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 ancestor of the kangaroos and their kind was possum-like and descended from the trees to spawn a large and diverse fauna of browsers and grazers. Curiously one group the Tree-kangaroos ascended the trees again to exploit the large foliovore (leaf-eating) niche in the tropics of Australia and Papua New Guinea (PNG) occupied by primates like Proboscis Monkeys in nearby Indonesia. Thus the Tree-kangaroos are in many respects the closest animals we have to monkeys in the Australo-Papuan region. Unfortunately for Tree-kangaroos their meat is tasty (hence the genus Dendrolagus or tree-hare given by the Dutch) and hunting along with habitat destruction and climate change are significant threats. Thus the majority of species are threatened or vulnerable under IUCN Red List classification.
The centre of diversity of the Tree-kangaroos is PNG rather than Australia. Eight species are recognised in PNG and probably more remain to be formerly described by taxonomists. The Tenkile (Dendrolagus scottae) was described by Flannery and Seri as recently as 1990. Two species are found in tropical north Queensland in Australia. The larger is Bennett's Tree-kangaroo described by De Vis in 1887 and named in honour of Dr George Bennett of the Australian Museum in Sydney. The smaller species is Lumholtz's Tree-kangaroo described by Collett in 1884 and named after Rev. Carl Lumholtz a collector sponsored by the University of Christiana in Norway.
The body form of the terrestrial kangaroos (ancestral to the Tree-Kangaroos) is a reduction in the fore-limbs and an accentuation of the hind-limbs for locomotion. The body form of Tree-kangaroos sees a more equal distribution of body mass and musculature in the fore and hind parts. The fore-arms are large and well-muscled to assist climbing and the fore-paws are strongly clawed with pronounced curvature in the claws. The fore-paw aids tree-climbing but also is used to grasp and manipulate food. The hind-limbs remained enlarged but the feet are short, very broad and have a long curved claw on each digit. The pad on both hind and fore-feet is fleshy with prominent tuberculations that aid grip when climbing. The ankle allows more degrees of movement than a terrestrial kangaroo and presumably also aids climbing. The tails of the Australian Tree-kangaroos are very long and exceed the head-body length. They appear to be used as a counterbalance and vary in placement from over the body in sedate hopping to rigidly out when rapidly fleeing. The ears are relatively reduced to small bear-like proportions in contrast to the large terrestrial kangaroos.
Dendrolagus lumholtzi ('Lumholtz's tree-hare')
Crater Lakes National Park or Curtain Fig National Park, Queensland
The Crater Lakes National Park has two sections - Lake Barrine and Lake Eacham. Both Lakes are within the Wet Tropics World Heritage area. The Lakes are fringed by rainforest where the Musky Rat-Kangaroo and Red-legged Pademelon can be seen by day. At night, Lumholtz's Tree-kangaroo may be viewed along the various walking trails at each Lake. The Park does not have accommodation or camping but is near Cairns and other locations in the Atherton Tablelands of Queensland that have a full range of accommodation. Nearby Curtain Fig National Park is also another likely place to see Lumholtz's Tree-kangaroo as it secures a remnant of mabi forest (or notophyll vine forest). Mabi is an indigenous name for the Tree-kangaroo. There is no camping in this Park but spotlighting is allowed following the advice given on the Park's website (note: a low-wattage bulb 30W or less should be used). Advice from a local wildlife tour operator (www.alanswildlifetours.com.au) is that sightings are more likely in the Curtin Fig/Yungaburra area than the Crater Lakes National Park. He nominates Petersen Creek, Yungaburra; Wongabel State Forest; and Malanda Falls Conservation Park as his 'best-place-to-see'.
The Tree-kangaroo Group (www.tree-kangaroo.net) provide the following tips for spotting Tree-kangaroos.
- They are small objects (dog sized), very hard to spot and may be high in the tree canopy. The long pendulous tail is the best cue.
- Looking up into the tree canopy is inferior to looking as horizontal as possible into it. Thus find high ground in sloping terrain and look into canopy.
- Overcast drizzling rain is a good time to spot Tree-kangaroos as they come to the edges of branches rather than remaining in dense foliage. Heavy rain causes them to shelter in dense foliage and they will be difficult to see.
- Late afternoon and early evening herald the start of the night active period and are good times to see females.
- Night spotlighting is possible with a dull ruby red eyeshine that is less intense than possums. Tree-kangaroos are skittish at night and will readily retreat from the spotlighter.
Lumholtz's Tree-kangaroo is found in north-east Queensland including the popular tourism destination, the Atherton Tablelands. The species' main habitat is upland closed forest. They are difficult to see when high up in the canopy and usually obscured by foliage.
The diet of Lumholtz's Tree-kangaroo has been well-studied by direct observation of foraging individuals in the Curtain Fig forest. They eat mainly foliage (leaves) and some flowers from about 30 species of plant including 21 tree species and 6 vine species. The majority of observations were of consumption of mature leaves. A further study analysing faecal pellets at a higher elevation site added another 6 tree species and one vine to the diet. Thus Lumholtz's Tree-kangaroo is a generalist in its diet. Several interesting observations were made of consumption of normally toxic plants and weeds like Lantana and Wild Tobacco. Given that mature leaves often have deterrents against herbivory like tannins and toxins, the broad diet of Lumholtz's Tree-kangaroo suggest a powerful gut for a relatively small herbivore.
Adult individuals of the same sex do not typically share home ranges but those of males and females overlap. Males will fight to exclude other males from their home range. Home ranges are very small with estimates of 0.3-1.5 ha for females and 1 - 3 had for males.
Breeding is aseasonal unlike Bennett's Tree-kangaroo but this observation may be an artefact of captivity where the species was studied. However, rainfall in the Lumholtz's Tree-kangaroo range is also less seasonal than the marked Wet-Dry of the more northerly Bennett's Tree-kangaroo habitat. Male sexual behaviour is typical of macropods in general with the male consorting with a female sniffing her cloaca and pouch. If the female is receptive (in oestrus) the male proceeds to rub his head, neck and shoulders on her cloaca while she elevates her hindquarters supporting her weight on her forepaws. Thus the male is coated with exudates from the cloaca which is an unusual behaviour in macropods. More typical is the male rubbing his neck and chest on the female while mounted and coating her with excretions from a sternal gland. Males mount in from the rear in the typical fashion of macropods with the female elevating her rump to assist entry. During a copulation that lasts 10-35 min, the female makes a soft trumpeting sound.
The gestation period, averaging 45 days, is exceptionally long for macropods. Oestrus is not post-partum (1-2 days after birth) and there is no evidence of embryonic diapause. Female Lumholtz's Tree-kangaroos come into oestrus about 2 months after permanent pouch exit of the current offspring following 9 months of pouch life. This is about the time the current offspring is weaned and leads to long birth intervals of about 1.4 years and relatively low fecundity.
Bennett's Tree-kangaroos will be typically seen alone but resident males and females whose home ranges overlap may associate as a pair. Females may share their home range with recent offspring after weaning and this may assist the young to adapt to its complex arboreal environment. Males are intolerant of other males and thus male home ranges are defended territories unlike most terrestrial macropods. The very small home ranges may be indicative of high habitat quality and the likelihood of rain throughout the year in the sites where they have been radio-tracked.
Johnson PM, Delean S (2003) Reproduction of Lumholtz's tree-kangaroo, Dendrolagus lumholtzi (Marsupialia: Macropodidae) in captivity with age estimation and development of the young. Wildlife Research 30, 505-512.
Martin, R (2005) Tree-kangaroos of Australia and New Guinea. (CSIRO Publishing: Melbourne).
Newell GR (1999) Home range and habitat use by Lumholtz's tree-kangaroo (Dendrolagus lumholtzi) within a rainforest fragment in north Queensland. Wildlife Research 26, 129-145.