Tree-kangaroos are macropods adapted for life in trees. They inhabit the rainforests of Australia and New Guinea, far northeastern Queensland, and nearby islands. Although most are found in mountainous areas, several species also occur in lowlands, such as the aptly named Lowlands Tree-kangaroo. Most tree-kangaroos are considered threatened due to hunting and habitat loss.
There are 14 species of tree-kangaroos, though some uncertainty exists due to taxonomy. Depending on species, there are significant variations in the color of the pelage and size, with a head and body length of 41 to 77 centimetres (16 to 30 in), a tail length of 40 to 87 centimetres (16 to 34 in), and a weight of up to 14.5 kilograms (32 lb). Females are smaller than males.
The evolutionary history of Tree-Kangaroos begins with a rainforest floor dwelling pademelon-like ancestor (Thylogale spp.). This ancestor evolved from an arboreal possum-like ancestor as is suspected of all Macropodid marsupials in Australia and New Guinea. During the late Eocene the Australian/New Guinean continent began a period of drying that caused a retreat in the area of rainforest. The retreat of the rainforest forced the ancestral Pademelons to begin living in a dryer, rockier environment. After some generations of adaptation to the new environment, the Pademelons (Thylogale spp.) evolved into Rock-wallabies (Petrogale spp.). The Rock-wallabies developed a generalist feeding strategy due to their dependence on a diverse assortment of vegetation refuges. This generalist strategy allowed the Rock-wallabies to easily adapt to malesian rainforest types that were introduced to Australia from Asia during the mid-Miocene. The Rock-wallabies that migrated into these introduced forests adapted to spend more time climbing trees. One species in particular, the Proserpine Rock-wallaby (Petrogale persephone), displays equal preference for climbing trees as for living in rocky outcrops. During the late-Miocene the semi-arboreal Rock-wallabies evolved into the now extinct tree-kangaroo genus Bohra. Global cooling during the Pleistocene caused continent wide drying and rainforest retractions in Australia and New Guinea. The rainforest contractions isolated populations of Bohra which resulted in the evolution of today's tree-kangaroos (Dendrolagus spp.) as they adapted to lifestyles in geographically small and diverse rainforest fragments, and became further specialized for a canopy dwelling lifestyle.
Tree-kangaroos are slow and clumsy on the ground. They move at about walking pace and hop awkwardly, leaning their body far forward to balance the heavy tail. But in trees they are bold and agile. They climb by wrapping the forelimbs around the back of a tree and hopping with the powerful hind legs, allowing the forelimbs to slide. They are expert leapers; 9 metres (30 ft) downward jumps from one tree to another have been recorded, and they have the extraordinary ability to jump to the ground from 18 metres (59 ft) or more without being hurt.
The following species are assigned to the genus Dendrolagus:
- Grizzled Tree-kangaroo, Dendrolagus inustus; northern and western New Guinea, plus the island of Yapen, and possibly Salawati and Waigeo.
- Lumholtz's Tree-kangaroo, Dendrolagus lumholtzi; Queensland, Australia.
- Bennett's Tree-kangaroo, Dendrolagus bennettianus; Queensland, Australia.
- Ursine Tree-kangaroo, Dendrolagus ursinus; Vogelkop, New Guinea.
- Matschie's Tree-kangaroo, Dendrolagus matschiei; Huon Peninsula, New Guinea.
- Doria's Tree-kangaroo, Dendrolagus dorianus; western, central, and southeastern New Guinea.
- Seri's Tree-kangaroo, Dendrolagus stellarum; highlands of west-central New Guinea.
- Goodfellow's Tree-kangaroo, Dendrolagus goodfellowi; central and southeastern New Guinea.
- Golden-mantled Tree-kangaroo, Dendrolagus pulcherrimus; Foja and Torricelli Mountains, New Guinea.
- Lowlands Tree-kangaroo, Dendrolagus spadix; south-western lowlands of Papua New Guinea.
- Dingiso, Dendrolagus mbaiso; highlands of west-central New Guinea
- Tenkile, Dendrolagus scottae; Sandaun Province, New Guinea.
The taxonomy, especially of the Dendrolagus dorianus and Dendrolagus goodfellowi superspecies, is complex. The taxon stellarum was described as a subspecies of the D. dorianus, but some recent authorities have treated it as a species based on its absolute diagnostability. It has further been suggested that the taxon mayri, known only from a single old specimen, may represent a valid species, but as it is virtually unknown, most authorities have retained it as a subspecies of D. dorianus. The case for pulcherrimus is comparable to that of stellarum. It was initially described as a subspecies of Dendrolagus goodfellowi, but recent authorities have elevated it to species status based on its absolute diagnostability. A population of the Tenkile recently discovered from the Bewani Mountains may represent an undescribed subspecies.
Back and tail of a Buergers' Tree-kangaroo (D. g. buergersi)
Two Goodfellow's Tree-kangaroos, Dendrolagus goodfellowi
- Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 59–61. OCLC 62265494. ISBN 0-801-88221-4.
- Martin, Roger William (July 2005). Tree-kangaroos of Australia and New Guinea. CSIRO. ISBN 978-0-643-09072-9.
- Archer, Mike (1991). Riversleigh: The Story of Animals in Ancient Rainforest of Inland Australia. Bangowlah, NSW: Reed Books.
- Tuft, K. D.; Crowther, M.S.; McArthur, C. (2011). "Multiple scales of diet selection of brush-tailed rock-wallabies (Petrogale penicillata)". Australian Mammalogy 33: 169–180.
- Flannery, Timothy; Martin, Roger; Szalay, Alexandra (1996). Tree-kangaroos: A Curious Natural History. Melbourne VIC: Reed Books. pp. 68–72. ISBN 978-0-7301-0492-6.
- Hopkins, M. S.; J. Ash, A. W. Graham, J. Head, and R. K. Hewitt (1993). "Charcoal evidence of the spatial extent of the Eucalyptus woodland expansions and rainforest contractions in North Queensland during the late Pleistocene". Journal of Biogeography 20: 357–372.
- Prideaux, G. J., Warburton, N.M. (2010). Macropods:. Collingwood, VIC: CSIRO. pp. 137–151.
- Flannery, T. (1995). Mammals of New Guinea. Reed Books. ISBN 0-7301-0411-7.
- Nowak, R., ed. (1999). Walker's Mammals of the World (6th ed.). Johns Hopkins University Press. ISBN 0-8018-5789-9.
- Wondiwoi Tree Kangaroo Tenkile Conservation Alliance
- Tenkile Tree Kangaroo Tenkile Conservation Alliance