Better codes of practice for control of feral animals

24 02 2023

From time to time I turn my research hand to issues of invasive species control, for example, from manipulating pathogens to control rabbits, to island eradication of feral cats and pigs, to effective means to control feral deer.

Not only do invasive species cost well over $1.7 trillion (yes, that’s trillion, with 12 zeros) each year in terms of damage and control (a minimum of $25 billion per year in Australia alone), they are one of the main drivers of biodiversity loss globally. So, if you baulk at lethal forms of control of invasive species, you are simultaneously stating that you’re fine with the torture and death of millions (if not, billions) of native animals each year.

Thanks to the collaborative and evidence-driven foresight of my colleagues at PIRSA Biosecurity and Landscape Boards, I was recently involved in more research examining the most efficient, cost-effective, and humane ways to cull feral dear in South Australia. The resulting paper is now in review in NeoBiota, but we have also posted a pre-print of the article.

Feral deer are a real problem in Australia, and South Australia is no exception. With six species of feral deer in the country already (fallow Dama dama, red Cervus elaphus, hog Axis porcinus, chital A. axis), rusa C. timorensis, and sambar Rusa unicolor deer), fallow deer are the most abundant and widespread. These species are responsible for severe damage to native plants, competition with native animals, economic losses to primary industries (crops, pastures, horticulture, plantations), and human safety risks from vehicle collisions. Feral deer are also reservoirs and vectors of endemic animal diseases and have the potential to transmit exotic animal diseases such as foot-and-mouth. If left uncontrolled, within 30 years the economic impacts of feral deer could reach billions of dollars annually.

Read the rest of this entry »




Video explainer — nasty alien species in Australia

15 09 2021

You know you’ve made it to the big time in Australia when Behind The News does a story on your research. Practically every kid in Australia watches the show at some point during their school years.

Although this was produced last month, I thought I’d post the entire 4-minute video here for your viewing pleasure.

When you popularise your research story for kids, it really gets the message across well.

Thank you, Natasha and BTN for this opportunity.






Killing (feral) cats quickly (and efficiently)

20 05 2021

I’m pleased to announce the publication of a paper led by Kathryn Venning (KV) that was derived from her Honours work in the lab. Although she’s well into her PhD on an entirely different topic, I’m overjoyed that she persevered and saw this work to publication.

Here, killa, killa, killa, killa …

As you probably already know, feral cats are a huge problem in Australia. The are probably the primary reason Australia leads the world in mammal extinctions in particular, and largely the reason so many re-introduction attempts of threatened marsupials fail miserably only after a few years.

Feral cats occupy every habitat in the country, from the high tropics to the deserts, and from the mountains to the sea. They adapt to the cold just as easily as they adapt to the extreme heat, and they can eat just about anything that moves, from invertebrates to the carcases of much larger animals that they scavenge.

Cats are Australia’s bane, but you can’t help but be at least a little impressed with their resilience.

Still, we have to try our best to get rid of them where we can, or at least reduce their densities to the point where their ecological damage is limited.

Typically, the only efficient and cost-effective way to do that is via lethal control, but by using various means. These can include direct shooting, trapping, aerial poison-baiting, and a new ‘smart’ method of targeted poison delivery via a prototype device known as a Felixer™️. The latter are particularly useful for passive control in areas where ground-shooting access is difficult.

A live Felixer™️ deployed on Kangaroo Island (photo: CJA Bradshaw 2020)

A few years back the federal government committed what might seem like a sizeable amount of money to ‘eradicate’ cats from Australia. Yeah, good luck with that, although the money has been allocated to several places where cat reduction and perhaps even eradication is feasible. Namely, on islands.

Read the rest of this entry »




South Australia is still killing dingoes

14 04 2020

As we did for Victoria, here’s our submission to South Australia’s proposed changes to its ‘wild dog’ and dingo policy (organised again by the relentless and venerable Dr Kylie Cairns):

JE201608161745

© Jason Edwards Photography

14 April 2020

The Honourable Tim Whetstone MP, Minister for Primary Industries and Regional Development, South Australia

RE: PROPOSED CHANGES TO THE SA WILD DOG AND DINGO POLICY

Dear Minister,

The undersigned welcome the opportunity to comment on the proposed changes to the South Australian (SA) Government’s ‘Wild dog and Dingo’ declared animal policy under section 10 (1)(b) of the Natural Resources Management Act 2004. The proposed changes raise serious concerns for dingoes in SA because it:

1. Requires all landholders to follow minimum baiting standards, including organic producers or those not experiencing stock predation.

  • Requires dingoes within Ngarkat Conservation Park (Region 4) to be destroyed, with ground baiting to occur every 3 months.
  • Requires ground baiting on land irrespective of whether stock predation is occurring or not, or evidence of dingo (wild dog) presence.

2. Allows aerial baiting of dingoes (aka wild dogs) in all NRM regions – including within National Parks.

3. Uses inappropriate and misleading language to label dingoes as “wild dogs”

We strongly urge the PIRSA to reject the proposed amendments to the SA wild dog and dingo policy. Instead the PIRSA should seek consultation with scientific experts in ecology, biodiversity and wildlife-conflict to develop a policy which considers the important ecological and cultural identity of the dingo whilst seeking to minimise their impact on livestock using best-practice and evidence-based guidelines. Key to this aim, livestock producers should be assisted with the help of PIRSA to seek alternative stock protection methodology and avoid lethal control wherever possible. On the balance of scientific evidence, protection of dingoes should be enhanced rather than diminished. Widespread aerial baiting programs are not compatible with the continued persistence of genetically intact and distinct dingoes in SA.

In this context, we strongly emphasise the following points: Read the rest of this entry »





Victoria, please don’t aerial-bait dingoes

10 10 2019

Here’s a submission to Victoria’s proposed renewal of special permission from the Commonwealth to poison dingoes:

dingo with bait

08 October 2019

Honourable Lily D’Ambrosio MP
Minister for Energy, Environment and Climate Change
Level 16, 8 Nicholson Street, East Melbourne, VIC 3002

lily.dambrosio@parliament.vic.gov.au

cc:

The Hon Jaclyn Symes, Minister for Agriculture, Victoria

(jaclyn.symes@parliament.vic.gov.au)

Dr Sally Box, Threatened Species Commissioner

(ThreatenedSpeciesCommissioner@environment.gov.au)

The Hon Sussan Ley MP, Minister for Environment, Australia

(Farrer@aph.gov.au)

RE: RENEWAL OF AERIAL BAITING EXEMPTION IN VICTORIA FOR WILD DOG CONTROL USING 1080

Dear Minister,

The undersigned welcome the opportunity to comment on the proposed renewal of special permission from the Commonwealth under Sections 18 and 18A of the Environment Protection and Biodiversity Conservation Act 1999 (Commonwealth) to undertake aerial 1080 baiting in six Victorian locations for the management of ‘wild dogs’. This raises serious concerns for two species listed as threatened and protected in Victoria: (1) dingoes and (2) spot-tailed quolls (Dasyurus maculatus).

First, we must clarify that the terminology ‘wild dog’ is not appropriate when discussing wild canids in Australia. One of the main discussion points at the recent Royal Zoological Society of NSW symposium ‘Dingo Dilemma: Cull, Contain or Conserve’ was that the continued use of the terminology ‘wild dog’ is not justified because wild canids in Australia are predominantly dingoes and dingo hybrids, and not, in fact, feral domestic dogs. In Victoria, Stephens et al. (2015) observed that only 5 out of 623 wild canids (0.008%) sampled were feral domestic dogs with no evidence of dingo ancestry. This same study determined that 17.2% of wild canids in Victoria were pure or likely pure dingoes and 64.4% were hybrids with greater than 60% dingo ancestry. Additionally, comparative studies by Jones (1988, 1990 and 2009) observed that dingoes maintained a strong phenotypic identity in the Victorian highlands over time, and perceptively ‘wild dog’ like animals were more dingo than domestic dog.

As prominent researchers in predator ecology, biology, archaeology, cultural heritage, social science, humanities, animal behaviour and genetics, we emphasise the importance of dingoes in Australian, and particularly Victorian, ecosystems. Dingoes are the sole non-human, land-based, top predator on the Australian mainland. Their importance to the ecological health and resilience of Australian ecosystems cannot be overstated, from regulating wild herbivore abundance (e.g., various kangaroo species), to reducing the impacts of feral mesopredators (cats, foxes) on native marsupials (Johnson & VanDerWal 2009; Wallach et al. 2010; Letnic et al. 20122013; Newsome et al. 2015; Morris & Letnic 2017). Their iconic status is important to First Nations people and to the cultural heritage of all Australians. Read the rest of this entry »





Save a jaguar by eating less meat

8 10 2018

Kaayana

My encounter with Kaayana in Kaa-Iya National Park in the Bolivian Chaco. Her cub was around but cannot be seen in the photo

I was trapped. Or so I thought.

The jaguar came towards me on the dirt road, calmly but attentively in the dusky light, her nearly full grown cub behind her. Nervous and with only a torch as defence, I held the light high above my head as she approached, trying to look taller. But she was merely curious; and, after 20 minutes, they left. I walked home in the thickening darkness, amazed at having come so close to South America’s top predator. We later named this mother jaguar ‘Kaayana’, because she lives inside Kaa-Iya National Park in the Bolivian Chaco. My fascination with jaguars has only grown since then, but the chances of encountering this incredible animal in the wild have shrunk even since that night.

A few years after that encounter, I’m back to study jaguars in the same forest, only now at the scale of the whole South American Gran Chaco. Jaguars are the third largest cats in the world and the top predators across Latin America. This means that they are essential for keeping ecosystems healthy. However, they are disappearing rapidly in parts of their range.

Understanding how and where the jaguar’s main threats — habitat destruction and hunting — affect them is fundamental to set appropriate strategies to save them. These threats are not only damaging on their own, but they sometimes act simultaneously in an area, potentially having impacts that are larger than their simple sum. For instance, a new road doesn’t only promote deforestation, it also increases hunters’ ability to get into previously inaccessible forests. Similarly, when the forest is cut for cattle ranching, ranchers often kill jaguars for fears of stock loss.

Kaayana & kittens

Kaayana was seen years later by Daniel Alarcón, who took much better photos of her and her new cubs

However, the interactions between these threats are still not fully understood. In our new study, just published in the journal Diversity and Distributions, we developed a new framework to quantify how and where habitat destruction and hunting risk acted together over three decades, at the expense of highly suitable jaguar habitat in the Gran Chaco. We also analyzed how well the different Chaco countries — Bolivia, Paraguay and Argentina — and their protected areas maintained key jaguar habitat. Read the rest of this entry »





Minister, why is the dingo no longer ‘fauna’?

7 09 2018

dead dingoSo, a few of us have just submitted a letter contesting the Western Australia Government’s recent decision to delist dingoes as ‘fauna’ (I know — what the hell else could they be?). The letter was organised brilliantly by Dr Kylie Cairns (University of New South Wales), and she and the rest of the signatories have agreed to reproduce the letter in full here on ConservationBytes.com. If you feel so compelled, please voice your distaste of this decision officially by contacting the Minister (details below).

CJA Bradshaw

Honourable Stephen Dawson MLC
Minister for Environment; Disability Services
Address: 12th Floor, Dumas House
2 Havelock Street, WEST PERTH WA 6005
(minister.dawson@dpc.wa.gov.au)

cc: Department of Biodiversity, Conservation and Attractions (biodiversity@dbca.wa.gov.au)
cc: Brendan Dooley (brendan.dooley@dpc.wa.gov.au)

Dear Minister,

The undersigned welcome the opportunity to comment on and recommend alteration of the proposed section (9)(2) order of the Biodiversity Conservation Act 2016 (BC Act) that changes the listing of the dingo from “fauna” to “non-fauna” in Western Australia. Removing the “fauna” status from dingoes has serious consequences for the management and conservation of this species and other native biota it benefits. Currently, dingoes are classed as A7, or fauna that requires a management policy. The proposed section (9)(2) order will move dingoes (as “non-fauna”) to the A5 class, meaning that dingoes must be (lethally) controlled and there will be no obligation for the Department of Biodiversity, Conservation and Attractions to have an appropriate management policy (or approval).

Currently, under the Wildlife Conservation Act 1950 (WC Act) the dingo is considered “unprotected” fauna allowing management under a Department of Biodiversity, Conservation and Attractions management policy. A section (9)(2) order demoting dingoes to “non-fauna” will remove the need for Department of Biodiversity, Conservation and Attractions management policy and instead mandate the lethal control of dingoes throughout Western Australia.

As prominent researchers in top predator ecology, biology, cultural value and genetics, we emphasise the importance of dingoes within Australian, and particularly Western Australia’s ecosystems. Dingoes are indisputably native based on the legislative definition of “any animal present in Australia prior to 1400 AD” from the BC Act. Dingoes have been present in Australia for at least 5000 years. On the Australian mainland they are now the sole non-human land-based top predator. Their importance to the ecological health and resilience of Australian ecosystems cannot be overstated. Read the rest of this entry »





Biodiversity is everyone’s responsibility

13 07 2018

Workspace: Team Of Diverse Workers Put Hands TogetherI’m not sure if many South Australians are aware of this, but the Parliamentary Inquiry into Biodiversity by the Environment, Resources and Development Committee presented a report to the 53rd Parliament of South Australia in March 2017. I thought it worthwhile reproducing their executive summary here on CB.com (I’ve highlighted the text that I deem to be rather insightful and simultaneously damning from our own elected government representatives):

This report summarises the findings and recommendations of the South Australian Parliament’s Environment, Resources and Development Committee’s inquiry into biodiversity in South Australia. Specifically, the inquiry investigated the regulatory and policy framework to determine whether it appropriately supports terrestrial and marine ecological processes, biodiversity values and abates species extinction.

The Committee found that in spite of the efforts of the State and Federal governments, industry and private landholders in South Australia, the condition of biodiversity in the State continues to decline. Species extinctions have occurred in the past and a further “extinction debt” still exists. There is no reason to believe that this trend will improve without a change to the way we approach biodiversity conservation.

A key theme to emerge from the Inquiry is that biodiversity conservation needs to be everyone’s responsibility; State and Federal government, industry, the broader community, and private landholders.

This also means that biodiversity conservation needs to occur across both public and private land, with actions coordinated at a landscape scale.

Making biodiversity conservation everyone’s responsibility requires a range of measures, including legislative reform, improved management of threats and greater involvement of the community. The provision of greater resources would yield faster results.

This report has focused on several key themes that emerged from submissions to the Inquiry.

Regulating for better biodiversity – South Australia’s legislative framework

South Australia’s current legislative framework does not provide for optimum biodiversity outcomes.

Three key issues contribute to this –

  • an out-of-date suite of environmental legislation that lacks cohesion and consistency, particularly regarding enforcement and compliance provisions;
  • inadequate and incomplete processes for identifying and protecting at-risk elements that need special measures (e.g. for protection of specific threatened species and ecological communities); and
  • inadequate consideration of biodiversity conservation in legislation that regulates human activities. In particular, there is a lack of cohesion between the environmental legislative and policy framework and land use planning, assessment and approval.
  • Statutory fragmentation of biodiversity considerations – that is, consideration of different aspects of biodiversity under different pieces of legislation – results in lack of cohesion and consistency, duplication and inefficiency, and makes it difficult to implement a landscape approach or to identify strategic opportunities and risks.

Taken as a whole, current enforcement provisions do not provide for effective and proportionate compliance action. Enforcement and compliance provisions across the relevant legislation are uneven in their approach. For example, penalties appear to be disproportionate and not risk-based (although there are some exceptions). Modern enforcement tools such as compliance orders, civil remedies and alternative penalties (such as administrative penalties, payment of damages including exemplary damages, remediation orders etc) are not included in all relevant legislation. There is some duplication in offences and inconsistency in the types of sanctions and penalty ranges.

There is an urgent need to amend the legislative framework to support any attempt to improve biodiversity outcomes.

The best approach will be based on clear, shared responsibility for biodiversity outcomes, supported by individual accountability. However, such a change will require policy development and drive.

To ensure forward momentum and improvements in the short term while developing the policy settings to support such a step-change, a staged approach could be implemented. There are various ways this could be achieved.

The Committee suggests a 3-stage approach to reforming the legislative framework. The Committee recommends the creation of a Biodiversity Expert Panel that is responsible for advancing this 3-stage approach.

  1. The first stage will involve amendments to improve operation and effectiveness of the regulatory regime within current policy settings, acknowledging that as a result of Stage 3, provisions may be altered or moved into different pieces of legislation. Amendments generally would be to the existing ‘environmental’ Acts, and primarily to the National Parks and Wildlife Act 1972 and Native Vegetation Act 1991. They would include many of the specific areas for amendment identified in EDO submissions (2011 & 2015) as well as in the SA Government submission, for example, beginning with amendments to improve current environmental legislation.
  2. Stage 2 would progress to amendments to improve integration between Acts and improve support for landholders and community participation.
  3. Stage 3 would implement a system whereby all resource use and management would be managed by one piece of legislation, with protection of biodiversity and sustainable development at its core. Provisions for protected area management, and for the scientific work involved in identifying threatened species and communities, may be contained in separate legislation.

Threats, ecological resilience and restoration

The State’s native biodiversity is facing myriad of current threats, including habitat loss and fragmentation (due to development and changing land-use), pest plants and animals, and control burn regimes. There is a need for more stringent vegetation protection, better informed and enacted control and management strategies of known pest plants and animals, and a revision of burning regimes.

Future threats to the State’s biodiversity will be largely driven by climate change impacts and the interaction with existing major threats (e.g. urbanisation and changing land use). Adequately preparing for and managing such future threats will require knowledge of projected changes and pro-active preparation for such changes.

Working with the community

Involvement of the community is an essential part of any biodiversity conservation strategy for the State. It is a foundation stone for moving to a point where biodiversity conservation is everyone’s business.

Community engagement will become increasingly important for biodiversity conservation, especially given the growing role of volunteers to support works on public land as well as the voluntary conservation efforts of private landholders. The expanding role of volunteers reenforces that biodiversity conservation is everyone’s business.

South Australia’s approach to biodiversity conversation on private land needs to be reinvigorated.

Cross cutting themes

There were several cross cutting themes identified in submissions to the Inquiry. There was broad recognition of the strong cultural and historic significance of elements of biodiversity to Aboriginal people, and that this is often poorly understood outside those communities. Continuing to identify ways for Aboriginal people to contribute to land and water management in South Australia remains a priority.

With respect to knowledge generation, critical knowledge gaps exist that need to be filled and existing knowledge is not being adequately understood, communicated or applied. From a resourcing perspective, there is concern that insufficient funds are being allocated to biodiversity conservation, which is affecting work on public and private lands.

The management of over-abundant species in South Australia remains a challenge, noting the recent impacts of long-nose fur seals in the Lower Lakes and Coorong, and ongoing concerns regarding the impact of animals such as little corellas and some species of kangaroos on negative vegetation.

 





Influential conservation ecology papers of 2017

27 12 2017

Gannet Shallow Diving 03
As I have done for the last four years (20162015, 2014, 2013), here’s another retrospective list of the top 20 influential conservation papers of 2017 as assessed by experts in F1000 Prime.

Read the rest of this entry »





What’s in a name? The dingo’s sorry saga

30 01 2015

bad dingoThe more I delve into the science of predator management, the more I realise that the science itself takes a distant back seat to the politics. It would be naïve to think that the management of dingoes in Australia is any more politically charged than elsewhere, but once you start scratching beneath the surface, you quickly realise that there’s something rotten in Dubbo.

My latest contribution to this saga is a co-authored paper led by Dale Nimmo of Deakin University (along with Simon Watson of La Trobe and Dave Forsyth of Arthur Rylah) that came out just the other day. It was a response to a rather dismissive paper by Matt Hayward and Nicky Marlow claiming that all the accumulated evidence demonstrating that dingoes benefit native biodiversity was somehow incorrect.

Their two arguments were that: (1) dingoes don’t eradicate the main culprits of biodiversity decline in Australia (cats & foxes), so they cannot benefit native species; (2) proxy indices of relative dingo abundance are flawed and not related to actual abundance, so all the previous experiments and surveys are wrong.

Some strong accusations, for sure. Unfortunately, they hold no water at all. Read the rest of this entry »





It’s not all about cats

20 10 2014

Snake+OilIf you follow any of the environment news in Australia, you will most certainly have seen a lot about feral cats in the last few weeks. I’ve come across dozens of articles in the last week alone talking about the horrendous toll feral cats have had on Australian wildlife since European arrival. In principle, this is a good thing because finally Australians are groggily waking to the fact that our house moggies and their descendants have royally buggered our biodiversity. As a result, we have the highest mammal extinction rate of any country.

But I argue that the newfound enthusiasm for killing anything feline is being peddled mainly as a distraction from bigger environmental issues and to camouflage the complete incompetence of the current government and their all-out war on the environment.

Call me cynical, but when I read headlines like “Australia aims to end extinction of native wildlife by 2020” and Environment Minister Hunt’s recent speech that he has “… set a goal of ending the loss of mammal species by 2020“, I get more than just a little sick to the stomach.

What a preposterous load of shite. Moreover, what a blatant wool-pulling-over-the-eyes public stunt. Read the rest of this entry »





Essential role of carnivores on the wane

10 01 2014

© Luca Galuzzi www.galuzzi.it

© Luca Galuzzi http://www.galuzzi.it

This interesting review has just come out in Science, and because I was given a heads-up about it, I decided to do a F1000 recommendation. That’s more or less what follows, with some additional thoughts.

Ripple and colleagues can perhaps be excused for stating what might appear to many ‘in the biz’ to be blatantly obvious, but their in-depth review of the status of the world’s carnivores is a comprehensive overview of this essential guild’s worldwide plight. It not only represents an excellent teaching tool, the review elegantly summarises the current status of these essential ecosystem engineers.

The world’s 245 terrestrial carnivores might seem to be ecologically redundant to the informed given their natural rarity, low densities and cryptic behaviour, but nothing could be farther from the truth. Ecologists have only within the last decade or so revealed the essential ecosystem functions of these species (see former posts on CB.com here, here and here). The review focuses on the largest and most well-studied species, but the trends likely apply across most of the order. Read the rest of this entry »





Can Australia afford the dingo fence?

18 05 2012

I wrote this last night with Euan Ritchie of Deakin University in response to some pretty shoddy journalism that misrepresented my comments (and Euan’s work). Our article appeared first in The Conversation this morning (see original article).

We feel we have to set the record straight after some of our (Bradshaw’s) comments were taken grossly out of context, or not considered at all (Ritchie’s). A bubbling kerfuffle in the media over the last week compels us to establish some facts about dingoes in Australia, and more importantly, about how we as a nation choose to manage them.

A small article in the News Ltd. Adelaide Advertiser appeared on 11 May in which one of us (Bradshaw) was quoted as advocating the removal of the dingo fence because it was not “cost effective” (sic). Despite nearly 20 minutes on the telephone explaining to the paper the complexities of feral animal management, the role of dingoes in suppressing feral predators, and the “costs” associated with biodiversity enhancement and feral control, there wasn’t a single mention of any of this background or justification.

Another News Ltd. article denouncing Ritchie’s work on the role of predators in Australian ecosystems appeared in The Weekly Times the day before, to which Ritchie responded in full.

So it’s damage control, and mainly because we want to state categorically that our opinion is ours alone, and not that of our respective universities, schools, institutes or even Biosecurity SA (which some have claimed or insinuated, falsely, that we represent). Biosecurity SA is responsible for, inter alia, the dingo fence in South Australia. Although our opinions differ on its role, we are deeply impressed, grateful and supportive of their work in defending us from biological problems. Read the rest of this entry »





Student opportunities with Australian Wildlife Conservancy

8 09 2010

A colleague of mine, Dr. Matt Hayward of the Australian Wildlife Conservancy (AWC), asked me to circulate some Honours, MSc and PhD student project opportunities. I thought this would be best done by publishing the call as a blog post.

The AWC is a non-government, non-profit organisation dedicated to the conservation of Australia’s wildlife and their habitats. AWC’s south-east region has a team of 7 ecologists who work closely with the land managers to carry out AWC’s Conservation and Science Program. The Science Program includes strategic research designed to help us manage threatened species more effectively. Several of these research projects are suitable for Honours, Masters or PhD projects.

This prospectus provides an outline of the student projects that are currently on offer in the south-east region. The majority of the projects are based on one sanctuary, although some aspects of the research may be done on other AWC sanctuaries and/or government conservation areas.

AWC will partially support these projects with equipment, staff time and expertise, and accommodation. In some cases, AWC may also provide some vehicle use and office facilities onsite at The Scotia Field Research Centre. We anticipate these projects will be collaborative efforts with input from students, academics and AWC staff, with appropriate acknowledgement for all involved. These projects are offered on a first in, first approved basis and have been offered to multiple universities.

More details on the sanctuaries and AWC are available here. If you are keen do one of these projects, please contact Matt Hayward and we will then formulate a research proposal and research agreement. Eight project descriptions follow. Read the rest of this entry »





Classics: Mesopredator Release

17 03 2010

© J. Short

Although popularised by Crooks & Soulé (1999), Soulé et al. (1988) first gave us the term that described how entire ecosystems can become unbalanced by a reduction of a higher trophic-level predator exerting so-called ‘top-down’ control on the abundance of species occupying lower trophic levels.

The idea had theoretical support in ecology (Wright et al. 1994; Litvaitis & Villafuerte 1996), but it was not until Soulé and colleagues described how the decline of dominant predators combines with habitat fragmentation to release top-down pressure on smaller predators, thereby increasing predation rates on prey lower down the trophic web.

Crooks & Soulé (1999) described an example where the decline in coyotes (Canis latrans) in combination with urbanisation-driven habitat fragmentation led to an increase in cat (Felis catus) densities and the subsequent decline in scrub-breeding birds. More recent examples attest to the importance of the mesopredator release phenomenon: Myers et al. (2007) described how the decline in large coastal shark species has allowed mesopredator cownose rays (Rhinoptera bonasus) to increase, leading to a reduction in commercially important shellfish densities; and Johnson et al. (2007) showed how dingoes (Canis lupus dingo) in Australia suppress populations of exotic predators such as cats and foxes, leading to more locally abundant populations of native marsupials (see previous post).

Conservation biologists have benefited from this knowledge because we’ve realised that top-order predators affect far more than their immediate prey. These examples really hit home how a fully functional community is required for ecosystem stability, so we should strive to preserve complete complements of communities, not just our favourite species.

CJA Bradshaw

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Feral predators – ‘super’ cats, foxes and dingoes

3 07 2008

cat and bilbyHere’s one to get us going. A recent news item on ABC News discusses the prospect of importing so-called ‘super cats’ (‘savannah cats’ = domestic cat x African serval) into Australia. Although most of the items and people commenting on the subject deplore the very notion, I cannot believe that there was the legal capacity to import these things in the first place! Or indeed, that the company attempting to commit the heinous conservation crime has the right even to exist in this country. You’d think we’d learn after swamp buffalo, cane toads, foxes and a host of other alien nasties have caused Australian fauna to experience some of the higher rates of extinction known in the modern context. Indeed, it is my opinion that all cats (domestic and otherwise) should be declared illegal in Australia and destroyed. This is where it gets interesting though. One for the ‘papers to watch’ categories is by a mate and colleague of mine, Professor Chris Johnson of James Cook University in Townsville. He and his colleagues last year published a paper in Proc. R. Soc. B. called ‘Rarity of a top predator triggers continent-wide collapse of mammal prey: dingoes and marsupials in Australia‘.

dingo-21Here, they showed how dingoes (themselves ‘alien species’, but from some time ago) actually appear to suppress the populations of more recent alien predator arrivals (e.g., cats and foxes). The upshot is that more dingoes = fewer cats/foxes = more native fauna. Brilliant! I hope we can say in a few years how the careful management of dingoes and promotion of their conservation has benefitted an array of threatened marsupials in Australia. Well done Chris and colleagues.

CJA Bradshaw