The office of Australia’s Chief Scientist has featured me among it’s “Australian science superheroes”!
The office of Australia’s Chief Scientist has featured me among it’s “Australian science superheroes”!
Published in: Biodiversity and Conservation
Over the last century, changing public attitudes about the value of wildlife have triggered substantial changes in species management that have both benefited and hindered conservation efforts. Understanding and integrating contemporary public values is therefore critical for effective conservation outcomes.
Using historic and contemporary examples, we highlight how public attitudes—expressed through the media and campaigns—are shaping the management of introduced and native species, as values shift towards animal welfare and mutualism. We focus on the issue of deliberate human-caused killing of wildlife, because protests against such management have disrupted traditional political and management structures that favoured eradication of wildlife across many jurisdictions and ecological contexts. In doing so, we show that it is essential to work with multiple stakeholder interest groups to ensure that wildlife management is informed by science, while also supported by public values. Achieving this hinges on appropriate science communication to build a better-informed public because management decisions are becoming increasingly democratised.
Authors: Lily M Van Eeden, Mathew S Crowther, Chris R Dickman, David W Macdonald, William J Ripple, Euan G Ritchie, and Thomas M Newsome
Published in: Conservation Biology (early view)
Large carnivores are persecuted globally because they threaten human industries and livelihoods. How this conflict is managed has consequences for the conservation of large carnivores and biodiversity more broadly. Mitigating human-predator conflict should be evidence-based and accommodate people’s values while also protecting carnivores.
Despite much research into human-large carnivore coexistence strategies, there have been limited attempts to document the success of conflict mitigation strategies on a global scale.
We present a meta-analysis of global research on conflict mitigation between large carnivores and humans, focusing on conflicts that arise from the threat that large carnivores pose to livestock industries.
Overall, research effort and focus varied between continents, aligning with the different histories and cultures that shaped livestock production and attitudes towards carnivores.
Of the studies that met our criteria, livestock guardian animals were most effective at reducing livestock losses, followed by lethal control, although the latter exhibited the widest variation in success and the two were not significantly different. Financial incentives have promoted tolerance in some settings, reducing retaliatory killings.
In future, coexistence strategies should be location-specific, incorporating cultural values and environmental conditions, and designed such that return on financial investment can be evaluated. Improved monitoring of mitigation measures is urgently required to promote effective evidence-based policy.
By Thomas Newsome (Deakin University)
Dingoes could be the key to controlling red foxes and other invasive predators, but only if we encourage them in large enough numbers over a wide enough area, our research shows.
Interest in re-introducing or restoring top predators, like dingoes and wolves, has been fuelled by recent studies demonstrating their important roles in their ecosystems. They can especially be vital in suppressing the abundance of lower-order competitors or “mesopredators”, like red foxes and possibly feral cats (which can have devastating effects on native species).
But researchers have found top predators aren’t always successful in reducing mesopredator numbers. Until now, such variation has been linked to human presence, land-use changes and environmental factors such as landscape productivity.
However, our research, published yesterday in Nature Communications, found that a key factor for success is high numbers of dingoes and wolves across their natural range.
If you look at how species are typically distributed across a landscape – their range – ecological theory predicts there’ll be lower numbers at the outer edges of their range.
If you do need large numbers of top predators to effectively suppress mesopredators, the core of their range is potentially the best place to look.
We tested this idea, looking at the dingo in Australia and the grey wolf in North America and Europe. The mesopredators included the red fox in Australia, the coyote in North America and the golden jackal in Europe.
We used information from bounty hunting programs, as these provide data on predator numbers across a wide geographical area. In the case of Australia we used historic data from the 1950s, as this is the most recent reliable information about red fox and dingo distribution. The actual population numbers of red foxes and dingoes have changed substantially since then, but the nature of their interactions – which is what we were investigating – has not.
We determined that top predators exist in higher numbers at the core of their ranges in comparison to the edges. We then looked at mesopredator numbers across the range edges of their respective top predator.
The results, which were consistent across the three continents, suggest that top predators can suppress mesopredators effectively (even completely) but only in the core of their geographic range, where their numbers are highest.
In other words, abundant top predators can exert disproportionate mesopredator control once their numbers increase past a certain point.
The relationship we uncovered is now formalised as the “Enemy Constraint Hypothesis”. It could apply to other predator dyads, where two animals compete for similar resources – even relationships involving parasites and pathogens.
Our findings are important for understanding species interactions and niches, as well as the ecological role of top predators. It could explain why other studies have found top predators have little influence on mesopredators: they were looking at the edge, not the core, of the top predators’ range.
Dingoes can be vital for reducing red fox and possibly feral cat numbers. In our case studies the ranges of each top predator were limited primarily by human use of the land and intensive shooting, trapping and poisoning.
Killing pack animals like dingoes can fracture social groups, potentially altering their natural behaviour and interactions with other species. Future studies on predator interactions therefore need to consider the extent to which the animals are acting in response to human intervention.
If we want to benefit from the presence of top predators, we need to rethink our approach to management – especially where they are subjected to broad-scale control, as the dingo is in some parts of Australia.
Changing our relationship with top predators would not come without its challenges, but high extinction rates around the world (and especially in Australia) clearly indicate that we urgently need to change something. If this includes restoring top predators, then we need to think big.
Authors: Thomas M Newsome, Aaron C Greenville, Duško Ćirović, Christopher R Dickman, Chris N Johnson, Miha Krofel, Mike Letnic, William J Ripple, Euan G Ritchie, Stoyan Stoyanov and Aaron J Wirsing
Published in: Nature Communications, volume 8
Top predators can suppress mesopredators by killing them, competing for resources and instilling fear, but it is unclear how suppression of mesopredators varies with the distribution and abundance of top predators at large spatial scales and among different ecological contexts.
We suggest that suppression of mesopredators will be strongest where top predators occur at high densities over large areas. These conditions are more likely to occur in the core than on the margins of top predator ranges.
We propose the Enemy Constraint Hypothesis, which predicts weakened top-down effects on mesopredators towards the edge of top predators’ ranges.
Using bounty data from North America, Europe and Australia we show that the effects of top predators on mesopredators increase from the margin towards the core of their ranges, as predicted.
Continuing global contraction of top predator ranges could promote further release of mesopredator populations, altering ecosystem structure and contributing to biodiversity loss.
Newsome TM, Greenville AC, Ćirović D, Dickman CR, Johnson CN, Krofel M, Letnic M, Ripple WJ, Ritchie EG, Stoyanov S, Wirsing AJ (2017) Top predators constrain mesopredator distributions. Nature Communications, PDF DOI
Vast, ancient, nutrient-poor, with wild swings between droughts, floods and fires: this describes much of the Australian continent. Livestock grazing and farming in such a land is certainly not without its challenges.
Where we’ve failed to work with the local conditions, we see barren plains, dust storms, the extinction of native species, and the repossession of properties by banks, among many ills.
But such a dire picture is far from universal, and belies the fact that many who live on the land are also among our most innovative land managers. Many projects offer potential benefits for livestock production and the environment alike, but without support progress may be hindered.
One of the most contentious examples involves encouraging dingoes. Many pastoral areas require land managers to take “all reasonable and practical steps” to manage the risk of dingoes, which are classed as pest animals.
A Western Australian couple, David Pollock and Frances Jones, were recently featured on Australian Story for their decision to regenerate their property, Wooleen, by de-stocking, encouraging local flora and fauna, and investing in ecotourism.
Their neighbours, including sheep graziers whose stock are vulnerable to dingoes, feel this is an irresponsible decision. Graziers have a mandate to control dingoes (“wild dogs”, to many) and dingo-domestic dog hybrids — which can’t be easily and reliably distinguished in the wild.
While the impacts and merits of encouraging dingoes in sheep country are hotly debated, their role in the management of cattle stations is much better understood. But restrictive legislation and the stigma attached to dingoes are frustrating for those who see them as having a vital ecological and economic role for their properties.
Queensland grazier Angus Emmott writes that his beef cattle enterprise, Noonbah station, has benefited from leaving dingoes and kangaroos alone:
We run a beef cattle enterprise in the top end of the Queensland channel country, southwest of Longreach. As a part of our management plan, we leave the dingoes and the ’roos alone. We see a range of benefits to our operation.
When the dingoes don’t have their social structure disrupted by poison baiting, trapping and shooting, only the apex bitch breeds, once a year at most. These family groups have strictly defined ranges, and they kill or chase off other wild dogs or dingoes that intrude. They also keep kangaroos down to very low numbers, which is a huge benefit in regards to pasture growth and being able to rest our paddocks. The dingoes also keep down feral pig, cat and fox numbers.
Yes, dingoes do take some of our calves, but the benefits of pasture growth and feral animal control result in a net benefit of better land condition and a greater dollar return. Dingoes also benefit biodiversity conservation and soil condition. We acknowledge this management model does not work in sheep country, including for some of our nearby neighbours, and in these cases we need to look at different forms of management, such as fencing and/or companion and guardian animals.
Research supports the financial benefits of this approach in certain circumstances. Some studies have found that, perversely, taking lethal action against dingoes can increase the incidence of attacks on stock and boost the population of herbivores that compete with cattle for pasture.
Solutions for protecting livestock against attack, such as guardian dogs, are also at hand and may be considerably cheaper than constructing and maintaining extensive predator-proof fences. Livestock guardian dogs have been shown to be effective in numerous locations across Australia, on large and small grazing properties. But investment from state and federal government (and related agencies) aimed at encouraging such innovation has been lacking.
Regardless of whether graziers take the drastic steps seen at Wooleen, now is the time to reflect on the direction of Australia’s land management.
If we’re to overcome the many challenges we face, including the impacts of climate change on food production, then we need to support the bold new thinking emerging from rural and regional Australia, and our scientific institutions.
Seeing some of the worst land degradation first hand it’s easy to think that it’s all too hard and that environmental repair will take decades, if not centuries. This can invite inertia and apathy, the enemies of positive change.
But the stories of Wooleen, Noonbah and other innovators show us what is possible. Science has helped demonstrate ecological repair can happen faster and to a greater extent than many might appreciate.
Big changes certainly carry risks, and these must be managed carefully, but new and sometimes brave ideas will always improve our understanding of the land. Whatever the outcome, such knowledge helps guide better decisions for more sustainable grazing, farming and bio-diverse conservation.
I would like to acknowledge the contribution of Angus Emmott to this article.
By Tim Doherty (Deakin University), Aaron J Wirsing (University of Washington), Chris Dickman (University of Sydney), Dale Nimmo (Charles Sturt University), Euan Ritchie (Deakin University), and Thomas Newsome (Deakin University)
Humans and their canine companions share many close bonds. Wolves (Canis lupus) were the first animal domesticated by people, some time between 15,000 and 50,000 years ago.
There are now an estimated 1 billion domestic dogs across their near-global distribution.
Domestic dogs include feral and free-ranging animals (such as village and camp dogs), as well as those that are owned by and completely dependent on humans (pet dogs).
Our latest research reveals that the ecological “pawprint” of domestic dogs is much greater than previously realised.
Using the IUCN Red List of Threatened Species, we counted how many species are negatively affected by dogs, assessed the prevalence of different types of impacts, and identified regions with the greatest number of affected species.
We found that dogs are implicated in the extinction of at least 11 species, including the Hawaiian Rail and the Tonga Ground Skink. Dogs are also a known or potential threat to 188 threatened species worldwide: 96 mammal, 78 bird, 22 reptile and three amphibian species. This includes 30 critically endangered species, two of which are classed as “possibly extinct”.
These numbers place dogs in the number three spot after cats and rodents as the world’s most damaging invasive mammalian predators.
Even though dogs have an almost global distribution, the threatened species they are known to affect are concentrated in certain parts of the globe. South-East Asia, South America, Central America and the Caribbean each contain 28 to 30 threatened species impacted by dogs. Other hotspots include Australia, Micro/Mela/Polynesia and the remainder of Asia.
Predation was the most commonly reported impact of dogs on wildlife. The typically omnivorous diet of dogs means they have strong potential to affect a diversity of species. For instance, dogs killed at least 19 endangered Kagu (a ground-dwelling bird) in New Caledonia in 14 weeks. Threatened species with small population sizes are particularly vulnerable to such intense bouts of predation.
Aside from simply killing animals, dogs can harm wildlife in other ways, such as by spreading disease, interbreeding with other canids, competing for resources such as food or shelter, and causing disturbances by chasing or harassment. For example, contact with domestic dogs increases disease risk for endangered African Wild Dogs in Kenya.
Part of the problem is that when wild animals perceive dogs as a threat, they may change their behaviour to avoid them. One study near Sydney found that dog walking in parklands and national parks reduced the abundance and species richness of birds, even when dogs were restrained on leads.
None of the Red List assessments mentioned such indirect risk effects, which suggests that their frequency is likely to be much higher than reported.
Despite their widespread and sometimes severe impacts on biodiversity, dogs can also benefit some species and ecosystems.
For example, in Australia, the closely related dingo (Canis dingo) can suppress populations of introduced predators such as red foxes (Vulpes vulpes), and in doing so can benefit smaller native prey. It is possible that domestic dogs could perform similar ecological roles in some situations.
Dogs not only interact with wildlife, but can also attack and spread disease to humans, livestock and other domestic animals. As such, managing the problem requires looking at ecological, cultural and social perspectives.
Some of the regions with high numbers of species threatened by dogs are also hotspots for urbanisation and road building, which make it easier for dogs to access the habitats of threatened species. Urban development increases food waste, which feeds higher numbers of dogs. As dogs expand into new areas, the number of species they impact is likely to grow.
We can protect wildlife by integrating human health and animal welfare objectives into dog management. Vaccination and desexing campaigns can reduce disease risk and overpopulation problems. We should also focus on responsible dog ownership, removing dogs without owners, and reducing access to food waste.
Given the close relationship between humans and dogs, community engagement should form the basis of any management program. More research is needed to get a better picture of the scale of the problem, and of how dogs interact with other threats such as habitat loss. Such actions are critically important for ensuring the conservation of wildlife threatened by dogs around the world.