427.

Fulvous Pygmy Rice Rat

Oligoryzomys fulvescens

French: Colilargo fauve / German: Gelbbraune Zwergreisratte / Spanish: Rata arrocera pigmea leonada

Other common names: Fulvous Colilargo, Northern Pygmy Rice Rat

Taxonomy. Hesperomys fulvescens Saussure, 1860, “ Mexique.” Restricted by C. H. Merriam in 1901 to Orizaba, Veracruz, Mexico.

Six subspecies are recognized.

Subspecies and Distribution.

O. f. fulvescens Saussure, 1860 — E Mexico, most of Guatemala, S Belize, El Salvador, and Honduras.

O.f.engraciaeOsgood,1945—lowlandsofNEMexico.

O.f.lenisGoldman,1915—lowlandsofWMexico.

O.f.mayensisGoldman,1918—YucatanPeninsulaofMexico,NEGuatemala,andN&CBelize.

O.f.mnicaraguaeJ.A.Allen,1910—NWNicaragua.

O. f. pacificus Hooper, 1952 — Pacific coast of extreme SW Mexico.

Descriptive notes. Head—body 75-89 mm, tail 82-116 mm, ear 12-14 mm, hindfoot 19-24 mm; weight 10-17-5 g. Although some variation in size is evident (slightly larger individuals occur in the south of the distribution), the Fulvous Pygmy Rice Rat is the smallest of the Central American species of Oligoryzomys . Dorsum is pale tawny to reddish brown, flecked with bright buffy and dark hairs giving streaked or variegated appearance. Underparts are pale, whitish gray; over hairs may be entirely white to their bases, especially on throat and chest, or with light gray basal bands. Buffy overwash is present in some specimens; lateral ocherous stripe is prominent. Feet are covered with dense white hair; typical of the genus,tail is much longer (125-150%) than head—body length and slightly bicolor .

Habitat. Common in dry forests, generally associated with riparian zones, patches of succulents, or even tree ferns; old fields with herbaceous-woody plant combinations; but rare in mature forest with sparse understory from near sea level to elevations of c.1500 m. In general, the Fulvous Pygmy Rice Rat occurs in open grassy and weedy habitats, suggesting that they might be more abundant in disturbed habitats than in pristine forests.

Food and Feeding. The Fulvous Pygmy Rice Rat is mostly granivorous (up to 80% of stomach contents contained seeds) and insectivorous, but dietary preferences change seasonally up to 100% granivorous.

Breeding. Reproduction of the Fulvous Pygmy Rice Rat apparently occurs year-round because females with embryos were reported in January, July, and November; scrotal males were reported in July-August. Pregnant females carrying an average of four embryos (range 3-6) were found in Nicaragua.

Activity patterns. The Fulvous Pygmy Rice Rat is nocturnal and semi-arboreal; it uses understory vegetation while moving through its habitat.

Movements, Home range and Social organization. Juvenile Fulvous Pygmy Rice Rats are more numerous than adults, suggesting that longevity is less than one year. There is strong segregation between females that prefer mostly forested habitats (presumably for protection against aerial predators) and males that venture toward open spaces. Fulvous Pygmy Rice Rats sometimes make up 30% of rodent biomass in occupied habitats.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Alvarez et al. (1984), Baker & Villa (1954), Baltensperger & Brown (2015), Carleton & Musser(1995), Castro-Arellano & Lacher (2009), Dowler & Engstrom (1988), Engilis et al. (2012), Goldman (1918a), Hall (1981), Hall & Dalquest (1963), Hooper (1952c), Jones & Engstrom (1986), Kirkpatrick & Cartwright (1975), Landmann et al. (2008), McPherson (1985, 1986), Medellin (1994), Merriam (1901a), Nowak (1991), Osgood (1945a), Owen & Girén (2012), Pitts (1990), Reid (1997), Reid & Langtimm (1993), Ruan et al. (2008), Tan (2016), Timm (1994), Timm & LaVal (2000), Timm, Lieberman et al. (2009), Timm, Wilson et al. (1989), Villalobos-Chaves et al. (2016).