Southern Mexican states Veracruz and Oaxaca, through Central America and south to Northwest Colombia. It is usually found at medium to high elevations (up to 2400 m), but on the Caribbean coast in Costa Rica and Panama it has been found near sea level.

Biogeographic Regions: neotropical (Native )

Head and body length: 123-148 mm

Tail length: 133-196 mm

Hind foot length: 32-40 mm

Ear length: 16-20 mm

The forest spiny pocket mouse (Heteromys desmarestianus) is sexually dimorphic, with males typically weighing about one-third more than adult females. Size and weight also vary according to geographic location. They are smallest in East Panama and largest in the mountains of Costa Rica.

Heteromys desmarestianus has fur-lined, external pouches on either side of its mouth for temporarily storing and carrying food. The back, rump, and forearms are covered with stiff black-brown hair and peppered with interspersed cream-colored hairs. The sides are often paler black, and in dry lowlands some individuals may have a dusky-orange stripe on their sides. Ventral fur and feet are white. Their tail is bicolor with a black dorsal surface and a white ventral surface. The tail is sparsely haired, and usually about 20% longer than the head and body length, and may also have a white tip. Feet are long and narrow, and hind feet are naked. H. desmarestianus can be similar to other Heteromys species within some of its range, but can be differentiated by its dark forearms, hairless feet, and sparsely-haired tail.

Range mass: 46 to 87 g.

• Terrestrial

It is locally common in areas of wet rainforest, but it can also be found in areas of secondary growth or seasonally dry forest. In lowlands it is usually found in mature rainforest. H. desmarestianus favors habitat with abundant palms.

Terrestrial Biomes: forest ; rainforest

Although H. desmarestianus eats some insects and fruits, it is mainly a granivore. In Costa Rica, its diet consisted mainly of palm nuts (Socratea durissima, Euterpe macrospadix, Welfia georgii, Geonoma sp., and Iriartea gigantea), and other seeds (Meliosma sp., Pentaclethra macroloba, and Viriola sebifera).

Heteromys desmarestianus breeds year-round, but during extended dry periods some males and females may become reproductively inactive. Sexually active males have noticeably enlarged scrotal testes. Sexually active females can have up to five litters per year, with an average litter size of three and an interval between pregnancies of two months or longer. Annual survivorship probabilities are greater than 20%, and some individuals may survive up to 3 years in the wild.

H. desmarestianus has no special conservation status, but because it dwells in tropical forests it is negatively impacted by severe deforestation and non-forested agriculture. Currently it is still locally common in forested areas.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

No negative impacts have been reported or discussed.

Because it is such an avid seed hoarder, H. desmarestianus is probably an important disperser of palm seeds and other large-seeded species.