Maned Rat

The maned rat (Lophiomys imhausi), commonly called the African crested rat, belongs to the family Nesomyidae, subfamily Dendromurinae. It inhabits the moist montane forests, forest‑savanna mosaics, and rocky outcrops of the Albertine Rift, spanning eastern Democratic Republic of Congo, western Uganda, Rwanda, and north‑western Tanzania. Adults are among the largest African rodents, reaching up to 2.5 kg and a head‑body length of 45 cm. Their most striking feature is a dense crest of stiff, keratinized hairs that can be erected when threatened, exposing a bright orange‑red mantle that contains toxic secretions derived from the plant Acokanthera. The rat actively applies these secretions to its fur, creating a chemical defence that deters predators. The species is listed as Least Concern by the IUCN, but its fragmented distribution and dependence on specific forest habitats make it vulnerable to ongoing deforestation and agricultural expansion.

Maned rats are primarily nocturnal and solitary, establishing individual home ranges that may overlap marginally with those of neighboring conspecifics. Home‑range sizes average 0.5–1.2 km², with individuals defending core areas through scent marking and vocalizations. They are adept climbers, using their strong forelimbs to navigate tree trunks and rocky crevices. Communication relies on a repertoire of low‑frequency grunts, hisses, and tail‑slaps against the substrate, especially during territorial disputes or when a predator is detected. Though generally solitary, mother‑offspring bonds persist for up to three months after weaning, during which juveniles learn foraging techniques and the application of toxic secretions to their fur.

The maned rat is an opportunistic omnivore with a strong insectivorous component. Its diet comprises up to 60 % insects (beetles, termites, orthopterans), 25 % fruits and seeds (figs, berries, palm nuts), and 15 % tubers, roots, and occasional small vertebrates such as lizards. Foraging occurs on the forest floor and in low vegetation, where individuals use their sensitive whiskers and keen sense of smell to locate prey. They practice cache‑building, burying excess tubers for later consumption during dry periods. Seasonal shifts are pronounced: during the wet season, fruit intake rises, while in the dry season the reliance on insects and underground storage organs increases. The species also ingests the toxic bark of Acokanthera spp., which is later sequestered in specialized skin glands for defensive use.

Sexual maturity is reached at 10–12 months for both sexes. Breeding occurs year‑round but peaks during the rainy season (April–June), when food resources are abundant. After a gestation period of approximately 100 days, females give birth to litters of 1–3 well‑developed pups. Neonates are altricial, blind and hairless, and rely entirely on maternal milk for the first 4–5 weeks. The mother constructs a shallow nest of dry leaves and moss within a rock crevice or dense shrub. Pups are weaned at about 45 days and begin to explore the environment under maternal supervision. Juveniles acquire the ability to harvest and apply plant toxins to their fur by 8 weeks, a critical skill for adult defence. Sexual receptivity resumes in females after a 3‑month lactational amenorrhea.

The IUCN classifies the maned rat as Least Concern, yet the species faces several escalating threats. Habitat loss due to logging, mining, and conversion of forest to agriculture has reduced suitable range by an estimated 15 % over the past two decades. Fragmentation isolates populations, limiting gene flow and increasing vulnerability to stochastic events. Although not a primary target of hunting, incidental capture in snares set for larger mammals occurs in some regions. Climate change may alter the phenology of key food plants, potentially disrupting the seasonal availability of insects and fruits. Current population estimates suggest a total of 30,000–45,000 mature individuals, with a declining trend. Conservation actions include protecting remaining montane forest blocks, promoting community‑based forest management, and monitoring population dynamics through camera‑trap surveys.

• The maned rat is the only known mammal that deliberately applies plant‑derived toxins to its fur for defence.
• Its crest of stiff hairs can be erected like a porcupine’s quills, exposing the toxic mantle.
• It obtains the toxin primarily from the bark of the poisonous shrub Acokanthera schimperi.
• Despite its size, the species can squeeze through gaps as narrow as 5 cm, aiding escape from predators.
• Juvenile maned rats learn the toxin‑application technique by observing their mothers, a rare example of cultural transmission in rodents.