Aonyx capensis

Geographic Range

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 congicus , Aonyx capensis does not occur in the central African rainforest region of the Congo basin. Aonyx capensis and A. congicus are sympatric in Uganda and Rwanda.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

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.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial
• saltwater or marine saltwater or marine
• freshwater freshwater

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• rainforest rainforest

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools
• coastal coastal
• brackish water brackish water

• Other Habitat Features
• riparian riparian
• estuarine estuarine

Physical Description

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous 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 female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

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

Behavior

African clawless otters are solitary and can be found in both freshwater and marine habitats. Groups composed of 4 to 6 individuals, with 2 to 3 adults and 2 to 3 young, are occasionally spotted and larger clans sometimes form to forage. These otters are most active during dawn and dusk (i.e., crepuscular). Daytime is spent sleeping in burrows or dens. Nearly half of all dens are formed by natural depressions or sheltering landscape with the other half of dens constructed by otters digging through soft substrates such as sand or mud. The floor of the den is often lined with vegetation. They spend a majority of their waking hours swimming, hunting, foraging, playing, and basking in the sun. On land, these otters either walk slowly or trot like a seal, sometimes walking over 7 km between bodies of water. They swim by using their hind legs and tails for propulsion while using their tails as rudders.

African clawless otters do the majority of their hunting in water. Shallow water, approximately 1.5 m deep, is preferred for hunting. They begin hunting by submerging their heads underwater and scanning for prey while using their forefeet to feel under rocks. They grab prey with their forefeet and bring it to the surface to eat. Small crabs are eaten while the otter is perpendicular to the water’s surface, and large crabs are eaten while the otter lies on its back in order to catch pieces of food falling from its mouth. African clawless otters also dive for fish. Dives can last from 6 to 49 s, averaging 18 s per dive. Small fish are eaten in the water, and large fish are brought to shallow water or the shore for consumption. Directly after eating, African clawless otters clean their faces with their forefeet. After hunting bouts they may exit the water and dry off or spend time playing. They dry themselves off by rolling and rubbing their bodies against grass, rocks, or sandbars and basking in the sun. Young African clawless otters spend a significant amount of time playing and have been observed play-fighting, swimming, sliding on rocks, playing with their food, and even fetching small pebbles thrown into the water before they hit the ground.

• Key Behaviors
• natatorial natatorial
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

African clawless otters have home ranges from 4.9 ha to 1062.5 ha. Most of their time is spent in a smaller core area ranging from 1.1 ha to 138.9 ha.

Communication and Perception

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 acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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 .

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• fish
• insects
• mollusks
• aquatic crustaceans

Predation

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.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

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.

Economic Importance for Humans: Positive

African clawless otters are hunted for their pelts and other body parts, and they are occasionally kept as pets.

• Positive Impacts
• pet trade pet trade
• body parts are source of valuable material

Economic Importance for Humans: Negative

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.

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.

Additional Links

Encyclopedia of Life

Contributors

Daniel Kowalsky (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff.

References

Hoffmann, M. 2010. "Aonyx capensis" (On-line). IUCN Red List of Threatened Species. Accessed April 01, 2011 at http://www.iucnredlist.org/apps/redlist/details/1793/0 .

Jacques, H., G. Veron, F. Alary, S. Aulagnier. 2009. The Congo Clawless Otter (Aonyx congicus) (Mustelidae: Lutrinae): A Review of Its Systematics, Distribution and Conservation Status. African zoology , 44/2: 159-170. Accessed March 14, 2011 at http://dx.doi.org/10.3377/004.044.0204 .

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 .

Parker, D. 2005. The diet of Cape clawless otters at two sites along the Bloukrans River, eastern Cape Province, South Africa. African zoology , 40/2: 330-334.

Perrin, M., C. Carugati. 2000. Food habits of coexisting Cape clawless otter and spotted-necked otter in the KwaZulu-Natal Drakensberg, South Africa. South African Journal of Wildlife Research , 30/2: 85-92.

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.

Somers, M., J. Nel. 2004. Movement patterns and home range of Cape clawless otters (Aonyx capensis), affected by high food density patches. Journal of zoology , 262/1: 91-98. Accessed March 10, 2011 at http://sfx.lib.umich.edu:9003/sfx_local?sid=CSA%3Azooclust-set-c&pid=%3CAN%3EZOOR14005029188%3C%2FAN%3E%26%3CPY%3E2004%3C%2FPY%3E%26%3CAU%3ESomers%2C%20M.J.%20%7Ba%7D%3B%20Nel%2C%20J.A.J.%3C%2FAU%3E&issn=0952-8369&volume=262&issue=1&spage=91&epage=98&date=2004-01&genre=article&aulast=Somers&auinit=MJ%7Ba%7D&title=Journal%20of%20Zoology%20%28London%29&atitle=Movement%20patterns%20and%20home%20range%20of%20Cape%20clawless%20otters%20%28Aonyx%20capensis%29%2C%20affected%20by%20high%20food%20density%20patches .

Wotton, S., T. Morris, G. Anderson, G. Shorrock. 2010. Threatened species surveys in the Gola Forest Reserves, Sierra Leone. Ibis , 152/1: 205-206.