Aonyx capensis capensis

The Cape clawless otter (Aonyx capensis capensis), sub-species of (A. capensis) or generally referred to as African clawless otter is found in Sub-Saharan Africa near permanent bodies of freshwater or can be seen to occupy along the sea coast (2). The Cape clawless otter is the largest of the Old World otters and the 3rd largest of all the otters after the giant otter (Pteronura brasiliensis) and the sea otter (Enhydra lutris).^[1]

Physical Description

The Cape clawless otter is described to have a massive body and a stout tail for an otter ranging from 72 – 91 cm in length and 12 – 21 kg.^[2] Upper lips, sides of face, neck, throat, belly, and edge of ears are all white while the rest of the coat is a brown, chestnut color.^[1] The eyes and ears are small and rounded.^[1] The otter's coat is dense with hairs that can reach 25 mm in length to cover a layer of thick skin.^[1] As noted by the name, the otter's toes are clawless except for digits 2, 3, and 4 of hind feet which have small grooming claws.^[1] The otter's hind feet are partially webbed, but the front feet are not which marks A. capensis as having the least interdigital webbing of all otters.^[1] Notably, the skull of A. capensis is quite large, housing a larger brain in relative size to its body.^[3]

Taxonomy & Phylogeny

As a subspecies of Aonyx capensis, Cape clawless otters are within the genus Lutra and subfamily of Lutrinae. Other otter species included in the Lutrinae subfamily are species such as the Giant otter (Pteronura brasiliensis), the Sea otter (Enhydra lutris), and the North American river otter (Lontra canadensis). The closest relatives on the phylogenic tree to the Aonyx capensis are the Oriental small-clawed otter (Aonyx cinerea) and the Smooth-coated otter (Lutrogale perspicillata).^[3]

Range & Distribution

The Cape clawless otter be found in freshwater habitats that range from South Africa northward to Ethiopia in the east and Senegal in the west.^[1] This species is commonly found in Guinea, Kenya, Liberia, Malawi, Mozambique, Senegal, South Africa, Tanzania, Zaire, and Zimbabwe. However, this species is rare to find in Angola, Benin, Botswana, Burkina Faso, Chad, Guinea-Biaau, Ivory Coast, Sierra Leone, Swaziland, and Uganda. It is very or extremely rare to see this species in Central African Republic, Ethiopia, Ghana, Lesotho, Namibia, Niger, Nigeria, and Rwanda.^[1] A. capensis is absent in ecosystems in central African rain forest region of the Congo basis where A. congicus, of Congo clawless otter is found.^[1]

Behavior & Social Organization

The Cape clawless otter are primarily solitary creatures, but have been seen to travel in family groups.^[1] Density of A. capensis in freshwater habitats ideally reach 1 otter per 2–3 km of stream.^[1] During the day hours, Cape clawless otters typically escape the heat of the sun by hiding in dense vegetation on islands or burrowing underground .^[1] Burrows can reach up to 3 m in depth and have several entrances above or below water.^[1] Dens or burrows include rolling places, spots on the ground where the otter rolls to dry its fur, as well as multiple sprainting sites.^[1] Dens may be reused by several otters in a family group or at separate times.^[1] Breeding season for Cape clawless otters starts around December and with the gestation period of 63 days, litters can be born around February.^[1] Litter size is 1-3 pups that are born with pale, smoky-gray, wooly fur.^[1] Eye-opening for the pups is seen in 16–30 days after which pups are able to venture out of the den.^[1] Weaning occurs at 45–60 days and the young become fully independent of the mother after 1 year.^[1] As with most otters, this otter species have an elaborate vocal repertoire that includes 4 main vocalizations: 2 whistles (1 low-pitched and 1 high-pitched), a grunt, and a variable noise described as a "Hah!" to express anxiety.^[1] Growls and snarls may be given as threats while humming-like noises may be used as a begging call in the pups.^[1] Other sounds may include squeals, mewing, and snuffing noises. Not hunting or after hunting, Cape clawless otters typically emerge from the water to rest upon the shore. Rolling and rubbing is done to dry and groom the fur or can be done to scent-mark areas.^[1] Otters usually bask in the sun or can return undercover to sleep.^[1] Walking on land is awkward for Cape clawless otters so they are observed to either walk slowly or do a seal-like trot. The tail can either be carried off the ground with its tip curving upwards, or dragged on the ground leaving a distinct trail.^[1] These otters are able to carry objects or prey while walking on land by holding them against the chest with one paw while hobbling on three legs.^[1] Carrying offspring on land may results in the female using both front feet to carry the young and then hobble on its back legs.^[1] Due to the awkwardness on land, Cape clawless otters typically spend minimal time travelling on land.^[1]

Feeding & Foraging

In freshwater habitats, the main source of food primarily consists of crabs, frogs, insects, and fish.^[1] Although crabs are available in all of their habitats, other prey in their diet may vary seasonally and change prey availability.^[1] Due to this seasonal change, the Cape clawless otter usually is seen to consume higher amounts of fish in the winter (10-30%) than in the summer (0-10%).^[1] Predation on waterfowl is rarely seen, but in the winter Cape clawless otters have been seen to kill domestic ducks, geese, coots, or swans.^[1]

Conservation status & Threats

To date, the cape clawless otter is not under severe pressure and its conservation status is Red List Category Near Threatened as assessed in 2014 by the IUCN.^[4] Human conflict with this species is mainly change in habitat due to fishing, water pollution, agriculture run-off, and specifically with the introduction of Louisiana crayfish which has altered the prey base in the otter's ecosystem.^[4] Cape clawless otters can be hunted for their pelts, used for medicinal purposes, and in some areas killed as a perceived competitor for fish.^[4] This species is legally protected as stated by the IUCN, but extra efforts towards awareness and protected areas are highly encouraged to the local communities.^[4] Natural predators of the cape otter include crocodiles and fish-eagles, however, most mortality is conflicted by humans (2).

Interesting Facts

If captured at an early age, Cape clawless otters can easily be tamed as pets. After eating, Cape clawless otter cleans its face and feet by dipping paws in water and rubbing face. Cape clawless otters be seen playing by dropping a pebble or small rock in the water and retrieving it before it reaches the bottom or diving with a floating object, releasing it underwater, and watching it float to the surface.

References