Northern Australia’s vanishing mammals

Northern Australia’s vanishing mammals

Hot Topics in Ecology

Northern Australia’s vanishing mammals

Synthesis by Brett Murphy and John Woinarski, Charles Darwin University
The northern brushtail possum (Trichosurus vulpecula arnhemensis) has declined markedly in the savannas. Photo: Eric Vanderduys

The decline of small to medium-sized (35-5500 g) non-flying mammals in northern Australia is one of our most urgent conservation issues. In Kakadu National Park, the site with the most substantial long-term evidence base, populations of many species have collapsed since the 1970s. This pattern has repeated across the north, and only a few high-rainfall regions retain a largely-intact assemblage of mammals.

The threats are uncertain, although there is evidence that feral cats (present in the region since the 19th Century) and altered fire regimes play key roles. Cats may act synergistically with high-intensity fires, which remove ground-level vegetation cover, increasing mammals’ exposure to predation. Recent work shows cats: (1) can rapidly extirpate native rodents in experimental trials; (2) prefer habitats burnt by high-intensity fires, where they hunt more efficiently. There is evidence that frequencies of high-intensity fires increased with the loss of customary Indigenous fire management. Cattle may have similar impacts to fire, removing groundcover and facilitating predation. Other potential drivers, which have received little attention, include: (1) disease; (2) fire-driven reductions in habitat quality (e.g. reduced understorey diversity, abundance of hollow trees and logs).

Research to resolve the threats is key to formulating an effective management response. However, high rates of decline demand immediate attempts to sustain remnant populations. Management trials could focus on: (1) intensive fire management (to maintain long-unburnt habitat, prevent high-intensity fires); (2) cat suppression; (3) improving habitat quality (e.g. removing cattle, providing nest boxes). Many northern islands have retained mammal species that have declined drastically on the mainland, and also offer potential translocation sites. Biosecurity for these islands is critical, and, if cats are present, eradication should be considered.

Hot Topic Lead Author: 
Name: Brett Murphy
Email: brett.p.murphy@cdu.edu.au
Phone: 0466623079

ID Title Location Type
7571 Braithwaite R. W. & Muller W. J. (1997) Rainfall, groundwater and refuges: predicting extinctions of Australian tropical mammal species. Aust. J. Ecol. 22, 57-67. Mammal data from Kapalga, in Kakadu National Park; groundwater and rainfall data from the northern NT. Correlational
7572 Firth R. S. C., Brook B. W., Woinarski J. C. Z. & Fordham D. A. (2010) Decline and likely extinction of a northern Australian native rodent, the Brush-tailed Rabbit-rat Conilurus penicillatus. Biol. Conserv. 143, 1193-201. Cobourg Peninsula, Northern Territory (inside Garig Gunak Barlu National Park) Simulation (population viability analysis)
7573 Fisher D. O., Johnson C. N., Lawes M. J., Fritz S. A., McCallum H., Blomberg S. P., VanDerWal J., Abbott B., Frank A., Legge S., Letnic M., Thomas C. R., Fisher A., Gordon I. J. & Kutt A. (2014) The current decline of tropical marsupials in Australia: is Australian mainland and Tasmania Pre-existing contrasts
7574 Frank A. S. K., Johnson C. N., Potts J. M., Fisher A., Lawes M. J., Woinarski J. C. Z., Tuft K., Radford I. J., Gordon I. J., Collis M.-A. & Legge S. (2014) Experimental evidence that feral cats cause local extirpation of small mammals in Australia's trop Wongalara Wildlife Sanctuary, Northern Territory manipulative experiment
7575 Lawes M. J., Murphy B. P., Fisher A., Woinarski J. C. Z., Edwards A. C. & Russell-Smith J. (in press) Small mammals decline with increasing fire extent in northern Australia: evidence from long-term monitoring in Kakadu National Park. Int. J. Wildland Fir Kakadu National Park Pre-existing contrasts
7576 Legge S., Kennedy M. S., Lloyd R. A. Y., Murphy S. A. & Fisher A. (2011) Rapid recovery of mammal fauna in the central Kimberley, northern Australia, following the removal of introduced herbivores. Austral Ecol. 36, 791-9. Mornington Wildlife Sanctuary in the central Kimberley, northwestern Australia Manipulative experiment
7577 McGregor H. W., Legge S., Jones M. H. & Johnson C. N. (2014) Landscape management of fire and grazing regimes alters the fine-scale habitat utilisation by feral cats. PLoS ONE 9. Mornington Wildlife Sanctuary in the central Kimberley, northwestern Australia Pre-existing contrasts
7578 McKenzie N. L., Burbidge A. A., Baynes A., Brereton R. N., Dickman C. R., Gordon G., Gibson L. A., Menkhorst P. W., Robinson A. C., Williams M. R. & Woinarski J. C. Z. (2007) Analysis of factors implicated in the recent decline of Australia's mammal fauna Australian mainland Pre-existing gradient
7579 Murphy B. P. & Davies H. F. (2014) There is a critical weight range for Australia's declining tropical mammals. Glob. Ecol. Biogeogr. 23, 1058-61. Australian mainland and Tasmania Pre-existing gradient
7580 Oakwood M. (2000) Reproduction and demography of the northern quoll, Dasyurus hallucatus, in the lowland savanna of northern Australia. Aust. J. Zool. 48, 519-39. Kakadu National Park, Northern Territory correlational with no pre-determined gradient or contrast
7581 Price O. F., Rankmore B., Milne D., Brock C., Tynan C., Kean L. & Roeger L. (2005) Regional patterns of mammal abundance and their relationship to landscape variables in eucalypt woodlands near Darwin, northern Australia. Wildl. Res. 32, 435-46. Darwin region, Northern Territory Pre-existing gradient
7582 Woinarski J. C. Z., Armstrong M., Brennan K., Fisher A., Griffiths A. D., Hill B., Milne D. J., Palmer C., Ward S., Watson M., Winderlich S. & Young S. (2010) Monitoring indicates rapid and severe decline of native small mammals in Kakadu National Park, n Kakadu National Park, Northern Territory Time series, and pre-existing gradient
7583 Woinarski J. C. Z., Burbidge A. A. & Harrison P. L. (in press) Ongoing unraveling of a continental fauna: Decline and extinction of Australian mammals since European settlement. Proceedings of the National Academy of Sciences of the United States of Ameri Australia Review paper
7584 Woinarski J. C. Z., Legge S., Fitzsimons J. A., Traill B. J., Burbidge A. A., Fisher A., Firth R. S. C., Gordon I. J., Griffiths A. D., Johnson C. N., McKenzie N. L., Palmer C., Radford I., Rankmore B., Ritchie E. G., Ward S. & Ziembicki M. (2011) The dis Kakadu National Park, Northern Territory, plus northern Australia more broadly Review paper
7585 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 Ecol. 26, 360-70. Kapalga, in Kakadu National Park Time series
7586 Ziembicki M. R., Woinarski J. C. Z. & Mackey B. (2013) Evaluating the status of species using Indigenous knowledge: novel evidence for major native mammal declines in northern Australia. Biol. Conserv. 157, 78-92. northern half of the Northern Territory Time series, using Indigenous knowledge of mammal occurrence
7587 Ziembicki M. R., Woinarski J. C. Z., Webb J. K., Vanderduys E., Tuft K., Smith J. G., Ritchie E. G., Reardon T. B., Radford I. J., Preece N., Perry J., Murphy B. P., McGregor H., Legge S., Leahy L., Lawes M. J., Kanowski J., Johnson C. N., James A., Griff northern Australia Review paper