Using carbon isotope analysis of the diet of two introduced Australian megaherbivores to understand Pleistocene megafaunal extinctions

Bowman, David M. J. S.; Murphy, Brett P.; McMahon, Clive R.

doi:10.1111/j.1365-2699.2009.02206.x

Cited by 23 publications

(35 citation statements)

References 37 publications

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“…This view is based on our observation that forest distribution and savanna tree cover are broadly similar between Africa and Australia (Figs 2 and 4). The large herbivore niche has been entirely empty in Australia for around 45 000 years (Bowman et al. 2010b), albeit now filled by exotic grazers such as horses, donkeys and swamp buffalo in the savannas.…”

Section: Disturbance‐based Controlsmentioning

confidence: 99%

What controls the distribution of tropical forest and savanna?

2012

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Forest and savanna biomes dominate the tropics, yet factors controlling their distribution remain poorly understood. Climate is clearly important, but extensive savannas in some high rainfall areas suggest a decoupling of climate and vegetation. In some situations edaphic factors are important, with forest often associated with high nutrient availability. Fire also plays a key role in limiting forest, with fire exclusion often causing a switch from savanna to forest. These observations can be captured by a broad conceptual model with two components: (1) forest and savanna are alternative stable states, maintained by tree cover-fire feedbacks, (2) the interaction between tree growth rates and fire frequency limits forest development; any factor that increases growth (e.g. elevated availability of water, nutrients, CO 2 ), or decreases fire frequency, will favour canopy closure. This model is consistent with the range of environmental variables correlated with forest distribution, and with the current trend of forest expansion, likely driven by increasing CO 2 concentrations. Resolving the drivers of forest and savanna distribution has moved beyond simple correlative studies that are unlikely to establish ultimate causation. Experiments using Dynamic Global Vegetation Models, parameterised with measurements from each continent, provide an important tool for understanding the controls of these systems.

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Section: Disturbance‐based Controlsmentioning

confidence: 99%

What controls the distribution of tropical forest and savanna?

2012

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“…1). Buffalo have a generalist diet, and their success in northern Australian signals they are well adapted to the region's harsh monsoonal environment (Bowman et al 2010b). We found that the current population of free-ranging swamp buffalo has high fertility rates (i.e.…”

Section: Discussionmentioning

confidence: 76%

“…In contrast, the smaller founder population (n = 20) of banteng (Bos javanicus) was introduced to Australia in the 1820s (Bradshaw et al 2007b); however, the species did not spread widely across northern Australia and, currently, between 5000 and 7000 animals (Bradshaw et al 2007b) remain close to the introduction site on the Cobourg Peninsula (Bowman et al 2010b). It has been proposed that the banteng's restricted habitat use and specialised browser diet is largely responsible for limiting the invasive capacity of the species (Bowman et al 2010b), and that this constrains population growth (Choquenot 1993) and dispersal capability (Bowman et al 2010b). There is little evidence of environmental impacts from banteng beyond browse lines on palatable trees, and trampling vegetation on trails and resting areas (Bowman and Panton 1994).…”

Section: History Of Buffalo and Banteng Introductionsmentioning

confidence: 99%

Fertility partially drives the relative success of two introduced bovines (Bubalus bubalis and Bos javanicus) in the Australian tropics

et al. 2011

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Context Some large herbivores introduced to Australia have achieved population densities so high as to cause considerable ecological damage. Intriguingly, others have been relatively less successful and have correspondingly perturbed their new environments less. An excellent example is two similar-sized bovine species that established feral populations in the Northern Territory of Australia in the mid-19th century. Asian swamp buffalo (Bubalus bubalis) rapidly colonised the tropical savannas, causing ecological degradation, especially on freshwater swamps. In contrast, banteng (Bos javanicus) are restricted to their point of introduction and have caused relatively negligible ecological damage. Understanding the reasons of this differential success is of theoretical and applied interest and contributes to managing large herbivore populations for ex situ conservation and feral-animal control. Aims To compare the population structure of buffalo and banteng on the basis of shot samples, so as to construct life tables for four contemporary (low-density) buffalo populations, and collated data from previous work from three historical (high-density) buffalo populations and one banteng population (the only extant ex situ population in existence). Further, to provide a validation of age estimation with and without informed priors in a Bayesian model comparing horn length and ages estimated from tooth cementum annuli. Finally, to interpret our results in the context of relative invasion potential of the two bovid species. Key Results For both species, survival of juveniles was the most important demographic component influencing deterministic population growth. However, buffalo have the demographic capacity to recover swiftly after control because of high survival and fertility rates across a range of population densities. Fertility of buffalo was historically greater than that of banteng, and buffalo fertility increased as their populations were reduced. Conclusions These findings highlight how subtle differences in demographic rates and feeding ecology can influence the success (high population growth and range expansion) of large herbivores, knowledge which is increasingly important for managing invasive species effectively. Implications We show that that individual life-history traits and demographic performance, especially fertility, play an important role in determining the spread of invasive bovids in a novel environment.

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“…Introduced buffalo are a potentially valuable resource that could aid rural development in disadvantaged aboriginal communities of northern Australia. The buffalo population is increasing and they are well-adapted to the monsoonal tropics (Bowman et al 2010;. Indeed buffalo are an excellent low-maintenance resource because unlike cattle, they can maintain body condition and positive growth during times of low food or quality (Ford 1978(Ford , 1982Moran 1986Moran , 1992.…”

Section: Discussionmentioning

confidence: 99%

“…At higher densities, swamp buffalo cause major environmental damage such as saltwater intrusion into sensitive wetlands through the trampling of sensitive vegetation and browsing on remnant monsoon forest during the harsh late dry season when native pasture quantity and quality is declining (Bowman et al 2008;Braithwaite et al 1984;Petty et al 2007;Werner 2005;Werner et al 2006). Economically, buffalo are a major threat to Australia's livestock industry as hosts and vectors for diseases such as foot-and-mouth (Cousins and Roberts 2001;Ward et al 2007), and their broad dietary niche allows them to compete with cattle for pasture during the dry season (Bowman et al 2010). Socially, they pose a danger to human safety, especially for indigenous Australians in rural and remote areas (Albrecht et al 2009).…”

Section: Introductionmentioning

confidence: 99%