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Lumholtz’s tree kangaroos are thought to be one of the most basal members of the Dendrolagus lineage, which evolved from terrestrial macropodids. A 1985 observational study found many of their behaviors to be "primitive," i.e., less adapted to arboreal life than those of other tree kangaroos. For example, they exclusively use bipedal hopping on the ground, tend to move paired limbs together when feeding, and are reluctant to climb downwards headfirst. These behaviors are thought to be similar to those of the terrestrial ancestors of tree kangaroos.
Adults do not generally communicate with each other. However, they are capable of vocalization when agitated or disturbed. Vocalizations include a soft ‘pffft’ exhalation noise when mildly agitated and a louder ‘woof’ and moaning when more agitated. All of these noises are relatively soft, none audible from over 30 m away by a human. Hearing is not thought to be particularly well developed in D. lumholtzi, as the pinnae are smaller than those of terrestrial macropods. The relative importance of sight and smell are not well studied. It is thought, however, that males use olfactory cues to determine when females are in estrous.
Communication Channels: tactile ; acoustic
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; acoustic ; chemical
Lumholtz’s tree kangaroos are a species of least concern on the IUCN Red List and are not listed on the CITES appendices. However, relatively little of their range is protected, and habitat loss is the biggest potential threat to their well-being. Given their low birthrate and preference for small patches of isolated forest, they are quite vulnerable to habitat loss.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
There are no known adverse effects of D. lumholtzi on humans.
Lumholtz’s tree kangaroos have been hunted by indigenous Australian populations for thousands of years (Dendrolagus means “tree hare”), but the practice has essentially stopped. The species may be of slight economic importance as a source of ecotourism in Northeast Queensland.
Positive Impacts: ecotourism
As generalist arboreal folivores, Lumholtz’s tree kangaroos fill a broad ecological niche. They occur sympatrically with other arboreal folivores, Trichosaurus vulpecula johnstoni and Pseudocheirus archeri. However, direct ecological competition is avoided by food partitioning - the diet of Lumholtz’s tree kangaroos consists of leaves higher in fiber and lower in nitrogen than the preferred foods of the other folivores. The role of this species’ scat as a soil fertilizer or a seed dsiperser has not been well studied. As well as a prey species to dingoes, wild dogs, humans, and probably pythons, Lumholtz’s tree kangaroos are hosts to various parasites. They host microscopic pathogens, including the zoonotic bacterium Burkholderia pseudomallei, various species of Mycobacterium, and the coccidian Toxoplasma gondi. All of these endoparasites can be fatal. Lumholtz’s tree kangaroos are hosts to the heterodoxus louse, (Heterodoxus pygidialis), a harmless ectoparasite; and they have an endosymbiotic relationship with many species of nematode and a species of cestode (Progamotaenia dendrolagi), most of which live in the gut.
Mutualist Species:
Commensal/Parasitic Species:
Lumholtz’s tree kangaroos are generalist herbivores, feeding on the leaves of at least 37 species of plants, including trees, vines, shrubs, and epiphytes. While they most often consume adult leaves, individuals have been observed eating young leaves or flowers. Examples of species eaten include Cryptocarya triplinervis of the Lauraceae family, Alstonia scholaris of the Apocynaceae family, and Ripogonum album of the Vitaceae family. Interestingly, Lumholtz’s tree kangaroos have been observed feeding on several species of plant that are toxic to most mammals – these include weedy Lantana camara, shining stinging trees (Dendrocnide photinophylla), and wild tobacco plants (Solanum mauritianum). Lumholtz’s tree kangaroos have never been observed drinking water and there are no bodies of water within the home ranges of most individuals. They are thought to obtain enough water from moisture in and on their food. When feeding, they move the forelimbs simultaneously to grab leaves, bring them closer to the mouth, and then chew. Digestion includes foregut fermentation. Although foliage is abundant in the canopy, Lumholtz’s tree kangaroos cannot feed on all types of leaves; it is therefore not known whether food is a limiting resource.
Plant Foods: leaves; flowers
Primary Diet: herbivore (Folivore )
Lumholtz’s tree kangaroos, Dendrolagus lumholtzi, inhabit an area of approximately 5,500 sq. km in Northeast Queensland, Australia. Their range extends from the Daintree River (northern limit) to the southern end of Cardwell Range (southern limit), west to the rainforest/wet sclerophyll forest interface, and east to the coast. Their greatest concentration is in the fragmented forests of the Atherton tablelands. While possibly occurring sympatrically with Bennett’s tree kangaroos in the Mt. Carbine Tableland, the two species are generally considered allopatric. Dendrolagus lumholtzi is often found in remnant and secondary rainforests on basalt soils. It is a non-migratory species, and is only found in its native range. An estimated 12% of its distribution is within national parks; there is also considerable overlap with a World Heritage Area.
Biogeographic Regions: australian (Native )
Dendrolagus lumholtzi inhabits upland rainforest and is generally restricted to higher elevations – approximately 600 to 1200 meters above sea level. It occurs at very low densities in lowland forests. Within its optimal altitudinal range, it prefers to reside in basalt soil rainforest, with densities twice as high on basaltic soil as on acid igneous or metamorphic rock substrate (possibly due to basalt soil’s higher nutrient content). It may inhabit secondary and remnant forest patches as small as 20 hectares. Preferred habitats include microphyll vine forest, notophyll vine forest (both complex and simple), sclerophyll communities, and cleared land. Dendrolagus lumholtzi is often found in edge forest communities. It is unclear if this is where it spends the majority of its time, or if this is just where it is most easily spotted by humans. It is hypothesized that D. lumholtzi may prefer drier edge communities because too much rain leeches nutrients from the soil.
Range elevation: 600 to 1200 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest
There is little information about the lifespan of D. lumholtzi, but D. matschiei, a closely related tree kangaroo, has been reported to live for up to 20 years in captivity.
Dendrolagus lumholtzi is a small macropodid, with males averaging 8.6 kg and females averaging 7.1 kg. Adults have an average head and body length of 0.5 m, and an average tail length of 0.7 m. The hindlimbs are well developed but proportionally smaller than those of terrestrial kangaroos. The tail and forelimbs, on the other hand, are proportionally larger than those of terrestrial kangaroos. These are adaptations for arboreal locomotion. The tail is hairy, uniformly thick, non-prehensile, and may be up to 15% longer than the combined head-body length. The arms are well-developed and muscular. Ears are short and ursine. Long, curved claws are present on all five digits of the forepaws. The hind paws include a large fourth digit and medium fifth digit; the first and second digits are syndactylous, but with 2 claws. No hallux is present. Both the fore and hind paws have large, fleshy pads with numerous tuberculations (papillae), used for gripping arboreal surfaces. The entire body is covered in hair: back hair is grizzled gray with blackish tips and the underbelly is creamy or sometimes orange. The muzzle is black and there is a distinctive pale gray forehead band. The forepaws, hindpaws, and tip of the tail are also black. The adult tail is bicolored: the lower surface is black, and the upper surface is gray (same color as the back). Juveniles have an all-black tail and lack the pale forehead band. There is no evidence of significant sexual dimorphism, seasonal variation, geographic variation, or subspecies. Dendrolagus lumholtzi has long, blade-like upper premolars, similar to that of Dendrolagus inustus; this is thought to be ancestral among tree kangaroos. While the basal metabolic rate is not known precisely, it is thought to be low for a mammal of its size.
Average mass: 8.6 (males), 7.1 (females) kg.
Average length: 0.5 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
The main anti-predator adaptation of Lumholtz’s tree kangaroos is crypsis. Because they are small, solitary, nocturnal, and often high in the canopy, they are hard to find. Known predators are feral dogs (Canis lupus familiaris), dingoes (Canis lupus dingo), and humans (Homo sapiens). They are also probably eaten by amethystine pythons (Morelia amethistina), which are known predators of Bennett’s tree kangaroos. It is possible that juveniles are hunted by wedge-tailed eagles (Aquila audax).
Known Predators:
Anti-predator Adaptations: cryptic
Dendrologous lumholtzi exhibits a promiscuous, non-seasonal mating system, in which a male and a female likely form a brief consort relationship. The consort will stay together for a maximum of several days, during which copulation may occur up to three times a day. It is thought that a male will patrol his home range, approaching females whose ranges overlap with his. He will use olfactory and behavioral cues to determine whether a female is in estrous. Before copulation, a male will repeatedly sniff the female’s cloaca and pouch, probably to detect pheromones indicative of estrous. The male will then position himself behind the female, rub his head, neck, and shoulders against the cloaca, and proceed to mate. Copulation may last from 10 to 35 minutes. In captivity, copulation occurs most frequently on the ground; however, it is unknown if this occurs in the wild. A copulatory plug inhibits later fertilization by the sperm of other males. Active mate guarding and competition have not been observed.
Mating System: polygynandrous (promiscuous)
Breeding is non-seasonal. The female estrous cycle is between 47 and 64 days, with an average of 56.4 days. The length of gestation is between 42 and 48 days, with an average of 44.8 days. The young uses the mother’s pouch for approximately a year after birth; a joey will begin to look outside the pouch at approximately 250 days, and will make its first foray from the pouch at approximately 300 days. The young will continue to suckle the mother for about a month or two after it has permanently left the pouch. A juvenile may remain in its mother’s home range up to 650 days after birth. A mother will usually come into estrous about two months after its young has permanently left the pouch; the average inter-birth interval is 1.4 years and 1 offspring is produced per birth. There is no evidence that females exhibit postpartum estrous or embryonic diapause. Females reach sexual maturity at approximately 2.04 years, whereas males reach sexual maturity at approximately 4.6 years.
Breeding interval: Average inter-birth interval is 1.4 years.
Breeding season: Mating occurs year-round.
Average number of offspring: 1.
Range gestation period: 42 to 48 days.
Average gestation period: 44.8 days.
Average weaning age: 13-14 months.
Average time to independence: 13-14 months.
Average age at sexual or reproductive maturity (female): 2.04 years.
Average age at sexual or reproductive maturity (male): 4.6 years.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Aside from providing sperm for fertilization, adult males put forth no parental investment. An adult female, on the other hand, invests very much in her young. A mother allows her young to stay in the pouch for about 1 year and continues to suckle for 1 or 2 months afterwards. As the young begins to leave the pouch, the mother is protective, sometimes grabbing it and encouraging it to return. Mothers invest a large amount in teaching their offspring which leaves to eat and how to maneuver safely high in the canopy. Mother-young behavioral interactions involve frequent physical contact, often initiated by the young. The young disperses from the mother’s home range by 650 days after birth.
Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); extended period of juvenile learning
