Golden mouse
Encyclopedia
The Golden Mouse, Ochrotomys nuttalli, is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of New World mouse. It is usually 5–8 inches (12–25 cm) in body length, and has a golden-brownish color.

Habitat

Golden mice, O. nuttalli, live in thick woodlands, swampy areas, among vines, and within small trees and shrubs. These animals especially like to live where honeysuckle
Honeysuckle
Honeysuckles are arching shrubs or twining vines in the family Caprifoliaceae, native to the Northern Hemisphere. There are about 180 species of honeysuckle, 100 of which occur in China; Europe, India and North America have only about 20 native species each...

, greenbrier
Greenbrier
Greenbrier is the common name of the plant genus Smilax. It may also refer to:Places, United States*Greenbrier, Arkansas*Greenbrier, Orange County, Indiana*Greenbrier, Warrick County, Indiana*Greenbrier, Tennessee, in Robertson County...

, and red cedar
Juniperus virginiana
Juniperus virginiana is a species of juniper native to eastern North America, from southeastern Canada to the Gulf of Mexico, east of the Great Plains...

 grow. Golden mice in the south-central region of the United States inhabit climates that are hot and wet in the summer and dry in the winter.

Their nests may be located in the trees or on the ground. Ground nests, frequently located near leaf litter, may be fabricated within sunken areas of the soil or beneath logs. Ground nests have both advantages and disadvantages. Floods or wet soil may force golden mice to leave their ground nests and relocate into the trees. However, if the ground nest is undisturbed, it can lower the risk for predation for the following reasons: the nest is well hidden, a mouse on the ground is more likely to escape a predator, and less energy is required to build a nest on the ground since the mouse doesn't have to keep running up and down a tree with nesting materials.

Golden mice have been known to remodel old bird nest
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...

s into homes for themselves. Otherwise these animals create a nest 100 to 200 mm in size, from scratch using different elements, depending on what materials are locally available.

The inner lining of a nest consists of soft materials such as milkweed, cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....

, feathers, or fur. A thick layer of woven fibers surrounds this fluffy layer. The protective, surface material contains leaves, grass, and bark. The nest usually has one entrance, although up to fifty-seven have been noted.

Physical description

The body length of O. nuttalli ranges from 50 to 115 mm. The prehensile tail
Prehensile tail
A prehensile tail is the tail of an animal that has adapted to be able to grasp and/or hold objects. Fully prehensile tails can be used to hold and manipulate objects, and in particular to aid arboreal creatures in finding and eating food in the trees...

 is from 50 to 97 mm in length, generally the same length as the body of the mouse to which it belongs. Golden mice receive their common name from the thick and soft golden fur that covers the upper body. However, the feet and undersides are white and its tail have a cream coloring. Regional differences occur in the amount of yellowish, reddish and brownish overtones in the dorsal pelage. About five subspecies have been described, however, all are likely representative of a regional cline rather than distinct populations. Populations from the Atlantic coastal plain of Virginia, the Carolinas and Georgia (O. n. nuttalli) are somewhat brighter (more reddish yellow); populations from the Piedont and mountainous areas to the west (O. n. aureolis) are somewhat more brownish; populations from Texas, northern Louisiana, Arkansas, Missouri and Illinois (O. n. lisae and O. n. flammeus) have more yellowish overtones; populations from the Florida peninsula (O. n. floridanus) are rich yellowish-brown.

Male golden mice have a baculum
Baculum
The baculum is a bone found in the penis of most mammals. It is absent in humans, but present in other primates, such as the gorilla and chimpanzee.The bone aids in sexual intercourse.-Purpose:...

 tipped with cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

. Females have six mammae.

The cheek teeth of golden mice contain thick folds of enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...

. As in other members of Muroidea, these mice have an infraorbital foramen
Infraorbital foramen
Above the canine fossa is the infraorbital foramen, the end of the infraorbital canal; it transmits the infraorbital artery, vein, and infraorbital nerve.-External links: *...

 with a distinct keyhole shape. Neither canines nor premolars are present. Incisors are sharp and long, separated from the cheek teeth by a diastema.

Because of their attractive golden colour, golden mice have often been used in books, such a Ragweed, Poppy, Poppy and Rye, Ereth's Birthday and Poppy's Return. (see Edward Irving Wortis
Edward Irving Wortis
Edward Irving Wortis , better known by the pen name Avi, is an American author of young adult and children's literature. He is a winner of both the Newbery Honor and Newbery Medal.- Biography :...

)

Diet

Golden mice are granivorous, eating mostly seeds. They prefer sumac
Sumac
Sumac is any one of approximately 250 species of flowering plants in the genus Rhus and related genera, in the family Anacardiaceae. Sumacs grow in subtropical and temperate regions throughout the world, especially in Africa and North America....

 seeds, but also consume honeysuckle and other seeds as well. Sumac seeds are poor quality food because they contain tannin
Tannin
A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...

, which reduces the efficiency of enzymes in the mouse's digestive pathway. Studies have shown that females fed year-old seeds, which have more calories, have significantly higher mean ingestion and assimilation rates than females that eat freshly matured seeds.

Flooding is a problem for golden mice because the water causes the seeds to be unobtainable, to sprout, or to spoil.

Reproduction

Golden mice reproduce all year long. However, the reproductive season varies geographically. The majority of O. nuttalli reproduce from September to spring in Texas but from March to October in Kentucky and Tennessee. Golden mice in captivity tend to reproduce most frequently during the early spring and late summer. Because the gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...

 is only about 30 days, females can produce many litters in one year. Captive mothers have been known to produce up to seventeen litters in an eighteen month period. A litter of golden mice typically consists of two or three young, but ranges from one to four. Aside from the mother, all other adults leave the nest when the litter is born.

Behavior

Ochrotomys nuttalli is mainly nocturnal and arboreal, although many live on the ground as well. Golden mice move quickly and easily. They are able to use their prehensile tails to balance while climbing trees and also to hang from branches.

Ochrotomys nuttalli is a gregarious creature. In fact, up to eight mice have been discovered sharing a nest at one time. Groups can consist of kin or unrelated individuals. The most common groups consist of mothers and their young. Many scientists speculate that living in groups conserves energy. This idea is supported by the observation that mice are found in groups more often in the winter when such grouping produces a clear cut thermoregulatory benefit.

Golden mice have a low basal metabolic rate and high conductance. When their areas become flooded, golden mice activity is significantly reduced.

Ochrotomys nuttalli in captivity has displayed submissive behavior.
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