coues' rice rats don't have any known positive impacts on humans. They don't interact much with humans because they usually are found in swampy and marshy areas where humans don't usually live. (Goldman, 1918)
Coues' rice rats are not endangered. They are most threatened by construction of roads taking over and disturbing their habitat. (Fuentes-Montemayor, et al., 2009)
Natalie Nguyen (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Catherine Kent (editor), Special Projects.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.
either directly causes, or indirectly transmits, a disease to a domestic animal
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
animals that generate their own body heat through metabolic processes.
parental care is carried out by females
union of egg and spermatozoan
marshes are wetland areas often dominated by grasses and reeds.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats all kinds of things, including plants and animals
having more than one female as a mate at one time
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
places a food item in a special place to be eaten later. Also called "hoarding"
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
Alvarez-Castaneda, S. 1994. Current status of the rice rat, Oryzomys couesi peninsularis. Southwestern Naturalist, 39(1): 99-100.
Benson, D., F. Gehlbach. 1979. Ecological and Taxonomic Notes on the Rice Rat (Oryzomys couesi) in Texas. Journal of Mammology, 60(1): 225-228.
Clark, D. 1980. Population Ecology of an Endemic Neotropical Island Rodent: Oryzomys bauri of Santa Fe Island, Galapagos, Ecuador. Journal of Animal Ecology, 49(1): 185-198.
Cook, W., R. Timm, D. Hyman. 2001. Swimming ability in three Costa Rican dry forest rodents. Revista de Biología Tropical, 49(3-4): 1177–1181.
Dewsbury, D. 1970. Copulatory Behavior of Rice Rats (Oryzomys palustris). Animal Behavior, 18: 266-275.
Fuentes-Montemayor, E., A. Cuarón, E. Vázquez-Domínguez, J. Benítez-Malvido, D. Valenzuela-Galván. 2009. Living on the edge: roads and edge effets on small mammal populations. The Journal of Animal Ecology, 78(4): 857-865.
Goldman, E. 1918. The rice rats of North America. Washington: North American Fauna.
Merriam, C. 1901. Synopsis of the rice rats (genus Oryzomys) of the United States and Mexico. Washington, D.C.: Washington Academy of Sciences.
Schnell, G., M. de Lourdes Romer-Almaraz, S. Martinez-Chapital, C. Sanchez-Hernandez, M. Kennedy. 2010. Habitat use and demographic characteristics of the west Mexican cotton rat (Sigmodon mascotensis). Mammalia, 74(4): 379-393.
Vazques-Domingues, E., R. Vega, A. Cuaron. 2007. Genetic Variability and Population Structure of an Island Endemic Rodent (Oryzomys couesi cozumelae): Conservation Implications. 2007 International Summit on Evolutionary Change in Human-altered Environments.
Vega, R., E. Vázquez-Domíngueza, A. Mejía-Puentea, A. Cuarón. 2007. Unexpected high levels of genetic variability and the population structure of an island endemic rodent (Oryzomys couesi cozumelae). Biological Conservation, 137(2): 210-222.
Wolfe, J. 1982. Oryzomys palustris. Mammalian Species, 176: 1-5.