Kemps grass mouse

Deltamys kempi

TAXONOMY

Deltamys kempi Thomas, 1917, Isla Ella, Delta of the Parana River, Argentina. Tribe Akodontini.

OTHER COMMON NAMES Spanish: Ratón aterciopelado.

PHYSICAL CHARACTERISTICS

Measurements of the holotype. Total length 6.9 in (174 mm), tail length 3.3 in (85 mm), ear length 0.5 in (13 mm), length of foot without claws 0.9 in (22 mm). Eyes are small and barely visible, ears are narrow. The soft pelage is blackish brown dorsally and dull brownish gray ventrally. Tail is faintly bicolored.

DISTRIBUTION

Small area of southeastern South America, from northeast Buenos Aires Province and southern Entre Ríos Province in Argentina, throughout south, central east, and northeast Uruguay, to the Atlantic coast of the Rio Grande do Sul State in Brazil.

HABITAT

Marshy areas, especially edges of wetlands, flooded grasslands, and places with reeds and straws. In Uruguay also inhabits, although less abundantly, some woodlands. In

Argentina it has also been collected in tall grass coastal areas and gallery forest.

BEHAVIOR

Probably fossorial. It rests under grasses and leaves. FEEDING ECOLOGY AND DIET

Mostly carnivorous. Insect remains have been recorded in stomachs of Argentinean and Uruguayan specimens. In addition, seeds and remains of green plants have been found in stomachs of specimens collected in Uruguay.

REPRODUCTIVE BIOLOGY

Little is known on reproductive aspects of Kemp's grass mouse. Litter size may be three since that numbers of young were found in one nest in Argentina and another in Uruguay.

CONSERVATION STATUS

In Argentina it is considered rare and at lower risk. Uruguayan populations are considered not threatened. The status of Brazilian populations is not known.

SIGNIFICANCE TO HUMANS None known. ♦

OTHER COMMON NAMES Spanish: Rata arrocera, coludo.

PHYSICAL CHARACTERISTICS

Total length 8.9-12.0 in (225-305 mm), tail length 3.9-6.9 in (100-175 mm), hindfoot length 1.1-1.5 in (28-37 mm). Weight 1.4-3.0 oz (40-85 g). Generalized rat-like appearance. Dorsal coloration range varies from grayish brown to gray. The venter is much lighter. The underfur is water repellent. Eight pairs of mammary glands. The forefoot and hindfoot have four and five toes, respectively. Tail is scaly, long, and nearly naked.

DISTRIBUTION

Endemic to the United States, ranging from southeastern Pennsylvania and southern New Jersey to the tip of Florida and westwards to eastern Texas. There are records from southern Kentucky and Illinois, southwestern Missouri, and southeastern Oklahoma.

HABITAT

Common in wetlands, including marshes at the Atlantic and Gulf coasts. It also inhabits swamps, meadows, and prairies.

BEHAVIOR

Semiaquatic, being good swimmers and divesr. Primarily nocturnal. High-pitched squeaks were associated with agonistic behavior upon females by males in captivity. It constructs spherical grassy nests to sleep in during the day.

FEEDING ECOLOGY AND DIET

Carnivorous, but also feeds on seeds, succulent plant parts, and fungus. Food items may vary seasonally upon resource avail-

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