The streams and rivers that thread through Bwindi Impenetrable National Park are among the most productive wildlife habitats in the entire ecosystem — and among the most overlooked by gorilla trekkers whose attention is fixed on what happens in the forest canopy and on the trail ahead. The waterways that drain the highland catchment, running between mossy banks through the forest interior, support a community of mammals, birds, amphibians, and invertebrates that is distinct from and complementary to the more celebrated fauna of the forest itself.
The African clawless otter
The African clawless otter (Aonyx capensis) is the largest freshwater otter in the world, and it is present in the cleaner, faster-flowing streams of Bwindi’s interior. Despite its size — adults can reach over a metre in length and weigh up to fourteen kilograms — it is rarely seen by visitors because of its largely crepuscular and nocturnal activity patterns and its wariness of human presence. Tracks in stream bank mud, spraints (droppings) on prominent rocks, and occasional slides in clay banks near rivers are the most common evidence of otter presence for daytime visitors.
The African clawless otter is, despite its common name, not entirely clawless — it has vestigial claws on its hind feet, though the forefeet are fully unclawed and highly dexterous. This dexterity is central to its feeding ecology: unlike most otters, which use their mouth as the primary prey capture and manipulation tool, the clawless otter uses its nimble forepaws to feel under rocks and in crevices for crabs, molluscs, frogs, and fish. It can locate and extract prey in turbid or dark water entirely by touch, a capability that makes it an effective forager across a wide range of stream conditions.
Bwindi’s streams provide good clawless otter habitat: clear, cold, well-oxygenated water with a diverse invertebrate and amphibian fauna, rocky stream beds with abundant shelter sites, and forested banks that allow movement between sections without crossing open ground. The otter population in the park has not been systematically surveyed, but track evidence and occasional sightings by rangers suggest a stable if sparse distribution across the major stream systems of the interior.
Congo clawless otter: the rarer cousin
The Congo clawless otter (Aonyx congicus), a smaller and less studied species than its African relative, is also recorded in the Albertine Rift region and may occur in Bwindi’s higher-altitude streams. The two species overlap in range in this area and can be difficult to distinguish in the field, which has contributed to uncertainty in their respective ranges. The Congo clawless otter is classified as Near Threatened by the IUCN and is considered one of the less well-known of Africa’s carnivores, with population estimates based on very limited systematic survey data.
Side-striped jackals at forest edges
The side-striped jackal (Lupulella adusta) is the forest-edge canid of the Bwindi region, adapted to the woodland and cultivation mosaic that surrounds the park rather than to the closed forest interior. It is frequently heard at night from lodges positioned near the park boundary — the hollow, wavering howl carrying across hillsides in the hours after sunset. It is occasionally seen at dusk and dawn along forest edge roads and in the more open sections of the park boundary zone.
Unlike the more widely known black-backed and golden jackals of East Africa’s savannas, the side-striped jackal is a forest and woodland specialist with a diet weighted toward small mammals, insects, fruit, and carrion rather than the larger prey items that savanna jackals pursue. Its presence at Bwindi’s margins reflects the broader ecological transition zone that the park boundary represents — where the forest edge supports species from multiple habitat types simultaneously.
African golden cat: the forest’s most secretive large carnivore
Bwindi is one of the locations in East Africa where the African golden cat (Caracal aurata) is known to occur, though sightings are extraordinarily rare and most records come from camera trap deployments rather than direct observation. This medium-sized wild cat — roughly twice the size of a domestic cat, with variable colouration ranging from chestnut red to grey-brown and occasional melanistic individuals — is the only wild cat endemic to the African rainforest belt, and it is one of the least studied wild felids in the world.
Camera trap images from Bwindi captured in research projects run by the Wildlife Conservation Society and the Institute of Tropical Forest Conservation provide the primary evidence of the species’ presence in the park. The images show an animal that is primarily terrestrial but capable of climbing, that hunts duikers, rodents, and other small to medium prey, and that appears to be genuinely nocturnal — no camera trap images have been captured during daylight hours, explaining why the species is essentially never seen by visitors despite presumably being present throughout the forest interior.
Marsh mongoose in the wetland margins
The marsh mongoose (Atilax paludinosus) is Africa’s largest mongoose and is highly adapted to wetland and stream-bank environments. At Bwindi, it occurs along the permanent streams and in the Mubwindi Swamp — the permanently wet area in the park’s eastern section that is one of Bwindi’s most botanically and ecologically important habitats. Like the otter, it is largely nocturnal and rarely seen by daytime visitors, but its tracks — distinctive five-toed prints with prominent claw marks — are common in stream bank mud throughout the park.
The marsh mongoose feeds primarily on crabs, frogs, fish, and molluscs in aquatic habitats, supplemented by terrestrial prey when moving away from water. It is a strong swimmer and can dive for prey in clear streams, a behaviour observed in several Albertine Rift populations and documented by camera trap footage that has occasionally captured the species in action.
Watching for stream mammals on a gorilla trek
The most productive approach to encountering stream mammals in Bwindi is to slow down at every stream crossing during the approach hike and look carefully both upstream and downstream from the path. Otter tracks in wet sand or clay are often visible in the early morning when they are fresh from the night’s foraging activity. Spraints — dark, slightly musky-smelling deposits on prominent riverside rocks that otters use as territorial markers — are present year-round and indicate current otter use of the stream section.
The Buhoma sector, where the River Munyaga flows through the forest interior, is consistently one of the better areas for otter sign. The Ruhija sector’s streams, which run at higher altitude through more open forest, occasionally produce otter sightings in the early morning for visitors walking the road sections before the forest trail begins. If you have a specific interest in stream mammals rather than or in addition to gorillas, mentioning this to your guide before the trek allows them to route the approach through sections of the forest where recent otter activity has been noted.
