Osgood’s Vietnamese Rat – Rattus osgoodi – Musser & Newcomb, 1985

Science name: Rattus osgoodi – Musser & Newcomb, 1985

Taxonomic:  Animalia>> Chordata>> Mammalia>> Rodentia >> Muridae >> osgoodi

Species status: Endemic ; IUCN status: LC (Least Concern)

Description:

Physical Characteristics:
Size and Weight: Rattus osgoodi is a relatively small rat species. It measures about 9-12 inches (23-30 cm) from nose to base of the tail, with a shoulder height of approximately 4-6 inches (10-15 cm). Adult individuals weigh between 3-6 ounces (85-170 grams), making it a lightweight species compared to some other rat species.

Body and Coat: This species has a slender body with smooth, dense fur that is typically dark brown or gray in color. The underbelly is usually lighter. Its fur provides insulation in its montane environment. The tail of Rattus osgoodi is long and hairless, measuring 6-8 inches (15-20 cm), and is covered in scales, helping the rat maintain balance while moving through its environment.

Head and Face: The head is small and rounded, featuring a pointed snout and prominent whiskers. The rat’s eyes are relatively large and well-adapted for nocturnal activity, allowing it to see in low-light conditions. Its ears are proportionate to its head size and are covered in short fur. Like other rodents, Rattus osgoodi has sharp, continuously growing incisors for gnawing.

Distribution and habitat:

Altitude:
Rattus osgoodi is found at elevations ranging from 900 to 2,000 meters above sea level. Its preferred habitat is located in montane regions, where it can find suitable cover and food resources.

Range:
This species is native to Vietnam, specifically recorded in Lam Dong province. It has been observed in two localities, Langbian Peak and Gougah. The species is relatively localized to this part of southern Vietnam and has not been confirmed in other regions.

Habitat:
Rattus osgoodi inhabits a variety of montane habitats, including primary and secondary forests, grasslands, shrublands, and artificial environments such as plantations. It is particularly associated with dense shrubbery and grass near forest edges or scattered within open-canopy forests. This rat can also thrive in scrublands adjacent to agricultural fields, where it finds ample shelter and food resources.

Behaviour and ecology:

Social Structure:
Rattus osgoodi is primarily solitary but may live in small groups when food is abundant. It is mostly active at night, relying on its nocturnal vision and heightened senses to forage for food. During the day, it takes shelter in dense shrubbery, tree hollows, or burrows.

Feeding Habits:
This rat species is omnivorous, feeding on a wide variety of food sources. Its diet includes plant material such as leaves, fruits, seeds, and flowers, as well as small insects. Its opportunistic feeding behavior allows it to adapt to changes in its environment, especially in areas affected by human activity. The species is known to be particularly fond of fruits like figs, which make up a significant portion of its diet.

Reproduction:
The reproductive habits of Rattus osgoodi are similar to those of other rats. Females have a gestation period of around 21-24 days and give birth to litters of 4-8 young. The newborns are blind and hairless, relying on their mother for warmth and nutrition. The pups are weaned at around 3 weeks of age, at which point they begin to explore their surroundings. Sexual maturity is reached by 8-10 weeks of age, after which the young are ready to reproduce and establish their own territories.

Conservation and status:

IUCN Red List Category and Criteria:
Rattus osgoodi is listed as Least Concern on the IUCN Red List. It has a stable population and occupies a range of montane habitats in southern Vietnam. There are no major known threats to its population.

Population Trend:
The population of Rattus osgoodi is considered stable. It does not exhibit severe fragmentation, and there is no evidence of a significant decline in mature individuals.

Threats:
Although there are no immediate threats to Rattus osgoodi, potential risks include habitat loss due to deforestation and agricultural expansion. However, the species’ adaptability to secondary habitats and human-altered environments helps mitigate these risks.

Conservation Actions:
There are currently no specific conservation measures in place for Rattus osgoodi, but its presence in various habitats, including protected areas, ensures some level of security. Continued monitoring of its population and habitat quality is essential for long-term conservation.