Aonyx capensis (Schinz, 1821)
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publication ID |
https://doi.org/ 10.5281/zenodo.5714044 |
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DOI |
https://doi.org/10.5281/zenodo.5714121 |
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persistent identifier |
https://treatment.plazi.org/id/038F87D4-CA4A-FFA4-CFE8-3488FAF0F3C7 |
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treatment provided by |
Conny |
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scientific name |
Aonyx capensis |
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African Clawless Otter
French: Loutre a joues blanches / German: Fingerotter / Spanish: Nutria africana
Other common names: Cape Clawless Otter, Congo Clawless Otter
Taxonomy. Lutra capensis Schinz, 1821 View in CoL ,
Cape of Good Hope.
The Congo Clawless Otter ( Aonyx congicus ) is considered a separate species by some authors, based on morphological and ecological evidence; however, further research is needed to determine its taxonomic status. It is here included as a subspecies of A. capensis . Two subspecies are recognized.
Subspecies and Distribution.
A. c. capensis Schinz, 1821 — Sub-Saharan Africa from Senegal in the W to E Ethiopia, and E Africa to Western Cape. Absent from Congo Basin and the most arid zones of Namibia, Botswana, and South Africa.
A. c. congicus Lonnberg, 1910 — Congo Basin in WC Africa. View Figure
Descriptive notes. Head-body 76.2-88 cm (males), 73-73.6 cm (females), tail 46-5— 51- 5 cm (males), 49.5-51.5 cm (females); weight 10-21 kg (males), 10.6-16.3 kg (females), adult males are larger and heavier than females. The African Clawless Otteris large and heavily built. The pelage is dark brown to black throughout, but the sides of the face, neck and throat are white or pale gray. There is a quadrangular dark brown patch between the eye and the nose; the cheeks are white. The hindfeet are partially webbed, but the front feet are not. The toes are clawless except for the three middle toes of each hindfoot, which bear small grooming claws. The cheek teeth are smaller in congicus than in capensis . Dental formula: 13/3, C1/1,P 4/3, M 1/2 = 36.
Habitat. African Clawless Otters are mainly found in rainforests and lowland swamp forests, but may also inhabit forested rivers and streams in open coastal plains and semi-arid country. They occur mostly in fresh water; some populations inhabit saltwater coasts, but because they require fresh water to drink, even coastal populations occur near freshwater tributaries. They also occupy many natural or man-made lakes and reservoirs, but prefer areas of shallow water. In South Africa, African Clawless Otters prefer riverine habitats covered with dense vegetation, while areas of short grass are avoided. They also select areas with boulders and/or reed beds, which provide high crab density and shelter. In southern Nigeria, African Clawless Otters are mainly restricted to brackish streams (with mangrove vegetation along the banks) and, more occasionally, transitional habitats between freshwater and brackish-water environments.
Food and Feeding. African Clawless Otters are primarily crab eaters, but other foods such as frogs, fish, and insects are consumed. Fish increases in importance in the diet during winter, when they are lethargic and easier to capture. Lobsters, octopus, and shellfish are eaten along the seacoast. In two reserves in the Eastern Cape Province, South Africa, the diet was more varied at Mkambati (15 prey species) than Dwessa (seven species). In terms of relative percentage frequency of occurrence, the spiny lobster (Panulirus homarus) was found to be the most common prey item at both Mkambati (37-9%) and at Dwessa (35-2%), followed by fish (31% and 36-6%, respectively), crabs (22:4% and 19-7%) and molluscs (3-1% and 4-2%). Lobster and fish are relatively abundant within these reserves, suggesting prey availability rather than selective feeding influenced diet. At another site in the Eastern Cape Province, the three most common prey categories found in otter spraints were the crab Potamonaules perlatus (51%), insects (19%), and the fish Tilapia sparrmanii (18%). At Betty’s Bay, South Africa, fish are the most important prey category (59% of the biomass), followed by octopus (15%), red rock crab Plagusia chabrus (13%), cape lobsterJasus lalandii (10%), and the brown rock crab Cyclograpsus punctatus (0-8%). In eastern Zimbabwe, the diet is mainly the river crab Potamon perlatus (42%). African Clawless Otters use various hunting methods. In shallow or murky water, they detect crabs with their forefeet as they feel around underwater rock crevices. Prey is grabbed with the forefeet and then bitten and eaten. In shallow but clear water, African Clawless Otters may immerse their heads and scan for prey visually while feeling under rocks with the forefeet. In deeper water, they dive straight down and can remain underwater for up to 50 seconds. African Clawless Otters eat small prey while they swim upright at the surface, whereas larger prey are taken to shore for consumption. In South Africa, African Clawless Otters were observed to select open water within 8 m of the shore. Foraging involved moving into shallow water (c. 0-2 m deep) and walking along the substrate feeling for prey with the forefeet. African Clawless Otters prefer hunting at depths of 0-5- 1- 5 m.
Activity patterns. Mainly nocturnal, but may be active during the day in areas remote from human disturbance. Rest sites are in burrows (holts), under large rocks or root systems, or in dense vegetation near water; they may dig their own burrows. In South Africa, the occurrence of spraints, couches and resting places is closely tied to freshwater sources; holts are located adjacent to river banks, oxbow lakes, or dam shores, and spraint sites are found in dense, tall grass cover beside water less than 1 m deep. In the Tsitsikama Coastal National Park, South Africa, the activity at several holts indicated about 32% utilization, with an estimated one otter to every three holts.
Movements, Home range and Social organization. African Clawless Otters are highly mobile and nightly movements may reach 13 km. Although mostly solitary, family groups comprising one female with her young, or groups of males, may occur. Home ranges are estimated at 14-20 km ”. In South Africa, a radio-tracked adult male had a minimum home range of 19- 5 km of coast, with a core area of 12 km; an adult female had a 14-3 km-long home range, with a 7- 5 km core area. Apparently, there was a clantype social organization, with groups of related animals defending jointterritories. In another area in South Africa, total range length varied from 4-9 to 54- 1 km and core length from 0-2 to 9- 8 km; the total area of water used varied between 4-9 and 1062-5 ha, and core areas from 1-1 to 138-9 ha. The pattern of home range use by females was suggestive ofterritoriality, whereas male otters had overlapping home ranges, both with other males and females. Population densities vary with food abundance (especially crabs) and range from 2-7 otters per 10 km of coastline or stream. Along the coast of South Africa, the mean population density was one per 1-9 km and dens were spaced at intervals of 470 m.
Breeding. Mating may occur anytime during the year, but most births occur during the start of the rainy season. Births have been recorded in July and August in Zambia, and young have been found in March and April in Uganda. There appears to be no set breeding season in West Africa. Most births in a coastal area of South Africa occurred in December and January. Gestation lasts 63 days. The litter size is one to three. The young are born blind, but with some fur. Their eyes open after 16-30 days, and weaning occurs after 60 days. Sexual maturity is reached during the first year.
Status and Conservation. CITES Appendix I and II. Classified as Least Concern in The IUCN Red List; the Congo Clawless Otter (congicus) is also listed as Least Concern. Habitat alteration and water pollution are the main threats to this species, asit affects the abundance of crabs and other prey. Additionally, the African Clawless Otter is hunted for its pelt and medicinal purposes in some areas and killed in others as a perceived competitorfor fish, particularly where the Rainbow Trout has been introduced.
Bibliography. Angelici et al. (2005), Arden-Clark (1986), Baranga (1995), Carugati et al. (1995), Emmerson & Philip (2004), Kingdon (1971-1982), Ligthart et al. (1994), Nel & Somers (2007), Perrin & Carugati (2000), Purves et al. (1994), Reuther et al. (2003), Roberts (1951), Rosevear (1974), Rowe-Rowe (1977a, 1977b, 1992a, 1995), Rowe-Rowe & Somers (1998), Somers (2000), Somers & Nel (2004), Somers & Purves (1996), Stuart (1981), Van der Zee (1981, 1982), Van Niekerk et al. (1998), Verwoerd (1987), Watson & Lang (2003), Wozencraft (2005).
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