Up to 10 species of tree-kangaroo have been identified in New Guinea and Australia. Two of those species, Lumholtz’s tree-kangaroo, Dendrolagus lumholtzi, and Bennett’s tree-kangaroo, Dendrolagus bennettianus, occur only in Australia. Lumholtz’s tree-kangaroo is the smaller of the two species and can be distinguished from Bennett’s tree-kangaroo by its distribution, smaller size and by the lighter-coloured band across the forehead and down each side of the face.
Male Lumholtz’s tree-kangaroos weigh an average 7.6 kg (5.4 – 9.9 kg) and females 6.3 kg (5.1– 7.8 kg). The head and body length of males averages 520-710 mm and tail length averages 655-800 mm. Females are smaller in all dimensions (head-body length 420-675 mm; tail length 470-740 mm). The forearms of Lumholtz’s tree-kangaroos are long and heavily muscled, and the hindfeet are short and broad. Both these features differ from the normal kangaroo pattern and are adaptations for a life in the trees. The under-surface of the hindfeet is fused into a soft pad that can mould itself around branches and tree trunks to help in climbing. The front feet also have curved claws and rough, bumpy pads on the underside for gripping when climbing.
Relative to body size, the tail of Lumholtz’s tree-kangaroo (and of the other tree-kangaroo species) is the longest in the kangaroo family. It is non-prehensile (cannot be used to grip branches) and is used for balance when the tree-kangaroo is resting or moving along a branch. The fur of Lumholtz’s tree-kangaroo is blackish-brown sprinkled with a lighter colour on the lower part of the back and blackish-brown on the lower half of the tail.
Habitat and Range
Lumholtz’s tree-kangaroos are found in the rainforest of tropical Queensland, centred on the Atherton Tablelands, extending north as far as the Carbine Tableland, where the distribution of the Bennett’s tree-kangaroo begins. The original preferred habitat of the Lumholtz’s tree-kangaroo was coastal lowland rainforest. However it is now more common at higher altitudes above 300 m due to clearing of lowland habitat.
The Lumholtz’s tree-kangaroo is primarily a folivore (i.e. leaf-eater). It also feeds on many fruits and has been known to take cultivated maize from farms adjacent to its rainforest habitat.
Lumholtz’s tree-kangaroos do not appear to have a definite breeding season. Sexual maturity occurs in males at about 4.5 years of age, and in females as early as 2 years. Males “court” females by uttering a soft clucking sound and softly pawing her head and shoulders. When the female moves away the male follows, pawing at the base of her tail. Following mating there is a gestation period of 42–48 days which is the longest known gestation of any marsupial. The female gives birth to a single joey which attaches to a teat in the pouch (the teat becomes enlarged prior to birth).
Tree-kangaroos are nocturnal and they spend the daylight hours sleeping hunched over in a sitting position high in tree canopies. Living in high rainfall areas, tree-kangaroos need to be able to stay dry. To do this, the fur covering their bodies is arranged so that it points outward from a point near the middle of the back, allowing water to run off the fur while they are sleeping.
They climb trees by gripping the trunk or branch with the forelimbs and then pushing up with the hindlimbs (moving in reverse, tail-firs, when descending). Nearing the ground, a tree-kangaroo will release its hold on the trunk and kick off with its hindlegs and land on the rainforest floor and hop away. On broad horizontal branches and on the ground they may use a hopping gait or walk. Tree-kangaroos are the only group of macropods that can move their hindlimbs independently. When disturbed, they can jump to another tree or jump to the ground from a height of up to 15 m. Generally, Lumholtz’s tree-kangaroos are solitary animals and males will be aggressive toward others entering their territory. However, in captivity males are usually tolerant of females. They are a sedentary species with small home ranges of around 0.7 ha for females and 2 ha for males, and may stay within their home range even after a large disturbance, such as tree felling, rather than retreating to nearby intact forest.
The main threat to Lumholtz’s tree kangaroos is clearing of their rainforest habitat, but this has lessened with the declaration of the Wet Tropics World Heritage Area. The species appears to be able to persist in fragmented habitat and may use habitat corridors. It is possible that their unwillingness to move from their established home ranges may place them at risk where even small levels of clearing occur. This may also reduce the likelihood of successful relocation. There is an unknown virus or disease that has been known to create blindness in some individuals.
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Text © Queensland Goverment (Dept of Environment and Heritage Protection)
Image © Jona Photography