Episode 155      32 min 49 sec
Endangered animal species: Captive breeding and genetic rescue

Geneticist Dr Andrew Weeks and animal behaviourist Dr Michael Magrath discuss diverse ways of dealing with threatened animal populations. Australia's Mountain Pygmy Possum is one such endangered species for which a combination of genetic and breeding solutions are being tried. With science host Dr Shane Huntington.

"As populations get smaller and smaller, those genetic problems manifest. Often you end up with what we call a genetic extinction vortex where there's no way out of it." -- Dr Andrew Weeks





           



Dr Andrew Weeks
Dr Andrew Weeks

Senior Research Fellow, Department of Genetics, University of Melbourne

Andrew is an ecological geneticist who specializes in applying genetic principles to the conservation of Australian wildlife. His current research interests are centered on translocations as a way of genetically rescuing populations from inbreeding, losses of genetic variation and the build up of slightly deleterious alleles. His interests are also in developing translocation strategies that aim to enhance a population’s ability to adapt under climate change. Andrew actively participates in several threatened species recovery teams in Australia, where he has developed research programs that look at hybridization of genetically differentiated populations as a way of reinvigorating the genetics of populations that have undergone large declines in numbers. In this vain, Andrew recently led a research team that undertook the first genetic rescue of a wild population in Australia. Andrew is developing similar programs for a number of different Australian threatened species.

Dr Michael Magrath
Dr Michael Magrath

Senior Scientist, Department of Wildlife Conservation and Science, Zoos Victoria.

Michael Magrath completed his undergraduate degree at the Australian National University, and then his PhD at the University of Melbourne in 1998. He subsequently held a number of research fellowships in Australia (ANU, University of Melbourne) and Europe (University of Groningen, Netherlands), before joining Zoos Victoria in 2010. He has also worked for the conservation organisation Birds Australia and the Natural History Unit at the Australian Broadcasting Corporation.

Michael has a background in behavioural and evolutionary ecology. Most of his previous research has involved wild bird populations, but he has also worked with mammals and invertebrates. He has experience with experimental design, statistical modelling and a range of research technologies, including molecular genotyping, energetic studies and remote monitoring systems.

Michael’s responsibilities as Senior Scientist at Zoos Victoria include the promotion of conservation and animal welfare research, particularly in relation to the zoo’s threatened species breeding programs.

To find out more about the conservation and research activities of Zoos Victoria and the conservation team visit www.zoo.org.au/Conservation.

Credits

Photos by Matt West courtesy of Zoos Victoria

Host: Dr Shane Huntington
Producers: Kelvin Param, Eric van Bemmel
Audio Engineer: Ben Loveridge
Episode Research: Dr Dyani Lewis
Voiceover: Dr Nerissa Hannink
Series Creators: Eric van Bemmel and Kelvin Param

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VOICEOVER
Welcome to Up Close, the research, opinion and analysis podcast from the University of Melbourne, Australia.

SHANE HUNTINGTON
I’m Shane Huntington.  Thanks for joining us. Increasing numbers of animal and plant species are coming under pressure the world over as their habitats face growing threats from climate-related and other environmental changes. In some cases, these changes are natural occurrences consistent with a dynamic planet whilst others are specifically due to human activity. Regardless of the cause, scientists are working to save many of the species that are in some way threatened. But the approaches taken in rescue efforts are far from uniform. Today on Up Close, we hear about two distinct ways of going about restoring species that are under threat.
As an example, we'll discuss the Mountain Pygmy Possum, an endangered animal species found in Australia. We're joined by Dr Andrew Weeks, Senior Research Fellow at the Department of Genetics and the Bio21 Molecular Science and Biotechnology Institute here at the University of Melbourne and Dr Michael Magrath, Senior Scientist for Wildlife Conservation and Science at Zoos Victoria. Welcome to Up Close Andrew and Michael.

ANDREW WEEKS
How are you going?

MICHAEL MAGRATH
Good morning.

SHANE HUNTINGTON
Michael, I might start with you. We often hear this idea that various species are actually endangered. How do we go about making that determination?

MICHAEL MAGRATH
Yeah. Well we know from recent evaluations done by the International Union for Conservation of Nature that a whole raft of species across many different groups of animals are indeed in danger and we're losing their numbers progressively and there's no real sign of that abating. I guess more specifically we assess whether a species is in trouble based on a number of factors. One of which is usually its small population size. So if we can get an indication that its numbers, for example, have fallen below a few thousand, also a declining trend in population. So if we can see that that population is not stable, it's not increasing; it's actually declining still.
Also our restricted distribution geographically is another indication that a species may be in trouble. A very restricted distribution means that species is perhaps more likely to suffer from some catastrophic event like fire, for example and in Australia, that's a particular issue. Also if we can identify that there are some key threatening processes that we know are actually acting on that population and depressing numbers and that might be, for example, introduced predators which are taking toll on the population.
If you've got a combination and usually in most cases it's going to be a combination of all of those factors, then that's going to give you a pretty clear indication that that species has become endangered and potentially critically endangered.

SHANE HUNTINGTON
Now when you talk about these species potentially dying out, how do you know that this isn't just a sort of natural, ecological process that has occurred, you know, many times before for many species across the globe? How do you make that determination that this is an unnatural scenario that's occurring?

MICHAEL MAGRATH
Well I guess you look toward whether humans have quite obviously had a significant effect on them. So in cases where you've got very restricted distribution, it's often quite clear that that restricted distribution is down to, say, deforestation, clearance of land for agricultural purposes and also, for example, these threats that I'm talking about that are introduced and clearly the result of human occupation in that area. Usually these sorts of things are fairly clear cut. The other with evolutionary extinctions, they most likely would occur over a protracted period of time. I mean there's no doubt species obviously do go extinct through the natural course of events. But I think the sort of pace that we see the changes in population sizes of these species is another indication that these are unnatural events.

SHANE HUNTINGTON
Andrew, you deal more with the genetics of the scenario and, as we know, there is such a wide variety of species out there. How do we ever go about determining which of that huge number is endangered and could we ever even contemplate protecting all of them?

ANDREW WEEKS
Look I think that's certainly a case in point that a lot of people struggle with. A classic instance of that is invertebrates which are generally the most diverse group of animals that we find on earth. You know, no-one knows a lot about those species and a lot of them do fall off every single day and a lot of them are due to human influence, a lot of them due to just natural causes. But we don't know a lot about them so we ignore them. It's more the, as we often call them, cute and cuddlies. You know people identify with them. So they themselves culturally want to help to try and save these animals. That's generally what dictates often whether things are getting saved or whether there's programmes that are established to help save these animals.

SHANE HUNTINGTON
Michael, Zoos Victoria being the conglomeration of the major zoos in the State of Victoria in the southern part of Australia, has a limited set of resources. How do you go about determining which species you should try and save and protect? I assume the number you can handle there is relatively small.

MICHAEL MAGRATH
Well this is absolutely right. Single species conservation, that's right, is a very costly exercise when you've got a captive breeding program associated with it. Zoos Victoria currently have around about 10 species that we have in captivity that are being held for conservation purposes through reintroduction programmes in some cases and insurance of population in others. Insurance means that you don't actually actively release animals to the wild at the time. But the idea is that you're keeping those animals safe with a plan to reintroduce them at a later date.
We've been through the exercise quite recently of determining what other species maybe should be on that list. I guess we effectively go through the same sorts of criteria that I mentioned before in terms of identifying which species are most at risk of extinction. We recently set a sort of period of time of about 10 years where we could try and identify terrestrial vertebrate species in Victoria that most at risk of extinction. We've identified another eight species or so. A few of these are the Leadbeaters Possum which is a very small possum species that has a very restricted distribution and also the Baw Baw Frog. We, again, look at issues around basically risk of extinction and it's one of our major objectives to try and ensure that no Victorian or south-east Australian species actually do become extinct within that time frame.
 
SHANE HUNTINGTON
Now you have in your zoos not just cute and cuddly animals but you have insects and reptiles and other things as well. Are there any insects that sit on the list of endangered species that you're trying to protect?

MICHAEL MAGRATH
There are. We've actually restricted in recent times to terrestrial vertebrate species. Nevertheless, we do have the Lord Howe Island Stick Insect in captivity. That' program's been running since 2003. That's a pretty remarkable program actually. The species was actually considered extinct from about 1930 after rats reached Lord Howe Island and were apparently responsible for eradicating these magnificent insects from the island. They're actually rather charismatic. They're quite large. Then they were not rediscovered again until 2000 when some people found them on this rock spire which is about 20 kilometres off the coast of Lord Howe Island. So that was obviously quite an exciting discovery and some of those individuals, a very small number were collected. A pair ended up at Melbourne Zoo and from that pair, after quite some concern that we weren't going to actually produce anything, that female actually produced quite a lot of young and we've established a captive breeding population there.
The hope is, of course, to get them back on to Lord Howe Island but the rats are still there and the rodents in general. Until they've been eradicated, really it's not an option. But certainly after we've looked at the vertebrate species, there's no question that we'd obviously like to be looking at invertebrates as well.

SHANE HUNTINGTON
Gentlemen, one of the examples we want to talk about today is that of the Mountain Pygmy Possum. So, Andrew, I might ask you if you could give us an idea of what this animal is, what it looks like and whereabouts in the world we find it.
 
ANDREW WEEKS
The Mountain Pygmy Possum is a small marsupial mammal. It's restricted to the alpine and sub-alpine zones of Australia which essentially restricts it to about 1600 metres to 2000 metres. That's considered the alpine zone in Australia. We have three mountain ranges in Australia where it's present. That basically represents its whole distribution within Australia. The three mountain ranges have varying numbers of Mountain Pygmy Possums on them. We have a northern zone which is Mt Kosciuszko in New South Wales which is a state of Australia. We have a central zone which is on the Bogong High Plains in Mt Higginbotham and Mt Loch in Victoria which is another state. We also have a southern population which is at Mt Buller which is just north of Melbourne in Victoria.
That represents the entire range of the Mountain Pygmy Possum. It's the extent member of its genus. It's the only one present and it was only actually rediscovered again in 1966. It was thought to be extinct. It had only been known from fossil records up until 1966 and then it was found on the mountain in the central range at Mt Higginbotham.

SHANE HUNTINGTON
Approximately how many do we think are left in the wild?

ANDREW WEEKS
Look in total, the population size is under 2000. The problem, as Michael suggested before, the reason we know that it's endangered is that in each of its ranges, it's declining in population size; in some of the areas a lot quicker than in other areas. For instance, the Mt Buller population in the southern zone in Victoria has reduced from about 300 animals down to 30 animals. So that population itself is critically endangered.

SHANE HUNTINGTON
This is Up Close coming to you form the University of Melbourne, Australia. I'm Shane Huntington and our guests today are Doctor Andrew Weeks and Doctor Michael Magrath and we're talking about dealing with endangered species, genetic rescue and captive breeding.
Andrew, in your particular case the response to population decline in the case of the Pygmy Possum is called genetic rescue. Can you describe what this process is about?

ANDREW WEEKS
As populations are threatened either through predation or through habitat destruction or through climate change and we get a reduction in numbers, that reduction in numbers has consequences at the genetic level. So as you reduce in population size, you tend to start breeding with closer relatives which leads to what we call inbreeding depression. That inbreeding depression manifests itself as a fitness consequence so you produce less progeny or those progeny don't survive as well.
As a result of the decline in those populations, so as they get smaller and smaller, those genetic problems manifest. Eventually, you know, and often you end up with what we call a genetic extinction vortex where there's no way out of it; there's no escape from it. That's where we try to intervene. We try to right those problems and that's what we term genetic rescue.

SHANE HUNTINGTON
Is there anything specific about the Mountain Pygmy Possum that makes it an ideal candidate for this compared to other species that you may come across?

ANDREW WEEKS
The Mountain Pygmy Possum breeds annually. It has about four young - up to four young per adult female. Its generation time is around two years. So it's all quite easy to start manipulating. A lot of other mammals, there a lot longer lived so you can't do these sort of things. So the Mountain Pygmy Possum are very easy to manipulate in that manner. The other thing is that we know that we can breed it in captivity which gives us insight into how we can do these things.

SHANE HUNTINGTON
How small can a population be for it to be genetically viable and how do you go about determining that size?

ANDREW WEEKS
A lot of different species go through population bottlenecks. They can get reduced down to a score of individuals; maybe as many or as few as 10 individuals. So one generation of that, while it is not great, it's not actually that bad. Genetically you're still retaining about 95 per cent of the variation that's present in the population. The problem is that when you have subsequent generations at that level. Every generation you start losing genetic variation and eventually you're in a situation where you could have lost 50, 60, 70 percent of your genetic variation. That's precisely what had happened the Mountain Pygmy Possum on the Mt Buller population in Victoria. That population crashed from 300 down to 30 individuals. But genetically we know through that period where it crashed which is from 1996 through to now, we know that the actual what we call the effective population size was only three. The effective population size is what is actually contributing genes to the next generation. So they're the ones that are mating and they're the ones that are - their progeny are surviving. That's what we term the effective population size which is different from your census population size.
So we know that that effective population size through those generations was only three and it rapidly lost genetic variation which resulted in it losing about 80 per cent of its genetic variation to what it was in 1996.

SHANE HUNTINGTON
When you're out in the field and you're determining this genetic variation for that particular population, how do you actually go about doing that?

ANDREW WEEKS
Yeah we use genetic markers we term then. They're generally very polymorphic markers meaning that there's many different copies of those markers within individuals and within populations. Those markers are termed generally microsatellite loci, they're nuclear. They're codominant. Codominant means you get one allele from your mother and one allele from your father. We score that so that we can track through populations; what's happening to that genetic variation.

SHANE HUNTINGTON
You mentioned two particular populations; one being on Mt Buller and one being on Mt Hotham. How closely related genetically are these populations and for how long have they been separated?

ANDREW WEEKS
Those populations both in the southern, the central and the northern areas of its distribution for the Mountain Pygmy Possum, they've essentially been isolated since the last glacial maxima in Australia which is about 10,000 years ago. From a genetic view point, it's a long time. That's potentially 10,000 generations of breeding.

SHANE HUNTINGTON
I can imagine this gives you quite an insight into the way a species evolves due to its environment. But these multiple environments are very similar. So do you see much difference between these populations over that period of 10,000 years?

ANDREW WEEKS
You can notice little differences between the individuals in each of the mountains. For instance, the animals on Mt Buller in the southern area are slightly smaller than the animals that you find on Mt Hotham in the central region. So there is that slight difference. But these animals are quite cryptic. The only way we can monitor them is by trapping them. They're nocturnal so we don't see them out and about during the day. So we don't know a lot about them, quite frankly. While we can monitor them and we can determine numbers within populations, we don't really know a lot about their basic biology. That is likely to have led to a lot of the problems that we now see in this species. One thing is this possum is restricted to what we call boulder fields. Boulder fields are large rock blocks that have been cut off three times just through the freezing and thawing of the rocks. They're like rivers on a mountain top; they extend right down the bottom to lower levels of the mountain. Unfortunately that's also what is prime habitat for ski resorts. So ski resorts use them for ski runs which means that they modify them and they have modified them in the past which generally hasn't been that great for Mountain Pygmy Possum.
To be truthful, it's not the fault of the ski resorts per se because a lot of the time they didn't know that those Mountain Pygmy Possum were there. So a lot of the habitat was destroyed or moved in that period. Now a lot of those ski resorts now have environmental plans which try and manage the Mountain Pygmy Possum on their mountain tops.

SHANE HUNTINGTON
Now you have the genetic information, you have the, I guess, the location of these two populations. How do you use those things together to help further the species and give that sort of mixing of genetic material that you suggested is so important.

ANDREW WEEKS
I mentioned that the Mountain Pygmy Possum population on Mt Buller had an effective population size of about three individuals for the last 15 years. Now an optimal effective population size is roundabout 500 to 1000 individuals. Now on Mt Hotham we know that there's a population there that exceeds 1000 individuals. In that area in the central region, there's about 1500 Mountain Pygmy Possums. So we know genetically they should be quite healthy and we've actually looked at them and we're seeing that genetically they look quite diverse. You don't have populations which are fragmented or have a reduced genetic variation or look like they're undergoing inbreeding. So that population is very healthy. So we can use that to help the Mt Buller population. Even though they've been separated for about 10,000 years, we know through some captive breeding that was undertaken at Zoos Victoria that they're able to cross and able to mate. So it provides us with an avenue to try and genetically rescue this population.

SHANE HUNTINGTON
I'm Shane Huntington and my guests today are Dr Andrew Weeks and Dr Michael Magrath. We're talking about dealing with endangered species, genetic rescue and captive breeding on Up Close, coming to you from the University of Melbourne Australia. Michael, I'd like to turn to you now. How do you go about establishing a captive breeding program in a zoo environment? What exactly does this mean?

MICHAEL MAGRATH
Well, I guess you want to have a fairly clear objective about what the program is really for. If you can identify if you've got this population in captivity and the main goal is for recovery in the wild through reintroduction, for example or, alternatively, perhaps to establish this insurance population, as I mentioned previously, to maintain these animals from the possibility of extinction in the wild. When it comes down to the practicalities, animals have to be collected from the wild usually. In which case, you want to try and capture as much of the genetic variation that does exist. As Andrew's alluded to, we would try and establish a population of somewhere 20 to 25 founding individuals which would capture 95 per cent of the genetic variation that exists.
Of course, it's actually very difficult with a small population not to lose that genetic variation through generations. For the same reasons that Andrew has already alluded to in the field where populations have become very small, the same sorts of things will happen in captivity. Where you lose genetic variation, you'll start to have inbreeding and you'll start to see the deleterious effects of this inbreeding through issues that you might see in low reproductive success, health problems of animals. But on top of this, you've also got the problem of adaptation to captivity to contend with. That's another significant genetic issue where animals actually become - under artificial selection if you like - unintentional selection for traits that actually mean that they do rather well in captivity. But in many cases, these are the sorts of traits that are not going to help them in the wild. For example, animals might become less fearful in general and less fearful of humans. While this is beneficial to them in captivity, they are less stressed; it's not going to be necessarily helpful in the wild. Indeed, if they lose their fear response and they're tossed back out in the wild again, they're going to be potentially at the mercy of a lot of predators.
We also have the issues with captivity, I guess, where animals are somewhat under artificial circumstances in terms of their mating systems. In the wild generally animals will have a choice somewhat of who they actually partner with. Whereas in captivity, what is generally done is animals are assigned a particular partner with the aim of trying to maintain as much of the genetic variation as possible. But the downside to that is, of course, this might not be a totally suitable partner for that individual. So you may have, for example, conflicts between their immune systems or something and you end up with offspring that are not of optimal quality. This is another thing that you certainly have to keep in mind with captive programmes and it's only quite recently that this has been appreciated. Certainly at Zoos Victoria, we're trying to integrate the opportunity for some degree of choice of partner wherever practical and that's certainly happening with the Mountain Pygmy Possum population where females get to assess a range of scents from different males that in the captive population prior to mating assignments. In that way, we hope anyway, that females are actually identifying males that are most compatible with themselves.
Then these animals get an opportunity to choose between several males; one of which is the one they selected on the basis of these scent trials. We're just waiting, really, on the results to try and identify whether indeed the females did prefer to mate with these males that they showed this original preference for. That's potentially quite a significant way forward, I guess, to try and maintain some of the quality of animals that you keep in captivity and that relates to their genetic quality.

SHANE HUNTINGTON
Michael, when you go about taking the animals in the first instance into the breeding programmes, how do you assess the impact that that has on the populations in the wild? Especially given the ones we're talking about are endangered and are very, very low numbers in some cases.

MICHAEL MAGRATH
It can be a controversial issue. Obviously we like to be in a position to take animals into captivity well before the numbers get to the point where removing 20, 25 individuals is going to create a significant decline in that population. Now that's not always possible of course because we often get a late call on this. Oh, we've only got 50 of these animals left in the wild. Now you have a tough decision to make then. If there's only 50 left and they're in decline, well they're probably not going to be in the wild for much longer. If they go extinct in the wild and you haven't got them in captivity, that's it; they're gone.
So quite recently, indeed, we've been faced with this challenge with the Orange-bellied Parrot which is a very distinctive Australian parrot that's critically endangered. There's only an estimated 30 or so birds left in the wild now. Those birds breed down in Tasmania which is an island off the south coast of Australia. The decision was taken to bring in 20 or so juveniles from this most recent breeding season back in 2010. This allowed us to set up a robust insurance population of these birds and, hopefully, provide a future for them. The plan is that we will grow this insurance population from this small number of animals and we'll be in a position to start reintroducing back into the wild within the next few years or so.

SHANE HUNTINGTON
Many of our listeners would be aware that there are some species that just don't seem to breed well in captivity. I guess the most known one is around the panda and they're have been very few successful breedings in captivity. How do you go about determining whether that will be the case? Do we have an understanding of why that is the case for some particular species?

MICHAEL MAGRATH
There are certainly some groups of animals that are going to be generally more difficult than others. That might be to do with their particular life history, characteristics. So say their long generation times or they have very specific conditions that they require for breeding. Some of that information might be available in advance from the wild. But often the case is with these endangered species is we don't necessarily know a lot about them in the wild. Obviously once we've decided that a captive intervention is required, then the first - ideally the first action is to bring a small number of animals in and try and learn as much as possible about them in captivity and develop those sort of husbandry techniques that are going to be necessary to get them breeding them in the wild. That can be quite challenging. But as a rule, well you've really just got to try with some of these species.

SHANE HUNTINGTON
Presumably, as you mentioned, you get to a point where you have some sort of release into the wild?

MICHAEL MAGRATH
Absolutely and I guess there are a range of factors that seem to affect the success of releases. To be honest, releases from captivity historically have not been very successful. I think some recent reviews estimated that only about 15 per cent of these release programmes from captivity have ended in success really. I mean there are many programmes that are still ongoing and you wouldn't say are unsuccessful yet or have failed. But nevertheless, there are really only a relatively small percentage of obvious successes.
Part of the issue is that you have to have sufficient number of animals. I mean if you're releasing only a small number, it can be very difficult really to establish a wild population. You just have - stochastic effects can affect that population. You also have inevitably limited genetic variation if there are small numbers that are released, other issues; the quality of the animals. As I've discussed some of the ways in which you try and maintain the genetic quality and the wild behaviours of animals in captivity. If you don't do that, it's likely that that's going to be unsuccessful.
The habitat you release into itself is obviously critically important. Unless you've really tackled the threat that led to the original decline in the species in its wild range, then it's very likely that any sort of reintroduction will indeed be unsuccessful because the same issues that led to the wild population declining and, in many cases, becoming extinct will still be operating.
You also have to ideally do some modelling in advance to try and determine, based on the breeding rates that you can expect and the survival of those animals, what sort of numbers that you should be seeing out there. What sort of increases you expect to see over a period of time if you are, indeed, going to result in successful recovery. Experimentation as well; well planned experiments for reintroductions will always help to refine and improve the procedures. So ideally where you have a controlled experiment, perhaps you might, for example, reintroduce animals at several different times of the year if you don't really know when might be best for a reintroduction.

SHANE HUNTINGTON
Michael, when we talk about releasing animals in the wild, you did hint on the idea that some of them become domesticated. How do you know when an animal is actually ready to be released at a particular time?

MICHAEL MAGRATH
Well in some cases, animals require pre-release conditioning prior to reintroduction. This may involve just becoming familiar with the sort of wild foods that they're going to encounter. Food plants from the actual release site can be brought into captivity and those animals can be provided with them for a period of time prior to release. Then there's also conditioning to become familiar with the sorts of alarm calls from their conspecifics, from their own species in that location if they exist there, that will allow them to be aware of predators in the area for example. Also providing a sort of adverse situation for them so they'll become to associate that alarm call with the image of the predators and also with a sort of scare that they'll get. These are the sorts of things to train animals to become more aware, I guess, of their wild environment.
There's also another rather interesting example with the Northern Quoll. The Northern Quoll has dramatically reduced in numbers in recent times. One of the main issues there apparently is through predation by these animals on Cane Toads. Now the Cane Toads are quite toxic to a lot of Australian native fauna and the Quolls have been eating these Cane Toads and dying. One of the approaches is to actually train these Quolls prior to release to avoid Toads as prey. To do this, they've been presenting them with very small toads, very young toads that they'll eat and become a little bit sick on and even presenting them with a chemical that makes the Quoll a little bit nauseous. So it associates the flavour of the Toad and the smell of the Toad with feeling ill. So they avoid them. I think they've gone to the point of making sausages now out of Cane Toads, presenting them and even once they've eaten the sausage and become ill through the chemical, they can still detect the smell of the Cane Toad and recognise the Cane Toad as a problem and something to avoid as far as eating. There might be the possibility of aerial drops of Cane Toad sausages, for example, beyond the Cane Toad front where the Cane Toads are moving through northern Australia before they get into these unaffected areas and hopefully save a lot of these Australian native carnivores.

ANDREW WEEKS
I guess if I could just add to that. One of the other things that I guess is being undertaking a lot more is releasing these captive bred animals into open range parks which are totally fenced so they prevent the main predator which is the fox in Australia. They prevent that predator and feral cats and dogs from accessing those animals. But they do train them to be acute to a lot more different things that they would be experiencing out in the wild. They still have some predation threats such as birds; birds of prey which can come down and collect them. But generally they start to live in a more open environment and get a lot of the experience that they need to survive out in the wild.

SHANE HUNTINGTON
Andrew, just finally with regards the Pygmy Possum, where are we at the moment and how sort of far away do you think we are from sort of having to pull back on some of these interventions to secure the population?

ANDREW WEEKS
We've got two issues with the Mountain Pygmy Possum. The first is the genetic issue. We have to make it more genetically robust. The second issue is that we need to get numbers back onto the mountain. We're approaching that in two different sort of stages. Getting the numbers up is what we're actually doing at Zoos Victoria. They're trying to build up a population that can be released back onto the mountain. But the genetic issues are something that we need to address right now and unfortunately Captive Breeding Program is not in a position to be able to do that right now. They're still learning a lot in the program and they're only now just starting to get the numbers up so that we can think about releases in another couple of years.
So what we've actually undertaken is what we call a wild translocation. So we've taken individuals from Mt Hotham and moved them over to Mt Buller. The sole purpose of that is to genetically rescue and restore genetic variation in that population. It's a first for Australia, it's the first time that it's ever been undertaken for that purpose in Australia. We did it last October in 2010 and we're more than likely going to move more individuals again in October 2011. We're monitoring that at the genetic level to make sure that it is working and that we are able to restore the genetics of that population. That's exactly what we hope to see over the coming years. If that's the case, it will be in a very good position to start having releases of individuals from the Captive Breeding Program and see the recovery of this population. We expect that that might occur over the next sort of five years or so.
In terms of the threats on the mountain top, habitat is starting to be restored; predation from foxes and feral cats and dogs has been brought under control. So, yeah, as I said, hopefully in five years' time if you ask me that same question, I'll be able to reply to you that we have a population size in excess of a hundred on that mountain.

SHANE HUNTINGTON
Let's look forward to 2016 then for some good results.

ANDREW WEEKS
No worries.

SHANE HUNTINGTON
Dr Andrew Weeks from the University of Melbourne and Dr Michael Magrath from Zoos Victoria. Thank you for being our guests on Up Close today and giving us a much better understanding of dealing with endangered species.

ANDREW WEEKS
Thanks Shane.

MICHAEL MAGRATH
It's a pleasure.

SHANE HUNTINGTON
Relevant links, a full transcript and more info on this episode can be found at our website at upclose.unimelb.edu.au. Up Close is a production of the University of Melbourne, Australia. This episode was recorded on 5 August 2011. Our producers for this episode were Kelvin Param and Eric van Bemmel. Audio engineering by Ben Loveridge. Background research by Dyani Lewis. Up Close is created by Eric van Bemmel and Kelvin Param. I'm Shane Huntington, until next time, good bye.

VOICEOVER
You've been listening to Up Close.  For more information visit upclose.unimelb.edu.au.  Copyright 2011, the University of Melbourne.


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