Tylomys watsoniWatson's climbing rat

Geographic Range

Panama and Costa Rica. Range limits have not yet been determined.


Dense forest, mainly broadleaf rainforests, at low elevations and near bodies of water or rocky ledges. This species is arboreal.

Physical Description

Head and Body length= 184-260mm Tail length= 223-290mm. As with other members of this genus, T. watsoni is large and has a long, thick, hairless tail with a white tip. They look like large species of the genus Rattus. The braincase is flattened and long. They have large, naked ears, a pointed snout, and long, black whiskers. The feet are broad and short with white toes and dark brown fur on top. Their body fur is long, soft, dense, and usually grayish brown above and pure white below. There is a great deal of color variation within populations. Older adults are usually paler in color.


Nothing is known about the reproduction of this species. Other species in this genus have a gestation period of 40 days and an average litter size of 2.3 young.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual


This species is nocturnal and solitary. They have been recorded to inhabit trees at heights of 10 meters. Despite their common name, they are often sighted in rock piles, logs, and other ground habitats.

Communication and Perception

Food Habits

Plant material including fruits, leaves, seeds, lichens, and bark.

Economic Importance for Humans: Negative

Could be vectors for disease and pests in fruit plantations.

Conservation Status

Very little is known about the populations of Tylomys watsoni, but they are considered uncommon. They could also be threatened by habitat destruction.

Other Comments

This species has been very poorly studied.


Eric J. Ellis (author), University of Michigan-Ann Arbor.



living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

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. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


Emmons, Louise H. 1990. Neotropical Rainforest Mammals. A Field Guide. The University of Chicago Press. Pg. 188.

Goodwin, George G. 1946. Mammals of Costa Rica. Bull. of the Am. Mus. of Nat. His. Vol. 87. Pg 399-400.

MacDonald, Dr. David. 1984. The Encyclopedia of Mammals. Equinox (Oxford), Ltd.

Nowak, Ronald M. 1991. Walker's Mammals of the World, 5th ed. The Johns Hopkins University Press. Pgs 646-647.

Wilson, Don E. and DeeAnn M. Reeder. 1993. Mammal Species of the World. A Taxonomic and Geographic Reference. 2nd. ed. The Smithsonian Institute. Pg. 751.