Overview

Brief Summary

Biology

Within its aquatic habitat, the African clawless otter searches for food with its dexterous hands, overturning rocks, churning up mud, and probing vegetation for crustaceans, molluscs, frogs, fish and water tortoises (4) (5). Once captured, the otter may float in the water whilst eating its prey, or take larger items ashore (4). Often this activity is undertaken solitary, but sometimes groups of up to eight African clawless otters may be seen, usually either a mother with her cubs, or a group of males (4). African clawless otters use a number of sites out of the water to rest and sleep. Often these may be situated amongst thick vegetation or amid rocks, but they may also dig underground dens that are up to three metres long and contain a grass-lined nest (4). This otter may breed at any time of the year, giving birth to a litter of one to three cubs after a gestation of 63 days. At just one year of age, the young African clawless otters are independent (4). African clawless otters leave a number of noticeable clues to their presence as they move about their habitat. The large, long, clawless footprints are unmistakable, and deposits of faeces and urine are often left as they travel as a means of communicating with other otters. The African clawless otter also emits a variety of whistles, huffs, growls and screams with which it communicates to other individuals (4).
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Description

The dexterous, hand-like forefeet of the African clawless otter are its most remarkable feature, enabling it to grapple with its prey with notable ease. The forefeet have long fingers, rounded finger tips and, as its name describes, lack any claws (4) (5). The hindfeet are also clawless, but unlike the forefeet, have webbing between the digits (5). Also making the African clawless otter a proficient predator is its large skull, which houses powerful jaws and large, broad molars with which to crush its prey (2) (4). The sleek coat of this large otter is dark chocolate brown on the upperparts, lighter below, and creamy white on the throat (2) (4), and numerous conspicuous white whiskers frame the face (4).
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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. 

For more information on MammalMAP, visit the MammalMAP virtual museum or blog.

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Distribution

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 )

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Range Description

The African Clawless Otter is the most widely distributed otter species in Africa, with a range stretching from Senegal and Mali throughout most of West Africa to Sudan and Ethiopia, and then southwards throughout East Africa to the Western Cape of South Africa. They are absent from the Congo basin, where they are replaced by the Congo Clawless Otter Aonyx congicus, the two species being sympatric in Uganda and Rwanda (Somers and Nel in press).
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Range

The most widely distributed otter in Africa, the African clawless otter ranges from Senegal, through most of West Africa to Ethiopia, and south to South Africa (1). Overall, it may occur in any large areas of suitable habitat south of the Sahara, except for the Congo Basin (4).
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Physical Description

Morphology

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

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Ecology

Habitat

The African clawless otter is an inhabitant of a wide range of freshwater habitats, including lakes, streams, rivers and estuaries (5). It may also be found in marine habitats, such as along rocky seashores if there is access to freshwater, which is essential for drinking and washing (1) (4). Although most often found in water, the African clawless otter is also capable of travelling long distances overland (4).
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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

  • Nel, J., M. Somers. 2007. Distribution and habitat choice of Cape clawless otters, in South Africa. South African Journal of Wildlife Research, 37/1: 61-70. Accessed March 10, 2011 at http://dx.doi.org/10.3957/0379-4369-37.1.61.
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Habitat and Ecology

Habitat and Ecology
African Clawless Otters are predominantly aquatic and seldom found far from water. Freshwater is an essential habitat requirement, and they only occur in marine habitats provided there is access to fresh water. In marine habitats, rocky shores are preferred (Van Niekerk et al. 1998). Elsewhere, they are found in diverse habitats, from impoundments, estuaries, and mangroves to desert conditions of the upper Doring River in the Western Cape and the Fish River in southern Namibia (Nel and Somers 2007; Somers and Nel in press); they are also found in many seasonal or episodic rivers in the Karoo, such as the Sak, Vis, Riet and Gamka Rivers, provided suitable-sized pools persist (Nel and Somers 2007; Somers and Nel in press). They have been recorded up to 3,000 m in Ethiopia (Yalden et al. 1996). African Clawless Otters have been found in towns and cities, and can occupy rivers with high pollution and eutrophication levels (Somers and Nel in press).

Systems
  • Terrestrial
  • Freshwater
  • Marine
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Trophic Strategy

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)

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Associations

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.

Commensal/Parasitic Species:

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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.

Known Predators:

  • Nile crocodile, (Crocodilus niloticus)
  • fish eagle, (Haliaetus vocifer)
  • humans, (Homo sapiens)

Anti-predator Adaptations: cryptic

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Life History and Behavior

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

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Life Expectancy

African clawless otters live 10 to 12 years in the wild and approximately 15 years in captivity.

Range lifespan

Status: wild:
10 to 12 years.

Range lifespan

Status: captivity:
15 (high) years.

Typical lifespan

Status: wild:
10 to 14 years.

Average lifespan

Status: captivity:
15 years.

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Lifespan, longevity, and ageing

Maximum longevity: 14.2 years (captivity) Observations: One specimen of the *congicus* subspecies lived 14.2 years in captivity (Richard Weigl 2005). Anecdotal reports suggest these animals may live up to 16 years.
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Reproduction

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)

  • Larivière, S. 2001. Aonyx capensis. Mammalian Species: 1-6. Accessed March 10, 2011 at http://dx.doi.org/10.1644/1545-1410(2001)671<0001:AC>2.0.CO;2.
  • Nel, J., M. Somers. 2007. Distribution and habitat choice of Cape clawless otters, in South Africa. South African Journal of Wildlife Research, 37/1: 61-70. Accessed March 10, 2011 at http://dx.doi.org/10.3957/0379-4369-37.1.61.
  • Somers, M., J. Nel. 2003. Diet in relation to prey of Cape clawless otters in two rivers in the Western Cape Province, South Africa. African zoology, 38/2: 317-326.
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Conservation

Conservation Status

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

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Hoffmann, M.

Reviewer/s
Hussain, S.A. (Otter Red List Authority) and Hoffmann, M. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Least Concern as the species is widespread, most populations are believed to be stable, and there are no major threats resulting in a range-wide population decline that would warrant listing in a threatened category.

History
  • 2004
    Least Concern
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Status

Classified as Least Concern (LC) on the IUCN Red List (1) and listed on Appendix II of CITES (3). Populations of the subspecies Aonyx capensis microdon in Cameroon and Nigeria are listed on Appendix I of CITES (3).
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Population

Population
African Clawless Otters are fairly common to rare, with populations thought to be stable in 29 of the 35 countries from which they have been recorded (Rowe-Rowe 1990, 1995; Nel and Somers 2002). Abundance appears to be dependent on the availability of crabs (Rowe-Rowe and Somers 1998).

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).

Population Trend
Stable
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Threats

Major Threats
There are no major threats to the species; however, in some parts of their range, their habitat has been either drastically changed or lost, following bush clearing, deforestation, overgrazing, siltation, draining of wetlands or water extraction or denudation of riparian vegetation (Rowe-Rowe 1995; Nel and Somers 1998).

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).

.
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In some areas of its large range, the African clawless otter is killed for its sleek fur, or for other body parts that are used in traditional medicines (1) (4). It may also be persecuted due to the belief that this otter competes for fish with humans, or because it is blamed for the death of domestic ducks, hens, or the raid of a fish farm (1) (4). Occasionally, African clawless otters may occasionally become entangled in fishing nets, and drown (1). The African clawless otter may also be impacted in some areas by the degradation or loss of its habitat. Deforestation, development, overgrazing, the draining of wetlands, and water extraction all have a detrimental impact on the quality of its aquatic habitat and the surrounding vegetation (1) (4).
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Management

Conservation Actions

Conservation Actions
African Clawless Otters are present in a number of protected areas across their range. The populations of Cameroon and Nigeria are listed on CITES Appendix I ( as Aonyx capensis microdon). All other populations are included in CITES Appendix II.
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Conservation

Despite the rather numerous threats facing this species in certain parts of its range, none are believed to be great enough to result in the African clawless otter being threatened with extinction (1). It has been recorded in degraded river habitats, where there are high levels of pollution or eutrophication, as well as in towns and cities (1), which demonstrates that this species may have some resilience to man-made changes to its habitat. The African clawless otter also occurs in a number of protected areas across its range (1).
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Relevance to Humans and Ecosystems

Benefits

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.

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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

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Wikipedia

African clawless otter

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.[2] They are characterized by partly webbed and clawless feet, from which their name is derived.

Taxonomy[edit]

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.[3] Aonyx is closely related to the extinct giant Sardinian otter, Megalenhydris.

Subspecies[edit]

Mammal Species of the World lists six subspecies of Aonyx capensis:[1]

However, some authorities[2][3] 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.

Description[edit]

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).[4][5] Despite being closely related to the oriental small-clawed otter, the African clawless otter is often twice as massive as that relatively diminutive mustelid.

Habitat[edit]

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.

Reproduction[edit]

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.

Diet[edit]

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.

Behavior[edit]

African clawless otter in Toledo Zoo, Ohio

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.

Predation[edit]

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.

Thermoregulation[edit]

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.

Economic impact[edit]

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.

References[edit]

  1. ^ a b Wozencraft, W. C. (2005). "Aonyx capensis". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 532–628. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  2. ^ a b c Hoffmann, M. (2008). "Aonyx capensis". IUCN Red List of Threatened Species. Version 2010.2. International Union for Conservation of Nature. Retrieved 2 Aug 2010. 
  3. ^ a b Larivière, Serge (5 June 2001). "Aonyx capensis". Mammalian Species 671: 1–6. doi:10.1644/1545-1410(2001)671<0001:ac>2.0.co;2. 
  4. ^ [1] (2011).
  5. ^ [2] (2011).
  • Michael J. Somers and Jan A. J. Nel. 2004. Habitat selection by the Cape clawless otter (Aonyx capensis) in rivers in the Western Cape Province, South Africa, African Journal of Ecology 42: pg 298-305.
  • Michael J Somers. 2000 Foraging Behavior of Cape Clawless Otters (Aonyx capensis) in a marine habitat., Journal of Zoology, 252: pg 473-480.
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