Aonyx capensis congica

Geographic Range

Congo clawless otters are found in the lower Congo basin, which lies between southeastern Nigeria and western Uganda.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Congo clawless otters reside exclusively in the small swamps, ponds, and streams of heavy rainforests. Due to their amphibious lifestyle, these otters are both excellent swimmers and skilled explorers of the shores (Kingdon, 1982). Their hair type, reduced vibrissae, and rather generalized dental morphology suggest that they may be more terrestrial than other otter species (Nowak, 1999).

• Habitat Regions
• tropical tropical

• Terrestrial Biomes
• rainforest rainforest

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Wetlands
• swamp swamp

Physical Description

Aonyx congicus is a large, powerfully built otter, though it is more slender in the neck and back than other populations of Aonyx capensis . Head and body length ranges between 78 and 97 cm, with the tail adding an additional 40 to 59 cm to the total length. Weights range from 15 to 25 kg in adult animals.

These otters have a dark, chestnut-brown coat with some silver frosting on the head and neck, contrasted by a white chest, nose and ears. A distinctive black patch is located between the eyes and nostrils (Kingdon, 1982). Aonyx congicus young resemble the adults except for a greater frosting of the coat. Unlike many other otter species, A. congicus has no claws, no webbing in the manus, and webbing only halfway down the digits in the pes. All are adaptations to improve dexterity and tactile sensitivity for foraging in the muddy waters of the lower Congo basin. The less specialized dentition of A. congicus , when compared to the broader species, A. capensis , serves as a distinguishing characteristic and suggests a broader carnivorous diet than other populations (Haltenorth and Diller, 1980).

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

• Sexual Dimorphism
• sexes alike

Reproduction

Very little has been recorded about the mating habits of Congo clawless otters. They remain enigmatic as their elusive nature and remote range have prevented many of their behaviors from being described (Estes, 1991). One could infer that the mating system is similar to other African otter species, where there is a short-lived monogamy followed by a return to a more solitary lifestyle (Chanin, 1985).

• Mating System
• monogamous monogamous

Nothing is known with certainty about the reproductive behavior of A. congicus . It has been suggested that the gestation period is around two months, that an average of two to three young are born per litter, and that young do not reach sexual maturity until about one year of age (Nowak, 1999). Although it is not known whether the breeding is seasonal or occurs throughout the year, births do seem to peak in the dry season in other Aonyx capensis populations, and it is predicted that A. congicus would be similar (Estes, 1991).

Despite a paucity of information on the development and reproduction of these otters, we can reasonably infer that they are similar to other members of the genus Aonyx . Aonyx cinerea has an estruous cycle that lasts between 22.4 and 30 days, and an estrus of 3 days. Because the gestation period is between 60 and 64 days, they can produce two litters per year. The young are altricial, and do not open their eyes until the age of 40 days. Young are able to swim by the age of 9 weeks, and eat solid foods after 80 days.

• Key Reproductive Features
• iteroparous iteroparous
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

Much of the parental behavior in Congo clawless otters is unknown. The mother is the primary care giver, but it is unclear to what degree the male is involved in rearing young (Nowak, 1999). Although we may infer that the mother provides young with milk, shelter, and grooming during their period of dependency, the duration of care is a mystery. Further, there is very little documentation on other members of the genus; observed males of the same subfamily, Lutrinae , show varying degrees of care. Though often solitary creatures, Congo clawless otters have been observed foraging as family parties. However, it is hypothesized that these associations are transient and based more on territory sharing and overlapping rather than a post-independence affinity for their family members (Haltenorth and Diller, 1980).

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Lifespan range in A. congicus is unknown. Captive specimens of the larger species, A. capensis , and the related species, A. cinerea , have lived as long as 14 and 16 years respectively (Nowak, 1999).

Behavior

Congo clawless otters are mostly nocturnal, but have been observed in undisturbed swamp lands during the daytime. Though mostly solitary, family groups have also been observed along the rivers of Cameroon (Kingdon, 1982). The social organization of A. congicus is not well understood. In other A. capensis populations, individuals defend territories of around twelve square kilometers that often overlap with three or more other adult males (Nowak, 1999).

• Key Behaviors
• terricolous
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial

Home Range

The home range size of A. congicus is not known. In other A. capensis populations, home ranges are between four and six square kilometers (Chanin, 1985).

Communication and Perception

No form of communication has been specifically documented for A. congicus . Clawless otters , in general, communicate vocally with chirps, squeals, and purring noises when expressing affection or play. Often growls, snarls, and a screaming wail are signs of displeasure or apprehension. Clawless otters also use strong olfactory cues to communicate. They musk their coats and produce a sticky feces, capable of clinging to vertical surfaces, to mark the boundaries of their territory. The visual aspects of communication, including body language, are mostly undescribed (Estes, 1991). Tactile communication is undoubtedly of some importance in reproduction, especially between mates and between a mother and her offspring.

• Communication Channels
• visual visual
• tactile tactile
• 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

Aonyx congicus is known to have a broad carnivorous diet, consisting of crabs, mollusks, fish, frogs, and other small vertebrates and invertebrates found in the shallow rivers and muddy shores of the Congo river basin. Its streamlined, powerful body propels it after the aquatic prey of rivers and ponds. Its specially adapted fingers are sensitive and dexterous, well suited for overturning stones, grasping prey, and sifting through the muddy shores of streams and swamps for invertebrates (Kingdon, 1982). Aonyx congicus has also been observed hunting in the tangled reeds and shoots of riverside vegetation, actively stalking small terrestrial vertebrates from cover (Haltenorth and Diller, 1980).

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

• Animal Foods
• mammals
• amphibians
• fish
• eggs
• mollusks
• terrestrial worms
• aquatic crustaceans

Predation

The dark chestnut coat of A. congicus acts as a form of camouflage within the muddy swamps and rivers of the Congo basin. The coloration may protect A. congicus from predation by the crocodiles, pythons, eagles, and leopards in this habitat (Kingdon, 1982). Although there is no documentation of predation on Congo clawless otters, other otter species are taken by large snakes, crocodilians, large cats, and birds of prey (Berry, 2000). It is reasonable to assume that similar predators take A. congicus .

Although it is not illustrated or described for A. congicus , the arched posture, snarled facial expressions, and harsh vocalizations of a defensive otter are commonly observed in the genus Aonyx (Estes, 1991).

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Within the rainforest ecosystem, A. congicus acts as a predator, preying on crustaceans, fish, frogs, and other small vertebrates and invertebrates. It is also a possible prey animal for pythons, leopards, eagles, and crocodiles (Kingdon, 1982).

Economic Importance for Humans: Positive

If captured when young, their relatives, Aonyx cinerea have proven intelligent pets and have been trained to catch fish for Malay fishermen. Aonyx congicus has been commercially hunted for its beautiful coat as well. Though the fur quality is considered not as high as other otter species.

• Positive Impacts
• body parts are source of valuable material

Economic Importance for Humans: Negative

Aonyx congicus has no known negative effects on the economy. However, if provoked, clawless otters have been known to sever fingers from the hands of humans with their bite. They have also attacked and drowned dogs that tread too closely to them (Estes, 1991).

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

The most likely causes for the endangered status of A. congicus are habitat loss and pollution due to development in the Congo basin as well as chronic over-harvesting for fur (Nowak, 1999).

Other Comments

Much of the natural history of A. congicus remains a mystery at this point. Most of what is currently help to be true of these animals has been constructed from fragmentary field observations and assumptions based on other populations of A. capensis , which are also poorly understood. Aonyx capensis congica was previously considered a species, A. congicus , but range overlap and similarities with A. capensis resulted in their being considered a population of A. capensis .

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Barbara Lundrigan (editor, instructor), Michigan State University, Daniel MacArthur (author), Michigan State University.

Nancy Shefferly (editor), Animal Diversity Web.

References

Berry, K. 2000. "Animal Diversity Web" (On-line). Accessed April 09, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lontra_longicaudis.html .

Chanin, P. 1985. The natural history of otters . London: Croom Helm.

Estes, R. 1991. The behavior guide to African mammals : including hoofed mammals, carnivores, primates / Richard Despard Estes ; drawings by Daniel Otte ; foreword by E.O. Wilson . Berkeley: University of California Press.

Haltenorth, T., H. Diller. 1980. A field guide to the mammals of Africa, including Madagascar / Theodor Haltenorth, Helmut Diller ; translated by Robert W. Hayman . London: Willliam Collins Sons and Co Ltd.

Harris, C. 1968. Otters: a study of the recent Lutrinae . London: Weidenfeld & Nicolson.

Kingdon, J. 1982. East African Mammals: an atlas of evolution in Africa . London, New York: Academic Press.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition . Baltimore and London: The Johns Hopkins University Press.