The Cape clawless otter according to MammalMAP
Cape clawless otters are the second largest freshwater species of otter. Their name is derived from their characteristic partly webbed, clawless feet.
Quite the robust animal, cape clawless otters are predominantly brown with a white underbelly. Their elongated, agile bodies are well adapted for swimming. Its coat consists of densely packed underfur and long guard hairs that traps a pocket of insulated air underwater.
This mammal can be found in aquatic habitats – usually residing near perennial springs and rivers. Cape clawless otter prefer shallow water with thick reed beds full of their favourite crab and fish snacks. They will also feed on molluscs, birds, rodents and amphibians. They are no strangers to estuaries and the beach either – as long as there’s freshwater for drinking nearby.
Female otters may breed at any time of year and typically give birth to a litter of 1 -3 pups in a sheltered den. Females are devoted mothers and will teach the pups how to find and secure prey. Family groups are usually spotted during peak activity periods – usually early morning or late afternoon.
The IUCN classifies Cape clawless otters (Aonyx capensis) as a species of Least Concern. The species is widespread and most populations are thought to be stable.
Aonyx capensis is the most widely distributed otter species in Africa. Their home range is limited to the African continent, stretching along the coast from South Africa to Ethiopia and across the continent to Senegal. Unlike their close relative Aonyx capensis congica, Aonyx capensis does not occur in the central African rainforest region of the Congo basin. Aonyx capensis and A. capensis congica are sympatric in Uganda and Rwanda.
Biogeographic Regions: ethiopian (Native )
African clawless otters are the largest Old World otter species and 3rd largest species of otter overall. Their head and body length ranges from 762 mm to 880 mm. Their tail measures 465 mm to 515 mm long and is typically stout and tapered. They weigh between 10 and 22 kg. Males are slightly heavier and longer than females. Their thick shiny coats are colored dark brown except for distinctive white coloring on the upper lips, the sides of the face, neck, throat, belly, and lower ears. Otter pelage consists of two kinds of hair. The outer hairs, or guard hairs, measure up to 25 mm in length. The undercoat, or fur, is white to off-white and is made of short (10 mm), fine, wavy hair. African clawless otters have long white whiskers on their cheeks, chin, and brows, which are used to detect prey in murky waters. They are clawless except for small grooming claws on hind digits 2, 3, and 4. Although their hind feet are partially webbed, they have the least amount of webbing of all otter species. They have nimble forefeet with opposable thumbs. Rough skin lines their palms and fingers and helps to grip slippery prey. African clawless otters have large skulls, measuring 125 to 136 mm in length. They have a broad, flattened brain case and a small sagittal crest. Brain size is large compared to skull size, the rostrum is short and broad, and zygomatic arches are slender. African clawless otters have large molars, specialized for crushing crustaceans and fish skulls, and no cutting teeth. The shape of their molars varies geographically. They possess a pair of anal scent glands are used for scent-marking. Males’ foreskin protrudes from their body but the penis resides beneath their thick skin. Females have two pairs of mammary glands on their abdomen.
Range mass: 10.6 to 21 kg.
Range length: 730 to 880 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
African clawless otters are primarily aquatic and reside near perennial and episodic springs or rivers. Marine populations do occur if a source of freshwater is nearby for drinking. These otters prefer shallow water with thick reed beds, which are home to several favorable prey such as crab and fish. On land, African clawless otters take shelter in underground burrows, under rocks, roots, or dense vegetation. Dens have been found from sea level to 1200 m in elevation. Dens are used for resting, playing, eating, defecating, and giving birth and are shared by multiple otters. African clawless otters have been known to dig burrows in the sand up to 3 m deep, with entrances to the den above and below the water surface. Burrows typically contain a nest made of grass or other vegetation. Dens are never farther than 50 m from shore or 15 m from freshwater. They are usually close to abundant food supplies and densely vegetated areas. African clawless otters do not typically dive farther than 1.5 m below the surface of the water.
Range elevation: 0 to 1200 m.
Average depth: 1.5 m.
Habitat Regions: tropical ; terrestrial ; saltwater or marine ; freshwater
Terrestrial Biomes: savanna or grassland ; forest ; rainforest
Aquatic Biomes: lakes and ponds; rivers and streams; temporary pools; coastal ; brackish water
Other Habitat Features: riparian ; estuarine
Habitat and Ecology
African clawless otters are primarily carnivores. In freshwater habitats, their diet consists primarily of crabs (Potamonautes); however, they also eat frogs (Xenopus), insects (Coprinae, Cyclorhapha, Dytiscidae, Nepidae, Odonota, Scarabaeidae), and various species of fish, which make up more of the diet during winter when they are slowed by cold temperatures and are easier to catch. In marine habitats, the diet of African clawless otters is mainly composed of fish. Marine inhabitants also eat crab, Cape rock lobsters, and abalone. African clawless otters have also been known to eat ducks, geese, coots, swans, dragonfly larvae, mollusks, reptiles, small birds, and shrews.
Animal Foods: birds; mammals; amphibians; reptiles; fish; insects; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)
African clawless otters are predators of crabs, fish, frogs, and insects. They are parasitized by several species of flatworm, including Baschkirovitrema incrassatum, Clinostomum pyriforme, and Prudhoella rhodesiensis. In addition, various species of roundworm, including Cloeoascaris spinicollis, spend at least part of their complex life cycle in the tissues of African clawless otters . There are no known ectoparasites.
- Baschkirovitrema incrassatum
- Clinostomum pyriforme
- Prudhoella rhodesiensis
- Cloeoascaris spinicollis
African clawless otters are occasionally eaten by Nile crocodiles and ﬁsh-eagles. Their most dangerous predators are humans. Their bi-colored pelage helps camouflage them with in the water and on land. They are agile swimmers that can often escape potential predators while in the water. While on land, however, they are particularly vulnerable to predation.
- Nile crocodile, (Crocodilus niloticus)
- fish eagle, (Haliaetus vocifer)
- humans, (Homo sapiens)
Anti-predator Adaptations: cryptic
Life History and Behavior
African clawless otters make complex vocalizations, including low and high pitched whistles, grunts, and “hah” sounds thought to express anxiety. They also squeal, moan, and mew. The purpose of different vocalizations is not well understood. These otters demarcate territorial boundaries with scant-marked fecal droppings called "spraints." Spraints are commonly found surrounding dens and occur most frequently during the mating season. A pair of anal scent glands are also used to communicate through scent.
Communication Channels: acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
African clawless otters live 10 to 12 years in the wild and approximately 15 years in captivity.
Status: wild: 10 to 12 years.
Status: captivity: 15 (high) years.
Status: wild: 10 to 14 years.
Status: captivity: 15 years.
Lifespan, longevity, and ageing
Little is known about the mating system of Aonyx capensis.
Little is known of the mating system of African clawless otters. Breeding occurs during the dry season, which varies depending on location, and parturition coincides with the beginning of the rainy season. Gestation lasts approximately 63 days. Litters range in size from 1 to 3 pups, but as many as 5 pups per litter have been reported for animals in captivity. At birth, pups weigh about 200 g and can grow to more than 1,400 g within 14 days. Pups are born altricial but open their eyes and leave their den after 16 to 30 days, and weaning occurs by 45 to 60 days after birth. They become independent and sexually mature by 1 year old.
Breeding interval: A. capensis breeds once a year.
Breeding season: Breeding occurs mainly during the dry season, though copulations may take place year round. .
Range number of offspring: 1 to 5.
Average gestation period: 63 days.
Range weaning age: 45 to 60 days.
Average time to independence: 1 years.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Little is known of parental care in African clawless otters. Mothers nurse their pups until they are 45 to 60 days old. Pups reach independence by the end of their 1st year.
Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Populations of African clawless otters are widespread and stable, and the IUCN Red List of Threatened Species lists them as "least concern". However, human-induced habitat change is a potential threat to some local populations. African clawless otters in Nigeria and Cameroon are listed under CITES Appendix I, while all others are listed under Appendix II.
US Federal List: no special status
CITES: appendix i; appendix ii
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2004Least Concern
Density estimates from various studies in southern Africa are summarized by Somers and Nel (in press). Based on the recovery of radioactive scats, Somers (2001) gives an estimate of 1.53 otters per km of river; assuming there are two otters per km of river, the total population in South Africa alone is estimated at around 21,500 individuals (Somers and Nel in press).
In parts of their range, African Clawless Otters may be killed for skins and other body parts (e.g., Cunningham and Zondi 1991; De Luca and Mpunga 2005), or because they are regarded as competitors for food, particularly in rural areas where fishing is an important source of income, or where they are believed to be responsible for poultry losses (Rowe-Rowe 1995). Fisheries managers of the Kairezi River Protected Area in Zimbabwe blamed trout declines on otter predation and competition with trout for food, even though scat analysis revealed that only 1% of otter faeces contained the remains of trout and their diets overlapped only 17% (Butler 1994; Butler and Marshall 1996). Occasionally, they are accidentally caught and drowned in gill nets and fish traps (Rowe-Rowe 1990).
Relevance to Humans and Ecosystems
Due to their diet, fishermen view African clawless otters as competitors for fish and fish prey. African clawless otters are occasionally viewed as agricultural pests as they also sometimes kill poultry.
African clawless otters are hunted for their pelts and other body parts, and they are occasionally kept as pets.
Positive Impacts: pet trade ; body parts are source of valuable material
African clawless otter
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The African clawless otter (Aonyx capensis), also known as the Cape clawless otter or groot otter, is the second-largest freshwater species of otter. African clawless otters are found near permanent bodies of water in savannah and lowland forest areas. They range through most of sub-Saharan Africa, except for the Congo River basin and arid areas. They are characterized by partly webbed and clawless feet, from which their name is derived.
Aonyx capensis is a member of the weasel family (Mustelidae) and of the order Carnivora. The earliest known species of otter, Potamotherium valetoni, occurred in the upper Oligocene of Europe: A. capensis first appears in the fossil record during the Pleistocene. Aonyx is closely related to the extinct giant Sardinian otter, Megalenhydris.
- A. c. capensis (Schinz, 1821)
- A. c. hindei (Thomas, 1905)
- A. c. meneleki (Thomas, 1903)
- A. c. congica (Lönnberg, 1910)
- A. c. microdon (Pohle, 1920)
- A. c. philippsi (Hinton, 1921)
However, some authorities consider the Congo/Cameroon clawless otter to be a separate species (A. congicus). Under this view, only the first three of the above list would be subspecies of A. capensis.
African clawless otters have thick, smooth fur with almost silky underbellies. Chestnut in color, they are characterized by white facial markings that extend downward towards their throat and chest areas. Paws are partially webbed with five fingers, and no opposable thumbs. All lack claws except for digits 2, 3, and 4 of the hind feet. Their large skulls are broad and flat, with relatively small orbits and short rostra. Molars are large and flat, used for crushing of prey. Male otters are slightly larger than females on average. Adults are 113–163 cm (45–64 in) in length, including their tails that comprised about a third of their length. Weights can range from 10–36 kg (22-80 lbs), with most otters averaging between 12 and 21 kg (26-46 lbs). Despite being closely related to the oriental small-clawed otter, the African clawless otter is often twice as massive as that relatively diminutive mustelid.
African clawless otters can be found anywhere from open coastal plains, to semiarid regions, to densely forested areas. Surviving mostly in southern Africa, the otters live in areas surrounding permanent bodies of water, usually surrounded by some form of foliage. Logs, branches, and loose foliage greatly appeal to the otter as this provides shelter, shade, and great rolling opportunities. Slow and rather clumsy on land, they build burrows in banks near water, allowing for easier food access and a quick escape from predators. In the False Bay area of the Cape Peninsula, they have been observed scavenging along beaches and rocks and hunting in shallow surf for mullet. They are mainly nocturnal in urban areas and lie up during the day in quiet, bushy areas.
Females give birth to litters containing two to five young around early spring. Mating takes place in short periods throughout the rainy season in December. Afterwards, both males and females go their separate ways and return to their solitary lives once more. Young are raised solely by the females. Gestation lasts around two months (63 days). Weaning takes place between 45 and 60 days, with the young reaching full maturity around one year of age.
The diet of Aonyx capensis primarily includes water-dwelling animals, such as crabs, fish, frogs, and worms. They dive after prey to catch it, then swim to shore again, where they eat. Their fore paws come in handy as searching devices and are great tools for digging on the muddy bottoms of ponds and rivers, picking up rocks and looking under logs. Extremely sensitive whiskers (vibrissae) are used as sensors in the water to pick up the movements of potential prey.
Though mostly solitary animals, African clawless otters will live in neighboring territories of family groups of up to five individuals. Each still having its own range within that territory, they mostly keep to themselves unless seeking a mate. Territories are marked using a pair of anal glands which secrete a particular scent. Each otter is very territorial over its particular range.
Awkward on land but acrobats in the water, these animals spend their days swimming and catching food. They return to underground burrows (holts) for safety, cooling or a rubdown using grasses and leaves. Mainly aquatic creatures, their tails are used for locomotion and propel them through the water. They are also used for balance when walking or sitting upright.
Quick in the water and burrowing on land, A. capensis does not have many predators. Its greatest threat comes from the python, which will often lay in wait near or in the water. Other predators would include the crocodile and fish eagles. If threatened, a high-pitched scream is emitted to warn neighboring otters and confuse a predator.
Living in Africa, environments can become very hot. Staying cool means spending time in the water, and using burrows as a way to escape the highest temperatures of the day. To stay warm, on the other hand, the otters depend solely on their thick fur. Guard hairs cover the body, acting as insulation. Since the otter lacks an insulating layer of body fat, its only means of warmth is provided by its thick coat of fur.
The biggest threat to African clawless otters comes from humans. Aonyx specimens will often forage in man-made fisheries and may be hunted or become entangled in nets. Overfishing by humans may reduce the food supply available to otters. They are sometimes hunted for their thick, soft pelts, which humans use in forms of clothing. In forested areas, logging may be a major threat, since erosion leads to greatly increased turbidity in rivers which can in turn greatly reduce the populations of fish on which the otters depend. This may well be a far greater threat to otters than hunting. The Otter Trail is a hiking trail in South Africa named after the African clawless otter, which is found in this area. Otters along the trail are protected, as it falls within the Tsitsikamma National Park.
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