James Cook University, Townsville

Ecology, conservation status and management of a tropical Kangaroo: The Antilopine Wallaroo (Macropus antilopinus) on Cape York Peninsula

Aims and outcomes | Tropical kangaroo | Wallaroo populations in Queensland | Intensification of cattle grazing | Property planning in Cape York | Mammal decline in northern Australia | Rapid decline in north | Supervisors | References |

The antilopine wallaroo—surveys have shown numbers are declining in Cape York

Aims and outcomes

The principal aim of this study is to determine the current population status and document the ecology of the antilopine wallaroo ( Macropu antilopinus ) within its Queensland distribution. Recent surveys and research has shown that the wallaroo may be in decline, and has been identified in this way by the Queensland Parks & Wildlife Service. The range of the species in Queensland is restricted and patchy, which means the animal could quickly become rare and threatened if observed trends continue, facilitating a need for proactive management.

This study will provide essential information on habitat requirements that will underpin the wallaroo’s management. Further, by identifying possible causes of decline, the study will produce specific recommendations on the changes in land management needed to prevent further declines. Conservation of the species will ultimately depend on appropriate management of cattle grazing properties, the dominant land use throughout its range.

Tropical kangaroo

The antilopine wallaroo ( Macropus antilopinus ) is Australia’s only kangaroo species restricted entirely to the tropics, making it both a high conservation priority and interesting study subject. The species also has the potential to assist in the sustainable use of tropical savannas through a commercial and/or indigenous harvest and ecotourism.

At present two geographically separate populations are recognized: one on the Cape York Peninsula (CYP), and the other in the Top End of the Northern Territory (Strahan, 1995). The ecology of the wallaroo is poorly known with only a few minor field studies conducted in the Northern Territory (Russell and Richardson, 1971; Croft, 1982 & Croft, 1987). No systematic, detailed research exists on the species within its Queensland range.

This project will make an intensive systematic study at a local scale and broad-scale surveys throughout Cape York Peninsula.

Wallaroo populations in Queensland

Observations in the vast wilderness area of Cape York Peninsula, has shown widespread mammal declines (Christopher Johnson, Peter Johnson & John Winter, pers. comm., 2002). The Cape is approximately 13.5 million hectares in size and encompasses a diverse assemblage of habitats and associated flora and fauna.

Mammal species recorded as declining include the black footed tree rat ( Mesembriomys gouldii ), northern quoll ( Dasyurus hallucatus ), common brushtail possum ( Trichosurus vulpecula ), rufous bettong ( Aepyprymnus rufescens ), some rock wallabies ( Petrogale spp.) and the antilopine wallaroo ( Macropus antilopinus ) (John Winter, Christopher Johnson & Peter Johnson, pers. comm., 2002).

Of the six living species of kangaroos (mean adult body weight more than 20 kg) none have been listed as endangered (Dawson, 1995) and the reported reduction in abundance of the antilopine wallaroo may represent the first observed decline of a kangaroo since European settlement.

Typically kangaroos have prospered as a result of the land-management practices associated with livestock grazing; the establishment of permanent water sources, clearing of woodland in favour of grasslands and the removal of predators, particularly dingoes.

Large reductions in the abundance of the antilopine wallaroo have been noted in the southern parts of its Queensland range, where the species was abundant in the early 1980s but is now apparently relatively scarce (Peter Johnson, pers. comm).

Intensification of cattle grazing

This reported decline occurred at the same time as an intensification of cattle grazing throughout areas of north Queensland in the 1970s and 1980s, leading to the establishment of Brahman ( Bos indicus ) breeds of cattle and the widespread provision of nutrient supplements for cattle.

The association between an intensification of cattle grazing and a reduction in M. antilopinus abundance may indicate this macropod is sensitive to habitat changes related with the introduction of livestock. This relationship contrasts with other kangaroo species (e.g. Macropus rufus, Macropus giganteus ), which have typically flourished on cattle properties.

Wallaroos drinking at a dam

Property planning in Cape York

Cooperative management of the resources of CYP, as envisaged in the Cape York Natural Heritage Trust Plan, is to be based on property planning that takes into account the goals of commercial utilisation (primarily for cattle grazing), indigenous rights and nature conservation. This study will provide the basic information needed to incorporate appropriate management of the habitat of the antilopine wallaroo into property planning on the Cape.

Given that the antilopine wallaroo is harvested as a bush food by Aboriginal communities, our estimates of population size, distribution and reproductive rates will allow us to estimate sustainable harvest rates. The study will also result in a better understanding of recent ecological changes on Cape York Peninsula, and their effects on wildlife.

Supervisors

C. Johnson, JCU
A. Krockenberger, JCU
J. Woinarski, NT DIPE

References

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Calaby, J.H. & Grigg, G.C. 1989, 'Changes in macropodid communities and populations in the past 200 years, and the future', in Grigg, G., Jarman, J. & Hume, I., editors. Kangaroos, wallabies, and rat kangaroos. Surrey Beatty and Sons, Sydney, pp. 813-820.

Cardillo, M. & Bromham, L. 2001, 'Body size and risk of extinction in Australian mammals', Conservation Biology . 15(5): 1435-1440.

Carpenter, G., Gillison, A.N. & Winter, J. 1993, 'DOMAIN: a flexible modelling procedure for mapping potential distributions of plants and animals', Biodiversity and Conservation .2: 667-680

Croft, D.B. 1982, 'Some observations on the behaviour of the Antilopine Wallaroo Macropus antilopinus (Marsupialia: Macropodidae)', Australian Mammalogy . 5: 5-13.

Croft, D.B. 1987, 'Socio-ecology of the Antilopine Wallaroo, Macropus antilopinus , in the Northern Territory, with observations on sympatric M. robustus woodwardii and M. agilis ', Australian Wildlife Research .14: 243-255.

Dawson, T.J. 1995, Kangaroos: biology of the largest marsupials , UNSW Press, Sydney.

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Johnson, K.A., Burbidge, A.A. & McKenzie, N.L. 1989, 'Australian Macropoidea: status, causes of decline, and future research and management', in Grigg, G., Jarman, J. & Hume, I., editors. Kangaroos, wallabies, and rat kangaroos. Surrey Beatty and Sons, Sydney, pp. 641-657.

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R. Strahan, (Ed.) 1995, The mammals of Australia , Reed New Holland, Sydney.

Woinarski, J.C.Z., Milne, D.J. & Wanganeen, G. 2001, 'Changes in mammal populations in relatively intact landscapes of Kakadu National Park, Northern Territory, Australia', Austral Ecology , 26:360–370.

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