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© (from left to right) Brent Stirton/Getty Images / WWF-UK . © WWF / Ian CRAVEN . © WWF / Martin HARVEY

New Guinea mammals

from left to right: Tree kangaroo / Round-eared tube-nosed bat (Murina cyclotis) Arfak Mountains, Irian Jaya, Indonesia / Short-beaked echidna (Tachyglossus aculeatus), an egg-laying mammal.

New Guinea’s mammal diversity

New Guinea has only slightly fewer mammal species than Australia, although the surface area of the former is approximately only 10% that of Australia. Mammals here include monotremes (mammals that lay eggs, instead of giving birth to live young like marsupials and placental mammals)1 , marsupials, which are native to Australia-New Guinea, bats and rodents.

Only 3 species of monotremes exist today, including the short-beaked echidna or spiny anteater (Tachyglossus aculeatus), shared by Australia and New Guinea, and the long-beaked echidna (Zaglossus bruijni), which only occurs in New Guinea at high elevations.2

Seventy-five bat species belonging to 6 families are known. Rodents, belonging exclusively to the family Muridae (rats and mice), have radiated extensively in the New Guinea region. 3

The forests of New Guinea are home to approximately 40 mammal species,  including Doria's and Goodfellow's tree kangaroos (Dendrolagus dorianus notatus and D. goodfellowi) and the Papuan forest wallaby (Dorcopsis macleayi), which are not found anywhere else.

Close mammal relatives from Australia

To understand New Guinea’s unique mammal wildlife, we need to take a closer look at rocks – more specifically, continental movement.

As the Australia-New Guinea tectonic plate ebbed to the north over millions of years, a group of mammals called marsupials evolved. When this plate collided with the Eurasian plate about 25 million years ago, New Guinea pushed up from under the seas and it was colonized by Australian marsupials.

Much later, a rise in sea level separated New Guinea from Australia and allowed mammal migrants from the south to evolve independently.

During the Ice Age, sea levels dropped again and a land connection was re-established to Australia. While some mammals crossed this divide, the unfavourable ecological conditions in this intermediate zone prevented most from doing so. 4

The now extinct giant wallabies and the diprotodon family (the largest known marsupial at more than 2.5 tonnes)5 once roamed New Guinea. Over time however, the Forests of New Guinea have favoured smaller animals, explaining why the region now hosts few large and vulnerable species. 6

A closer look at the…

What goes boing-boing in the trees?

All 6 species of tree kangaroos in Papua New Guinea (PNG) are endemic to the island of New Guinea. Three species occur in very small geographic ranges within PNG (Matschie's, Lowland and Scott's tree kangaroos) while 3 other species (Doria's, Grizzled and Goodfellow's) have somewhat larger distributions including Papua Province, Indonesia. Tree kangaroo population declines and habitat loss have accelerated in the last 3 decades.7

1 Wikipedia. Monotremes. Retrieved Feb 06 2006.
2 Muller K. 2004. The Biodiversity in New Guinea. Unpublished document.
3 Miller S. (Ed). 1994. Status of biodiversity in Papua New Guinea: Papua New Guinea Country Report on Biological Diversity. Waigani: The Department of Environment and Conservation, Conservation Resource Centre and the Africa Centre for Resources and Environment (ACRE); 67-95.
4 Muller K. 2004. The Biodiversity in New Guinea. Unpublished document.
5  Wroe S., Crowther M., Dortch J., Chong J. 2003. The size of the largest marsupial and why it matters.  Proc. R. Soc. Lond. B (Suppl.)
6 Flannery T. 1994. The Future Eaters. Reed New Holland. 432 pp.
7 Unknown. Undated. Tree Kangaroos of Papua New Guinea - Population and Habitat Viability Assessment. Lae, Papua New Guinea.  31 August – 4 September 1998.