The distribution of Dendrolagus inustus includes northern and western New Guinea. It ranges from the Vogelkop and Fak Fak Peninsula to the north coast of Papua New Guinea. There are also unconfirmed reports of D. inustus in Salawati, Irian Japen, and the Waigeo Islands.

Biogeographic Regions: australian

Other Geographic Terms: island endemic

The body of D. inustus is stern-heavy with a small head and flat muzzle. Grizzled tree kangaroos bear a close resemblance to forest and plains kangaroos and are often mistaken as terrestrial mammals. They have very long hindlegs and forelegs and long hind feet in comparison to other arboreal mammals but they are relatively short compared to kangaroos. The fourth toe is usually longer than the others. They also possess powerful arms and long curved claws to help them climb and move from tree to tree. The grizzled coloration of D. inustus distinguishes them from other tree kangaroos. The coat is slate gray to chocolate brown and of medium length. The thick fur on the shoulders grows in a reverse direction and acts as a natural water shedding device. This characteristic is shared by their tree kangaroo relatives in Australia. Grizzled tree kangaroos have distinct black ears on a gray head and have toes and a tail that is usually dark. The tail is bushy and uniform in thickness, but often hairless at the base. The tail is often used as a balancing organ, bracing the animal when climbing, although it is not prehensile. It has been recorded at an average length of 75-90 cm. The inside surface of the ears are also hairless. Grizzled tree kangaroos are sexually dimorphic, the males being much larger than the females.

Range mass: 8 to 15 kg.

Range length: 80 to 90 cm.

Sexual Dimorphism: male larger

• Terrestrial

Grizzled tree kangaroos inhabit a broad spectrum of habitats. Most records are from primary forests.

Range elevation: 100 to 1400 m.

Habitat Regions: tropical

Terrestrial Biomes: rainforest

The main food sources in the wild for D. inustus are leaves, fruit, and soft bark. Grizzled tree kangaroos in captivity do not eat animal protein such as chicken, but they do eat mealworms and boiled eggs. In zoos, they are fed carrots, bananas, etc.

Plant Foods: leaves; wood, bark, or stems; fruit

There is little information of how D. inustus play a roles in the ecosystem. As herbivores, they may limit plant populations.

The predators of D. inustus are unknown.

There is not much known about how D. inustus communicates with others or perceives the environment. Presumably, it relies on visual and tactile cues to aid its arboreal lifestyle.

Communication Channels: visual

Perception Channels: visual ; acoustic

The lifespan of D. inustus is up to 10 years.

Typical lifespan

Status: wild: 10 (high) years.

There is not much known about the mating systems of D. inustus but their relative in Australia, Dendrolagus lumholtzi, is known to be polygynous. A male investigates a receptive female by standing in front of her, making soft clucking sounds, and pawing gently at her head and shoulders. When the female moves away, the male follows and paws at the base of her tail. Also in the other tree kangaroo species of Australia, Dendrolagus bennettianus, males are very territorial with other males but their territory often overlaps with several females, leading to the idea that they are polygynous. Captive specimens have shown that in the presence of a female, two males fight competitively, but without the female they live in peace.

It is believed that the breeding of D. inustus is non-seasonal. Also, the females give birth soon after a young leaves the pouch, and before the older young becomes independent. The number of offspring is usually one, but on extremely rare cases, twins occur. Sexual maturity is reached at 8.5 to 10.6 kg in weight for females and 12 kg for males. Males continue to grow throughout their lifetime, growing to weights of 17 kg. The females of D. bennettianus breed annually and the pouch life is around 9 months. The young is known to live with the mother up to 2 years.

Breeding season: This species breeds year-round.

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Average weaning age: 8-9 months.

Range time to independence: 2 (high) years.

Average age at sexual or reproductive maturity (female): 2 years.

Average age at sexual or reproductive maturity (male): 2 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; embryonic diapause

Average number of offspring: 1.

Average age at sexual or reproductive maturity (female)

Sex: female: 510 days.

Not much is known about the parental investment of D. inustus. Like all kangaroos, females protect and nurse their young while they develop in the pouch. Female D. inustus will protect their offsrping for up to two years.

Parental Investment: altricial ; pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female)

Grizzled tree kangaroos are commonly kept as pets. They are also hunted intensively, often killed before reaching maximum size. They are also over exploited due to growing human population.

CITES: appendix ii

IUCN Red List of Threatened Species: vulnerable

There is little information pertaining negative effects on humans.

It is known that D. inustus are important as game for hunters; possibly for food but most likely for the pet trade. Grizzled tree kangaroos are also used in science for research. There is one case studied where a female grizzled tree kangaroo died from systemic arterial calcinosis, a disease resembling arteriosclerosis of the Monckeberg type in man. There is little information describing cardiovascular disorders in marsupials, therefore this case is of special interest.

Positive Impacts: pet trade ; food ; research and education