ECOLOLOGY OF SOUTH AFRICAN OTTERS, THE AONYX CAPENSIS AND HYDRICTIS MACULICOLLIS
According to Rowe-Rowe, (1978) South African otters the Cape clawless otter or African clawless otter (Aonyx capensis) and spotted-necked otter (Hydrictis maculicollis) travel manly in aquatic habitat to another, neither of the otters is adapted at terrestrial, they try to keep land travel to a minimum. Otters dry and groom themselves by rolling and rubbing against inanimate object. Shelter is taken in holes in the ground and beneath rocks, roots of trees, or in clustered vegetation on islands (Arden-Clarke, 1986). The uncontrolled exploitation in the marine for fur trade declined the species close to extinction by the early
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When offered various fish species they caught them in inverse proportion to the fishes swimming ability, as do other otter species. Small fish were captured more readily than large fish. In freshwater areas, spotted-necked otters took almost equal amount of fish and crabs, overall crabs, however were the major item in spring, summer, and autumn with fish assuming importance in winter since crabs are inactive and remain deeply hidden during winter while fish move more slowly in the cold weather. This indicate a much higher proportion of fish in the diet, the fish fauna of Natal is impoverished, so that local spotted-necked otter must have adapted to an increased diet of crabs. Frogs made up most of the remainder of the diet. Crabs are much more important to A.capensis which took relatively few fish in Natal. Frogs are also important because they were taken in greater numbers in winter when crabs became inactive. The crabs taken by H.maculicollis were generally small , whereas A.capensis took all sizes (Tomlinson, 1974). Rowe-Rowe, (1977c) concluded that the food overlap between Aonyx and Hydrictis was …show more content…
H. G., 1986, Population density, home range size and special organisation of the Cape clawless otter, Aonyx capensis, in a Marine Habitat, Journal of Zoology, London, 209, 201-211.
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It was also observed that there was no decline in horseshoe crabs and in fact, the population has held steady with the likelihood of
of food per day for some large male otters. Their diet being mainly sea urchins, the sea otters keep the urchin population under control which allows for other life within the kelp ecosystem to survive and create a balanced ecosystem. Without the sea otters in a kelp ecosystem, the sea urchins can take over and disrupt the ecosystem by killing out some algae species and some fish which live in the
The Hawaiian Monk Seal (Neomonachus schauislandi) is a primitive, non-migratory phocid endemic to the islands of Hawaii (National Marine Fisheries Service, 2007). These primarily aquatic pinnipeds spend two-thirds of their lives in the water but require some land, often sandy beaches, to haul-out for reproduction and rest (NMFS, 2007). Monk seals have a polygynous mating structure but precise mating behavior and dominance establishment is unknown because they are aquatic processes not often observed (Jefferson et al., 1993). Females begin giving birth around age five to nine with each female producing a single pup every year (Johanos et al., 1994). After giving birth, females will stay and nurse their pups while fasting and energetically supporting
Mammalogy. Adaptation, Diversity, and Ecology. WCB McGraw-Hill, Boston.563pp 4. Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2017. The Animal Diversity Web (online).
This predation was seen at Hastings Point, where the limpet’s main predator, Morula marginalba (mulberry whelk), was identified 25 times in the first 35m. To survive this predation, the limpet utilises its tough clutch on the rocks, defending itself against predators by trapping them under the rim of its shell, consequently killing or starving the
Today otters face other threats. Apart from disease epidemics, otters continue to be threatened by overharvest, interactions with fisheries (e.g. gear entanglements), oil spills and being prey to killer
River otters have beautiful coats and thus they have been hunted by many people. They mainly eat fish, but they eat many other easily accessible things, like shellfish, crustaceans, mollusks, oysters, birds, rodents, and frogs. Their population is hard to tally, but has been estimated to be over 100,000 based on harvest reports. River otters may be found in all states and territories of the U.S. and Canada. They will only settle into an area amidst concealing structures, generally consisting of foliage or rock piles.
The author states that the pollution hypothesis seemed the most likely cause of otters decline along the Alaskan coast and provides three reasons. In contrast, the professor states that the ongiong investigation show that the predation theory is mst likely the cause of the decline and sh.e opposes each of the author 's reasons First, the reading claims that there were known sources of pollution along the Alaskan coast. However, the professor refutes this pint by saying that the pollution theory is weakened by that no dead sea otters were washed up to the shore. She said thet if the infection is the cause of the decline, there should be a lot of killed otters washed up, so this fact is consistent with the predation theory because if the sear otters were killedby predetors, they would not wash up to the shore.
There is always a new bandwagon for false activists, and one of the most popular is the cause of freeing captured killer whales. For some, this is not just the latest fad, but it has been a life long devotion which has been the focus of their passion since the mid twentieth century. These creature are majestic and need to be protected. They were named after this frightening figure because of their brutal reputation in the wild. In Latin, the word Orca can literally be translated to barrel-shaped, thus referring to the large and cylindrical shape of the killer whale 's body.
The illegal hunting and trade of primate meat is a large contributing factor to the decline of primate species in the tropics. This, in addition to habitat loss and fragmentation, disease, and the pet trade, is putting many primate species at high risk of extinction. Poverty, population growth, construction of roads, emergence of regional and international markets, and new hunting technology are triggering the increased hunting pressure on forest mammals. Primate species are especially vulnerable to increased hunting pressure because of their slower reproductive cycles. The decline of primate species must be stopped to avoid their extinction and the potential consequences that this could have for tropical forests.
The article states that there is a rapid decline in the population of sea otters, the mammals found along the coast of California to Alaska. The article claims that the reason for the declination is because of environmental pollution and provides two reasons of support. However, the speaker refutes that the dwindling is due to predation. First, the reading claims that environmental pollution is the most likely cause because oil rigs found along the coast cause pollution to a greater extent.
A Study Case of Amazonian Calf Interactions Introduction The Amazonian manatee is a very well known and loved species of manatee. Out of all of the Manatee species the Amazonian manatee is the smallest that utilizes only fresh water habitats. It has a fairly limited habitat that falls in the Amazonian Basin 's rives and lakes.
Although the orca can be found in both in the open ocean and in the coastal waters, they primarily inhabit the continental shelf’s in the water less than 200 meters deep. In the cold water area is the most distribution limited by the seasonal pack ice. The killer whale is the top carnivore consumer on the food web. Killer whales may be large in size and appetite, but they still act on instinct and have no desire to kill intentionally. The killer whale is also a very playful and intelligent creature like most dolphins are, therefore they do not deserve the name killer whale.
The two graphs shows the diving patterns of transient and resident killer whales within a three hour range after midnight. It also shows the depth of the ocean where the certain killer whale is traveling to. I believe that graph A represents resident killer whales and graph B represents transient killer whales. In graph A, the average bottom depth is from 75 to 125 meters, except for one spike at a shallow depth of around 35 meters.
Running To Survive Imagine running for your life, everyday, from the moment you wake up. Wild animals must do this in order to survive. Some animals run away from others to not be killed. Others run to hunt so they can eat and live another day.