Preying on predators: trophic cascade unharmed by dingo culling to protect livestock

Posted by Biome on 18th July 2013 - 2 Comments


In Australia, the culling of dingoes is a relatively common practice to protect livestock. However, these culls are often strongly opposed on the grounds of the ecological effect they may have on the trophic cascade. According to the mesopredator theory, culling a top predator such as the dingo will result in an increased abundance of mesopredators – feral cats, red foxes and goannas – which in turn increases predation in lower trophic levels.

In a recent study published in Frontiers in Zoology, Benjamin Allen from the University of Queensland, and colleagues investigate the outcomes of top-predator control on smaller sympatric mammal and reptile predators in Australia.

Location of the nine study sites used by Benjamin Allen and colleagues. Image source: Frontiers in Zoology, 2013, 10:39

Allen and colleagues conducted a series of manipulative experiments at nine sites spanning five ecosystem types across the Australian continental rangelands to investigate the responses of mesopredators to contemporary poison-baiting programs. They show that culling dingoes within conventional limits does not result in an increased presence of mesopredators, and therefore contradicts the idea that this effect can result in conservation issues for smaller threatened Australian species.

The researchers suggest that careful planning of dingo culls, such as around the peak cattle calving season, provides livestock producers with a window of opportunity to reduce livestock predation during high-risk times while still maintaining ecological diversity of the trophic cascade.

Allen, who led the study, explained, “Dingo populations recovered to pre-control levels within months, which means that baiting does not create the conditions required for mesopredators to increase. This helps us to understand why, despite years of control measures the numbers of dingoes in Australia is at an all time high.”

 

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  • trippa

    Good points Dennis, also I wonder if the researchers did an appropriately timed baseline count of feral mesopredators. Perhaps mesopredators were already at full carrying capacity at a time of abundance and no matter what you did there numbers could not increase. Furthermore if the culling occurred as climatic conditions began to deteriorate from the ideal, a balance would occur where the numbers of prey that the top predators would eat would alternatively be taken by the mesopredators that have filled the niche that the top predators previously occupied. This would result in no net increase or decrease in mesopredators but the needless culling of top predators that might of otherwise reduced mesopredator numbers.