Reporting on failures

Admin Aridrecovery - Tuesday, February 07, 2017

Arid Recovery’s commitment to sharing all research outcomes for everyone to learn from


Arid Recovery’s ambitious goal is to see vulnerable native animals restored to Australia’s vast open landscapes, out of fences and roaming freely. To make any headway in this ambition it is essential to try new things, but this of course comes with risks. As is to be expected, we don’t always get the outcomes we want. Frequently when we try an idea it will fail. Over the last 20 years we have tested methods for establishing native animals outside of fences and found, that introduced cats and foxes usually overcome our efforts.

One of Arid Recovery’s objectives is to strive to publish everything: the good, the bad and the ugly. As we measure and monitor everything we do, these failures or setbacks are an opportunity to learn and further our understanding. We are not focused on good news stories, but on the only story that matters: what is actually happening.

We cannot hide from the fact that our conservation programs have led to animal deaths. Between 2006 and 2008 we ran the ‘Wild West’ project that was an attempt to establish a population of bilbies outside the reserve (read the paper). Enormous efforts went into feral cat and fox control with many hours put in by volunteers. We even tried training naïve bilbies to be wary of predators by exposing them to predator scents and models and associating them with an unpleasant experience. Despite our best efforts removing feral cats and foxes from quarterly aerial baiting, continual trapping and shooting, the attempt ultimately failed with the last bilby dying 19 months after release: a failure in most senses.






A bilby killed by a feral predator


However, we learnt so much from this failure. We now know that broad feral cat control is not necessarily that effective, but that targeted removal of individual killer cats may be. We learnt that training bilbies with scents and models of predators is no substitute for the real thing. These lessons are published in scientific journals, and have clearly shown us what we needed to do next. The experience led to our current project on Tackling Prey Naivety in collaboration with the University of NSW (and more here). Already there is success building on the foundation of the earlier failures.  We now have bilbies (and bettongs) coexisting with a low density population of cats.

There are other complexities and unexpected lessons learnt along the way too. The good news story of booming populations of threatened species reintroduced into the predator-proof reserve is not so simple. Our greatest success – returning some vulnerable mammals otherwise extinct on the mainland such as the Burrowing Bettong – has had a setback. Bettong numbers are now too high, damaging the condition of the vegetation in the reserve and reducing the food available for other species. Once again, by recognising the problem, analysing it, and not shying away from bad stories, we have been able to begin developing solutions. Currently we are testing one-way gates as a means for bettongs to disperse and relieve the pressure on the reserve, along with other options. Our commitment is that if this doesn’t work, we will still publish what we learn for the benefit of everyone.

Will these stories that are sometimes unsavoury cost us? It could taint our image in some people’s minds and could expose us to sound-bite criticisms from oversimplified media. But we believe this openness is critical to moving conservation forward in Australia.

We recognise that many organisations cannot often afford to stray from the good news stories to the same extent as we can by admitting the occasional failure. Politicians and public servants understandably wish to prevent government departments from being accused of ‘failing’ or ‘wasting tax dollars’, and big charities can ill afford to appear to ‘waste’ generous donations. This is in large part why so many insights and so much valuable information continue to lie in internal reports. It is an understandable waste, but a waste nonetheless.

We are optimistic that, collectively, we will eventually meet our goal of restoring lost mammals to Australia’s arid interior. One day, this battle may be over. Natives, cats and rabbits will, we hope, coexist with minimal intervention. To get there we need to build on our understanding of how arid ecosystems work and develop new methods for dealing with threats. Only by testing every assumption, by analysing every mistake, and by boldly trying risky ideas can we push our knowledge forward. To this end, we aim to publish papers on every one of our failures. By learning from these failures, not only we but also everyone else pushing conservation forward can gain some real ground.

20 years of cat control: keeping threatened species safe

Admin Aridrecovery - Monday, December 19, 2016


Buoyed after another successful week of cat control, Field and Maintenance Officer John Crompton and our dedicated volunteer shooters removed 13 cats and 4 foxes in one week. Each of the cats had between 1 and 5 native mice in their stomachs, including the threatened Plains Mouse. It is sobering to think of just how many animals these cats are killing every night, but we’re glad our feral predator control is making a difference.

Our feral predator control is partly about making a safe haven around the perimeter of the Arid Recovery fence, but also helps to keep cats and foxes out of the Reserve. Our fence is designed to be cat and fox proof, but we have to ensure there are no incursions of feral animals from damage to the fence.

Our floppy-top fence design is an extremely effective deterrent. Cats that attempt to breach the fence by pouncing on the floppy top are flung to the ground. But as everyone knows, feral cats are incredibly intelligent. If given enough time, and presented with a reward as good as the defenceless native animals inside, they will instantly take advantage of any weak point.

Our fence is currently our best defence against feral animals. Photo Credit: Kimberley Solly

Just recently, the September storm that cut off power to South Australia, also blew the floppy top inwards along sections of our western boundary. Not long afterwards we found cat tracks inside the Reserve.

Over the last 19 years, a few individual cats have breeched the fence like this. Removing them has been a herculean effort. It’s one thing to remove one cat of many in an open landscape, but to seek out and remove one lone cat in a sea of native animals is something else altogether. Great care must be taken when using traps and shooting. Usually the whole Arid Recovery team and volunteer community have to hunt intensively for months on end.

So our feral predator control strategy is to remove cats before they have time to study the fence for weaknesses. To this end, we created a permanent set of cat traps along the outside perimeter of the fence. To draw cats in, we have tried every lure imaginable: fish oil, cat urine piss and sound players that make meowing sounds. These typically catch between one and fives cats per week.

On top of these permanent traps, we also have a team of dedicated volunteer shooters. Feral control not only reduces the risk of incursion, it also creates a buffer zone protecting native animals around the perimeter of the reserve.  Some volunteer shooters have removed over 50 cats and foxes for us. No doubt many of the bilbies and bettongs of Arid Recovery owe their lives to their efforts.

John Crompton our Field and Maintenance Officer patrols the fence and permanent trap sites. Photo Credit: Charmayne Cronje

Unfortunately, no matter how much cat control we do, we will never eradicate cats from this region. There will always be new cats to wander in from elsewhere; whether they are strays from towns or ferals from far far away. But thanks to the rigours and dedicated efforts of staff and volunteers, we have at least kept their numbers lower than they would have been otherwise around the fence.

Our trapping and shooting efforts are not about hating cats and foxes, but about loving our native wildlife and doing everything possible to keep their populations strong. Please support our work managing the threat of feral cats at Arid Recovery. There are many ways you can get involved: you can volunteer, become a Friend of Arid Recovery, come out on a spotlighting tour, join one of our community events or support our work by donating or adopting a bettong or bilby.

Written By Hugh McGregor, in partnership with the University of Tasmania and National Environment Science Programme. 




Know thy enemy - What happens when you breed animals in an environment where there are no predators?

Admin Aridrecovery - Tuesday, October 18, 2016

There have been a few blogs along the way regarding my research of the Greater Bilby (Macrotis lagotis) at Arid Recovery (refresh your mind here, here and here). But as they say all good things must come to an end. Time certainly does go too quickly when you are having fun doing field work at Arid Recovery, especially when you are working with unique animals like the bilby. Two and half years ago I embarked on an amazing adventure that took me all the way from the yellow sands of Bondi Beach, Sydney, to the red desert of Roxby Downs, South Australia. As soon as I heard that there was a PhD project investigating the prey naïveté of Australian native mammals, like the bilby, I knew I had to be a part of it!


Figure 1: The Greater Bilby Photo credit: Lisa Steindler

Prior to European settlement the bilby was found over 70% of Australia. Unfortunately, today they are considered legally extinct in the wild in South Australia, New South Wales and Victoria. The biggest identified threat and cause for this decline has been the introduction of exotic predators, such as the red fox and feral cat.

Thanks to the amazing work by organisations, such as Arid Recovery, feral free reserves have been established. The bilby population at Arid Recovery has boomed within this ‘safe haven’ for reintroduced species. But what happens when you breed animals in an environment where there are no predators? Do they lose all recognition of predators? Can we release them outside the fence where there ARE feral cats, red foxes and dingoes? Like many others we want to see Australian mammals beyond the fence and back in the wild and my PhD research is a step in that direction.

Now onto some basic theory behind that term “prey naïveté”, what exactly does it mean?!  If a prey animal is able to recognise a predator, they may be able to decrease their chances of being eaten. This is often known as an ‘anti-predator’ response. Whether a prey animal is able to recognise a predator may be influenced by their lifetime experiences. Animals may learn through personal experience whether another animal is a friend or an enemy who wants to eat them. Sometimes prey may not be exposed to predators within their lifetime, but they are still able to recognise and respond to them (i.e. in the case of animals living within the Arid Recovery Reserve). Animals that have lived with a particular predator for hundreds and even thousands of years may have “hard wired” responses to this predator. On the other hand, sometimes isolation from all predators over an animal’s lifetime or over hundreds to thousands of years can lead to the loss of all ‘anti-predator’ behaviours – “prey naïveté”.  

Understanding if prey are able to recognise and respond to a predator is important.

Theories on prey predator discrimination and recognition are divided as to whether prey species’ ability to recognise and avoid predators is proportionate to the duration of evolutionary exposure to specific predators or is a result of more generalised discrimination processes. Moreover, the understanding of the timeframes necessary for prey species to maintain or acquire appropriate responses to introduced predators is poorly understood. To be able to answer the question of how we can teach our native animals to be more aware of introduced predators we first need to understand what their current level of understanding is.

I attached radio transmitters to 18 bilbies at Arid Recovery so that each day I could radio-track sleeping bilbies to their burrows. Faecal samples from cats, dogs and rabbits were placed on the outside of bilby burrows to see how they would respond, as bilbies often use their strong sense of smell to recognise predators. Remote cameras were used to film the response of bilbies to the olfactory cue as they emerged from their burrow. The idea was that bilbies had to decide whether it was safe enough to exit the burrows when the faeces were present. If they recognised the faeces as a threat, then they should be more hesitant to leave the burrow compared to when they did not recognise it as a threat.


Figure 2: I radiotracked 18 bilbies for three months with the help of wonderful volunteers.                 Photo credit: Lisa Steindler

Figure 3: Camera traps were used to film bilby emergence behaviour. Photo credit: Lisa Steindler

Video analysis of burrow emergence behaviour determined that bilbies were indeed more hesitant to leave the burrow when certain predator scent was present. Bilbies spent more time only partially emerged (with at most head and shoulders out) as opposed to fully emerged (standing quadrupedally or bi-pedally, fully emerged from burrow) from their burrows when dog faeces were present, in comparison to faeces of cats, rabbits and an unscented control. The Greater Bilby has shared over 3000 years of co-evolutionary history with dogs but less than 200 years with cats. The ability of prey species to respond to the odours of predators relates to their period of coexistence. The longer that you have known your predator over evolutionary time may influence whether you can recognise their odour, even if you aren’t currently living with them.



Figure 4 and 5: What was classified as a partially emerged bilby vs a fully emerged bilby.            Photo credit: Lisa Steindler

This research is only the starting point to seeing a future for bilbies beyond the fence. This research would suggest that despite at least 15 years of isolation from placental predators, bilbies retain some level of “hard wired” recognition of their historical predators (dingoes). The next question will be: Can they survive predation attempts by these predators? Can we teach them to be a bit more aware of introduced predators such as cats and foxes? And can adapt to live in a changing world outside the fence where these predators now exist?

Thanks to all the wonderful support from my supervisors, Arid Recovery staff, and volunteers along the way, I have had an amazing PhD journey that has led to many moments of blood, sweat and tears, a growing family of wonderful friends and precious memories of a unique, charismatic animal ... the bilby!!

Written by Lisa Steindler, PhD candidate with the UNSW. 


Prey switching - What will happen when the second strain of calicivirus hits?

Admin Aridrecovery - Monday, September 19, 2016

I am about to start a project here at Arid Recovery that will study how a new strain of a virus used to control rabbit numbers will affect the ecosystem here. What will a drop in rabbit numbers do to the population of cats and foxes, as well as our threatened native species?

The original strain of calicivirus is arguably Australia’s most successful biological control method – it had huge impact on rabbits, which have caused untold ecological damage across the country. When the virus was released in 1997, rabbits went from plague proportions to scarce in a matter of weeks.

Rabbits fighting back

Rabbit numbers have been slowly recovering since as they have been evolving immunity to the virus, but it is still out there doing its job such that rabbit numbers have never quite recovered to pre-1997 levels. The removal of so many rabbits from the landscape in a short space of time had a huge impact across the whole ecosystem.

Predators turn on the natives

Rabbit impacts have been studied in detail around Roxby Downs over the last 30 years - check this paper out! When the first calicivirus came through, the population rabbit numbers crashed to virtually nothing. This had major flow-on effects. With fewer rabbits, cats and foxes lost their main food source so not only did their populations plummet, but they also became a lot hungrier and turned to eating more native animals in a process known as prey switching (analyses found a greater proportion of native animals in fox and cat scats after calici).

This put extra pressure on many native species, and it is possible a population of rock-wallabies went extinct as a result (follow up here). In the long term however, the knockdown of rabbits appeared to have some incredible benefits. Cat and fox numbers fell and have stayed down since calici, and over the 20 years since many native animals have rebounded in South Australia including dusky hopping-mouse, plains mouse and the crest-tailed mulgara (read more here).

A new strain of virus is coming

There is a new strain of calicivirus on its way to Roxby, to which most rabbits here are yet to evolve any immunity. My project will look at how native prey species will be affected by controlling rabbit numbers with this new strain of the virus. I will be comparing the extent to which cats and foxes switch from hunting rabbits to killing native species, versus how much the populations of feral predator will fall or rise.

We have a perfect opportunity to test this near Roxby Downs in 2016/2017 as the new strain of calicivirus becomes established in the area. This new strain (RHDV2) is an altered form of the original, and has been killing many rabbits that are resistant to the original strain.

Originating in Canberra, it has moved across south-east Australia in a wave and is currently in the Flinders Ranges. It will create a neat before and after experiment. I will use the Arid Recovery Dingo Pen as a contained area where we can track exact numbers of cats, rabbits and native animals as the drama unfolds.

Cats with cameras

By tracking numbers and locations of native animals I can make a detailed analysis of exactly what happens when rabbit numbers crash. I will measure the extent of prey switching to find out how many more native animals are killed by cats after rabbit numbers fall.

To do this, I will need to follow cats on their daily journey of destruction. I’ve been fitting cats with video cameras to record what they hunt and how they behave, as well as using small GPS units so I can see where they go. Here is an example of one of my collared cats ready to hunt! This will enable me to measure the actual kill-rates of feral cats, and estimate the impact of their predatory behaviour on native animals before and after rabbit knockdown.

I will record the area covered by each feral cat, the number of rabbits and natives killed every 24 hours and the total number of animals killed by the whole population of cats. From this I can calculate the total predation pressure.

I may find that native animals are at their most vulnerable when rabbits decline and that during those times we should ramp up predator control. Or it might make no difference. What we learn will be useful for protecting vulnerable species that persist in refuges and for planning threatened species translocations.




Figures 2 and 3: Cats have been fitted with cameras in the Dingo Pen to observe predation and to document what occurs when the second strain of calicivirus strikes Roxby Downs. Photo credit: Hugh McGregor

Written By Hugh McGregor, in partnership with the University of Tasmania and National Environment Science Programme. 


Reference:

McGregor, H., Legge, S., Jones, M.E., and Johnson, C.N. (2015) Feral cats are better killers in open habitats, revealed by animal-borne video. PLoS ONE 10(8): e0133915. doi: 10.1371/journal.pone.0133915

Pedler, R.D., Brandle, R., Read, J.L., Southgate, R., Bird, P., and Moseby, K.E. (2016) Rabbit biocontrol and landscape-scale recovery of threatened desert mammals. Conservation Biology, 30(4), 774-782. 

Read, J., and Bowen, Z. (2001) Population dynamics, diet and aspects of the biology of feral cats and foxes in arid South Australia. Wildlife Research, 28(2), 195-203.

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