| Australian Sea Lion | |
|---|---|
 | |
| Estimated Population | 14,730 |
| Scientific Classification | |
| Kingdom | Animalia |
| Phylum | Chordata |
| Class | Mammalia |
| Order | Carnivora |
| Family | Otariidae |
| Genus | Neophoca |
| Species | N. Cinerea |
| Conservation Status | |
 Endangered | |
The Australian sea lion (Neophoca cinerea) also known as the Australian sea-lion or Australian sealion, is a species of sea lion that is the only endemic pinniped in Australia.[2] It is currently monotypic in the genus Neophoca, with the extinct Pleistocene New Zealand sea lion Neophoca palatina the only known congener.[3] These sea lions are sparsely distributed through Houtman Arbrolhos Islands (28°S., 114°E.) in Western Australia and The Pages Islands (35°46’S., 138°18’E) in Southern Australia. With a population estimated at around 14,730 animals, the Wildlife Conservation Act of Western Australia (1950) has listed them as “in need of special protection”. Their Conservation status is listed as endangered. These pinnipeds are specifically known for their abnormal breeding cycles, which are varied between 5 months breeding cycle and a 17-18 month aseasonal breeding cycle, compared to other pinnipeds which fit into a 12-month reproductive cycle.[2]Females are either silver or fawn with a cream underbelly and males are dark chocolate brown with a yellow mane and are bigger than the females.
Behavior[]
Australian Sea lions breed on at least 50 islands, 27 in Western Australia and 23 in Southern Australia. Prior to a study that took place from 1987-1992, 31 of the 50 islands were undiscovered, as well as 19 more islands considered additional breeding grounds.[10] On the basis of surveys conducted primarily in 1990, about 70% of the population was in Southern Australia and 30% in Western-Australia.[11] Pup production was estimated at 2432 for these 50 islands in 1990. In 1994 and 1995 another 10 breeding colonies were recorded on the mainland in the Great Australian Bight region, only producing 161 pups.[11] Thus, reproduction is yielding less and less pups per breeding season. The four largest colonies, on The Pages Islands, at Seal Bay on Kangaroo Island, and at Dangerous Reef, produced 42% of the total pup numbers; they are at the eastern end of the range, east of Port Lincoln.[11]
The breeding cycle of the Australian sea lion is unusual within the pinniped family. It is a 17.6 to 18-month cycle and is 'not' synchronized between colonies. However, census data collected since 1973 shows that breeding events shift forward in time to 13.8 days earlier every 18 months.[12] The duration of the breeding season can range from five to seven months and has been recorded for up to nine months at Seal Bay on Kangaroo Island.
Bulls do not have fixed territories during the breeding season. The males fight other males from a very young age to establish their individual positions in the male hierarchy and during the breeding season, dominant males will guard females for the right to breed with her when she comes into oestrus. A female comes into season for about 24 hours within 7 to 10 days after she has given birth to her new pup. She will only look after the new pup and generally fights off the previous season's pup if it attempts to continue to suckle from her. Male Australian sea lions are also known to kill young as an act of defence of territory.
Australian sea lions also practice alloparental care, in which an adult may adopt the pup or pups of another. This might take place if the original parents die or are for some reason separated from them. This behavior is common and is seen in many other animal species such as the elephant and fathead minnow.[13]
Diet[]
The Australian Sea Lion's diet is poorly known but probably includes a variety of fish and invertebrates such as octopus and squid. There is some suggestion that they occasionally eat penguins.