Kangaroos are marsupials and belong to the Family Macropodidae (i.e. big feet) that is grouped with the Potoroidae (potoroos, bettongs, rat-kangaroos) and Hypsiprymnodontidae (musky rat-kangaroo) in the Super-Family, Macropodoidea. This comprises around 50 species in
The species commonly called the ‘kangaroos’ are the result of an arbitrary division of the Macropodidae based on a hind foot longer than 250 mm. The kangaroos then comprise six species of which the best known are the Red Kangaroo (Macropus rufus) of the arid heartland and the Eastern Grey Kangaroo (M. giganteus), the latter being Skippy's species. The Eastern Grey Kangaroo has a broad latitudinal distribution up the eastern part of Australia from northern Tasmania to Cape York. Its close relative, the Western Grey Kangaroo (M. fuliginosus) has a southerly and westerly distribution form western NSW and Victoria through South Australia to Western Australia. The Common Wallaroo has the broadest geographic distribuion of the kangaroos and forms a cline of subspecies across the continent but wallaroos are not found in Tasmania. The remaining two kangaroo species are less well-known and include the Antilopine Wallaroo (M. antilopinus) from the
Tasmanian Eastern Grey Kangaroo
Macropus giganteus tasmaniensis ('Tasmanian giant long-foot')
Mount William National Park, Tasmania
Mt William National Park is in the north-east of Tasmania and includes long stretches of white beach amongst its attractions. Amongst the coastal heaths and woodlands are abundant wildlife of which the Eastern Grey Kangaroo (known locally as the Forester kangaroo) is the largest (terrestrial) representative. Other mammals like Bennett's Wallabies, Tasmanian pademelons, Common Wombats, Echidnas and Tasmanian Devils are common. The Park is about 2 hours drive from Launceston via the town of Gladstone. Launceston has air and ferry services from mainland Australia.
Eastern Grey Kangaroos hop with the back at a higher angle to the horizontal than Red Kangaroos and the forelimbs more extended. The curve and swing of the tail is also more pronounced.
Eastern Grey Kangaroo is a woodland, forest edge species grazing out from these havens of dense shelter at night onto short green pastures. The Eastern Grey Kangaroo is probably the most opportunistic and adaptable of all the large kangaroo species. Its range spans latitudes from northern
Eastern Grey Kangaroos are primarily grass eaters and so potentially compete with other macropods in their habitat. Microhabitat differences tying the Eastern Greys to dense lateral cover for daytime shelter keep the species somewhat apart. However, the large gut provides an efficient fermentative chamber allowing the Eastern Grey Kangaroo to digest poorer quality food than smaller macropods which need to select small parcels of high quality vegetation like growing tips of plants rather than swards of grasses.
Eastern Grey Kangaroos prefer short green pasture and and their grazing
will contribute to creating grazing lawns which are diverse in species
composition and compact creating a strong ground cover. The creation of urban
parks and golf courses with clumps of trees and permanent water provides ideal
Eastern Grey Kangaroo habitat. Thus they are common in the peri-urban
environment and may seen on many country golf fairways.
Eastern Grey Kangaroos prefer short green pasture and and their grazing will contribute to creating grazing lawns which are diverse in species composition and compact creating a strong ground cover. The creation of urban parks and golf courses with clumps of trees and permanent water provides ideal Eastern Grey Kangaroo habitat. Thus they are common in the peri-urban environment and may seen on many country golf fairways.
The reproductive biology of the Grey Kangaroos sets them apart from the Red Kangaroos and Euros. Development of the offspring is much slower so that young of comparable size permanently exit the pouch at around 320 days compared to 235 in Red Kangaroos and are weaned at 540 days compared to 360 in Red Kangaroos. Breeding is more seasonable with a broad peak in births from October through to March, although this may be more variable in the arid zone.
Eastern Grey Kangaroos do not mate immediately after birth since the oestrous cycle is around 10 days longer than length of pregnancy. They may also mate while they have a young in the pouch, which is about six months old. The resulting embryo remains quiescent (in diapause) due to inhibition of further development while the female is lactating. It is born when the pouch young permanently exits or dies prematurely.
In temperate habitat, a single alpha male has exclusive dominion over a mob of females that may number 30-40 or more. His tenure is typically a single year and competition for the top rank is especially fierce. Females often aggregate with their female relatives so that a group of daughters, mothers, grandmothers and so on may form. This seems to provide greater reproductive success in the younger females but there may be a limit to how large these matrilineal groups can grow as females may produce dispersing sons later in life and stay-at-home daughters earlier on.
The mating system in the arid zone is less well known as groups are smaller, commensurate with the small populations. However, you see very few very large males and so we suspect that these hold dominion but perhaps for more than a single year. Females remain quite faithful to their home range and only extreme drought may cause them to move temporarily so matrilineal groups probably build up over time.
FEastern Grey Kangaroo mothers spend a relatively long period with their young and so offer a good opportunity to observe the affectionate and endearing bond between a mother and her joey. Look out for smaller females nearby, as these may be her daughters.
Eastern Grey Kangaroos are the most social of the kangaroos and so it is rare to see one alone. If you do it is likely to be a male in transit to check out the reproductive status of females in some other part of the mob or a mother with her young-at-foot. One good reason to gather together in a group is that more individuals can be more attentive to possible threats from predators. The chance that someone is looking out when the predator makes its attack increases with group size. Likewise when the group flees, the distraction of many individuals following interweaving paths is greater than a single target fleeing alone. It thus seems odd that mothers with their vulnerable young wander off alone from the mob. The explanation seems to be that the mob is a confusing place for a young-at-foot when potential 'mothers' flee in many directions. Thus mothers remove there immature young-at-foot and train them to retrieve the pouch, if not past permanent exit, or follow closely before again associating with their fellows.
Dawson, T.J. (1995). Kangaroos: biology of the largest marsupials. (UNSW Press: Sydney)
Coulson G (1997) Repertoires of social behaviour in captive and free-ranging grey kangaroos, Macropus giganteus and Macropus fuliginosus (Marsupialia: Macropodidae). Journal of Zoology (London) 242, 119-130.