The common wombat, "Vombatus ursinus", is one of three wombat species living in Australia. It is found the mountains and hills of southeast Australia, Tasmania, and Flinders Island in Bass Strait. They look like a small bear, which is what the name "ursinus" means. It is a marsupial, a type of mammal that carried its young in a pouch. It is the largest burrowing plant-eating mammal in the world. Its closest living relative is the koala.
They are a short and muscular animal that walks on four strong legs. The feet and claws are designed to help the wombat dig tunnels in rocky ground. They are between 70–120 cm in length and weigh between 15–35 kg. It is covered in a very rough and coarse fur which can be anywhere from black to silver grey, from dark brown to sandy brown. Wombats have very tough skin on their rump.
Wombats live alone but meet up to breed in April to June on mainland Australia. In Tasmania the breeding can occur at any time of the year. The young wombats are tiny, about two cm long, when they are born after a gestation of only 21 days, and move into the mother's pouch. Wombats normally only have one baby although the pouch has two nipples. Unlike a kangaroo, the pouch opens backwards, which would prevent it from filling with dirt as it crawls into its burrow. The young wombat lives in the pouch for about six months, and finally becomes independent of the mother at about 18 months of age. Wombats live for about five years, although some in captivity have lived for 26 years.
Wombats live in burrows that they dig with their sharp claws. They are nocturnal animals, and come out their burrows in the evening to look for food. It is a herbivore, so it only eats grass, tree and shrub roots, bark, leaves, and fungi. Wombat faeces are cube shaped. The wombat will use them to mark things in its territory, so it is common to find the cubes on top of leaves, rocks, and branches. Because of their shape they do not roll off.
The burrows can be as small as two metres or as long as 30 metres. They dig with their front feet, kick the soil backwards with their back feet, and then use their rump like a bulldozer to push the dirt out of the burrow. Only one wombat lives in each burrow, but wombats may have up to four burrows in the area they live.
Farmers see the Common Wombat as a pest. It often destroys fences by burrowing, and the burrow openings are a danger to grazing animals. It is still common in Australia, but the areas it lives in are being reduced because of land clearing for farms.
The common wombat has no natural predators. It is not scared of people and is often seen in camping areas. They can make good pets.
Chimpanzee
The common chimpanzee ("Pan troglodytes"), or robust chimpanzee, is a species of great ape. The common chimpanzee is often called the chimpanzee (or "chimp"), though this can be used to refer to both species in the genus "Pan": the common chimpanzee and the closely related bonobo. Evidence from fossils and DNA sequencing show both species of chimpanzees are the closest living relatives to modern humans.
The common chimpanzee is more robust than the bonobo, weighing between and measuring approximately from head to tail. Its gestation period is eight months. The infant is weaned at about three years old, but usually maintains a close relationship with its mother for several more years; it reaches puberty at the age of eight to 10, and its lifespan in captivity is about 50 years.
The common chimpanzee lives in groups which range from 15 to 150 members, although individuals travel and forage in much smaller groups during the day. The species lives in a male-dominated, strict hierarchy, so disputes can generally be settled without the need for violence. Nearly all chimpanzee populations have been recorded using tools, modifying sticks, rocks, grass, and leaves and use them for acquiring honey, termites, ants, nuts, and water. The species has also been found creating sharpened sticks to spear Senegal bushbabies out of small holes in trees.
The common chimpanzee is listed on the IUCN Red List as an endangered species. Between 170,000 and 300,000 individuals are estimated across its range in the forests and savannahs of West and Central Africa. The biggest threats to the common chimpanzee are habitat destruction, poaching and disease.
Jane Goodall discovered that chimps hunt and eat smaller primates such as "Colobus" monkeys. Goodall watched a hunting group isolate a colobus high in a tree, block all possible exits, then one chimpanzee climbed up and captured and killed the colobus. The others then each took parts of the carcass, sharing with other members of the troop in response to begging behaviours. The chimps at Gombe kill and eat as much as "one-third of the colobus population" in the park each year. This alone was a major scientific find which challenged previous conceptions of chimp diet and behavior.
Also startling, and disturbing, was the tendency for aggression and violence "within" chimpanzee troops. Goodall observed dominant females deliberately killing the young of other females in the troop in order to maintain their dominance, sometimes going as far as cannibalism.
She says of this revelation, "During the first ten years of the study I had believed […] that the Gombe chimpanzees were, for the most part, rather nicer than human beings. […] Then suddenly we found that chimpanzees could be brutal—that they, like us, had a darker side to their nature". These findings revolutionized our knowledge of chimpanzee behaviour. They were further evidence of the social similarities between humans and chimpanzees, albeit in a much darker manner.
If they can, male chimpanzees try to kill the male members of neighbouring groups. Males work together when they spot a chance to make a lightning raid on an isolated male from the other group. They kill him. In Gombe, Tanzania, a group in the 1970s was seen to kill seven of their neighbours one by one, until all were gone. It can take years for this to happen but, when it does, the remaining females and the neighbouring territory are added to the now larger group. Attacks like this are carefully planned, done only when success is likely, and carried out in silence. Their behaviour is quite different from any other behaviour known in chimpanzees:
The advantage for the males that triumph is to breed more children. Their tribe also holds a larger territory, and so has access to more food. Several authors have drawn a connection between this behaviour and the origins of human warfare.
Bonobo
The bonobo ("Pan paniscus") is a great ape and the smaller of the two species making up the genus "Pan" (the other is "Pan troglodytes", the common chimpanzee). The bonobo is sometimes called the dwarf or pygmy chimpanzee. Although the name "chimpanzee" is sometimes used to refer to both species together, it is usually understood to mean the common chimpanzee, while "Pan paniscus" is usually referred to as the bonobo.
The bonobo lives in rain forest, in a area south of the Congo River. This is in the Democratic Republic of the Congo, Central Africa.
The bonobo has high levels of sexual behavior. Sex functions in conflict appeasement, affection, social status, excitement, and stress reduction. It occurs in virtually all partner combinations and in a variety of positions. This may explain the lower levels of aggression in the bonobo as compared to the common chimpanzee and other apes. Bonobos are matriarchal and a male's rank in the social hierarchy is often determined by his mother's rank.