Josh Donlan is the founding director of Advanced Conservation Strategies, a non-profit organisation that aims to promote novel solutions and ventures, based on solid science, to solve conservation problems. From 2002 to 2006 he served as Chief Scientist on Project Isabela in the Galapagos islands, a bold conservation intervention to rid islands of feral goats that were decimating the natural vegetation. Hari Sridhar spoke to Josh Donlan to find out more about Project Isabela and the animal rights and welfare issues surrounding invasive species eradication on islands.

Hari Sridhar: To begin, can you tell the reader what invasive species are and why they are particularly problematic on islands?

Josh Donlan: Before worrying about whether a species is invasive – which necessarily means it is highly interactive with other species — we need to first answer the question is it native or exotic. Defining non-native species can often be not straightforward and somewhat complex depending on your view of ecological history. In some cases, it is very clear that a species is non-native, such as rats and cats on islands, because very few islands have an ecological history of mammals. In other areas, especially in continental areas, it can be more complicated or grey. Take horses in North America. Most people view horses in North America as non-native, but actually, horses evolved in North America and then radiated out and later went extinct in North America. So, the horses that are in North America today are very similar genetically, and probably ecologically, to the horses that were present here 10,000 years ago. Therefore, whether or not you consider horses ‘non-native’ depends on what your baseline is. On islands, more often than not, it is easier to tell whether a species is non-native because their ecological histories are clearer. For me the first step is always this, to see whether a species is native or not, independent of its impact. Whether it is invasive or not, and what we do about that, is the next step.

HS: Please tell us a little about the history of “Project Isabela” and how you got involved in it.

JD: The history of this project is quite long. It began in the late 1990s when a group of experts got together for a workshop in Galapagos to brainstorm on what to do about feral goats. These goats had been on the Galapagos archipelago for a long time – over 100 years – and had recently moved from southern Isabela into northern Isabela island and were having significant impacts on the ecosystem there. At that time, the largest island from which goats had been removed was about 17,000 hectares. Isabela is over 500,000 hectares. If you had asked the average conservationist working on islands and invasive species at that time, he would have probably said it would be impossible to remove goats from such a large area, given the current best practices and success to-date for invasive species management on islands. The result of that workshop was that the participants concluded it might be possible to do this using new techniques largely developed in New Zealand and Australia. Next began a long process of fund raising, strategy development, and capacity-building to launch Project Isabela, whose main goal was to first remove goats from Santiago island, which was around 60,000 hectares, and then moving on to Isabela island. My role was of Chief Scientist, working with the practitioners to collect all sorts of data on the eradication process itself — information that could be used to develop methodologies to make eradications more cost effective. We also collected data to understand, from a biodiversity perspective, both the impacts and the benefits of removing goats from these islands. Project Isabela was successful and a game-changer for the eradication of feral goats and other invasive herbivores from islands. Today, these mega eradications are increasingly common.

HS: What was the problem with the goats?

JD: The goats were clearly having major direct and indirect impacts on the ecosystem. The Galapagos islands have no history of native mammalian herbivores. The goats, through their grazing and browsing, were changing plant community structure and in some cases leading to local extinctions of plant species they preferred to feed on. These direct impacts, in turn, had indirect impacts such as altering hydrology patterns and reducing numbers of tortoises, which are the main herbivores and a keystone species on the island. After the goats were removed, we have been able to document the positive impacts. For example, the Galapagos rail (Laterallus spilonota), which is endemic to the Galapagos, was thought to be extinct on Santiago island due to the impacts from goats and pigs. Through the use of surveys using an audio playback system, we were able to repeat rail surveys conducted in the mid-1980s. Estimated densities had increased by over an order of magnitude, largely due to vegetation recovery. The benefits of invasive species eradication on the Galapagos Islands have been documented on other islands for other species as well.

HS: Right from the beginning, was it clear that removing goats was the only way to deal with this problem? Were other ways of tackling the problem considered?

JD: Certainly other possibilities were discussed, such as control programmes. But it was felt that, over the long term the best strategy and certainly the most cost-effective and low-risk strategy was complete removal. Having said that, there still are, as far as I am aware, small numbers of goats that are connected with the local communities on southern Isabela island. So the long-term strategy is to have ‘Judas goats’ out on the island as a biosecurity measure to help manage the risk of reintroduction or reinvasion.

HS: What are ‘Judas goats’?

JD: ‘Judas goats’ were originally developed in New Zealand. Project Isabela took Judas goats to the next level, in terms of developing it as a conservation tool for invasive species management. With the proper resources, it turns out it is relatively easy to remove 90% of a feral population, but it tends to be really expensive and really hard to remove the last animals. To give you a real-world example – in Santiago island, around 79000 goats were removed from the island in 4.5 years spending USD 6.1 million. Removing the last 100 goats cost USD 2 million and took almost two years! The last animals are extremely difficult and expensive to remove. Judas goats are a technique to deal with this problem. You capture live goats, radio-collar them and put them out on the landscape to take advantage of the social biology of goats, i.e. other goats are drawn to the collared goat and vice versa. You go find your Judas goats with a helicopter and remove all the goats around them. In our case, we had around 400 Judas goats all across the island, at the same time for a year, to remove the last animals.

HS: Was there opposition of any kind to your proposal to remove the goats?

JD: It was definitely controversial. Unlike eradication projects in the US, Europe and New Zealand, the controversy wasn’t so much from an animal rights or animal welfare perspective. It was mainly opposition from people who were using the goats, e.g. some fishermen claimed that they used the goats on fishing camps, occasionally hunting them. So there was some community opposition with respect to access and use. It turns out that these benefits are probably relatively minor compared to, what could be argued were, the societal benefits of goat removal. But it certainly was controversial, and it is complex on Galapagos because there is a long history of controversy and conflict between the communities and the national parks, mostly around fishing permits. This conflict tends to impact all sorts management actions by the National Park. So Project Isabela became part of the larger controversy that is long-standing between communities and government agencies that are managing the park.

HS: But wasn’t there any opposition on grounds of animal rights and welfare?

JD: No, there wasn’t. It is somewhat surprising given the fact that it was the largest eradication project in the world at that time and still is one of the largest eradication projects. But we did not experience any opposition from animal rights or welfare groups, unlike other invasive species eradication projects I have been part of in the US, which have often gone to court.

HS: For a naïve observer this might seem like a somewhat strange situation – killing thousands of a ‘semi-wild’ species to safeguard another wild species. What would you say to such an observer?

JD: That’s one of the main questions that comes up around this fairly aggressive conservation action of invasive species eradication. My view largely comes down to values and what kind of world do you want to live in.

Do you want to live in a world that’s dominated by a few species that are the same everywhere you go – rats and dandelions and goats – or do you want to live in a world where there’s diversity and different species in different places? If you look at the big picture, we are seeing this global homogenisation of biodiversity – if I go to California or the Mediterranean or the west coast of Australia I see the exact same weed species. It is pretty striking. And more so on islands. Islands have been disproportionately impacted by invasive species for a variety of reasons. So the question really is what do we value more. On an island, do we value a rat that exists in lots and lots of places, or a bird species that’s on the verge of going extinct, that breeds only on three or four islands in the world? In my view that’s what often justifies this aggressive action of invasive species eradication.

HS: You mention that in other eradication programmes in the US and Australia/New Zealand there has been opposition, even court battles, on animal rights/ welfare grounds. Can you tell us more about that?

JD: You can probably divide the opposition into two different issues – one is a straightforward animal rights and welfare issue. Rats have rights and they deserve to exist on this island whether they are native or not, and whether they are having species and ecosystem impacts or not. These groups are just ethically against killing any animal which is, in my view, problematic since animals die (and kill) all the time. The other issue is around safety. For example, the best practice for removing rodents are toxicants – rodenticides which are often broadcast over an entire island by helicopter. There can be short-term impacts on non-target species. And, in situations like New Zealand, there are often long-term programmes that are using toxicants. So there have been concerns and oppositions around potential impacts beyond the target species. This is a justified concern. And in fact, a lot of effort is being spent on developing practices that are as safe as possible and that mitigate any impacts on non-target impacts. Also, educating the public on not only on the short term impacts but also the long-term conservation benefit is important. It’s a pretty complicated situation and a challenge to communicate that to the public and to the policy makers. In my view, invasive species eradication should be viewed through a cost-benefit perspective. Often, the benefits outweigh the costs.

HS: Does opposition along animal rights/welfare lines usually come from organisations or from the local people? 

JD: From both. Depends on the context of the species that you are eradicating and the techniques you are using. I find that, as long as we are safely eradicating a species and we frame it in the big picture, we often end up convincing people of the value of invasive species eradication. I’ll give you an example. There is an island called Guadalupe where Layson albatrosses (Phoebastria immutabilis) were being decimated by feral cats. A female albatross, with a chick on the nest, would go off on a feeding trip–flying tens of thousands of kilometres up to Alaska-to find food for its chick. It returns, feeds it chick, and makes the long journey again. Then, one day, the chick is killed by a feral cat. In such a situation, who is one to say that the cat has priority over the albatross? That’s why the animal rights argument is problematic, because it’s relative. In my view it is easier to make the argument that Layson albatrosses are more important than cats, in this case, because cats are more widespread. So I think the real debate, the more useful debate, should be about whether we are conducting these eradications in a safe way, and whether the benefits outweigh the costs. However, you are never going to convince everybody.

HS: I notice you have been involved in eradications of many different invasive animals – cats, rats, pigs, donkeys, beavers, goats etc. Does eradication become more of a challenge in the case of animals that humans share a strong bond with? For example, is rat eradication easier than cat eradication?

JD: On average I would say yes. You don’t often see people rallying in the defence of rats – although it has happened in the US – in comparison to cats, which people keep as pets. And the island conservation community is finding itself having to deal with such issues more and more. As we have got better and better at removing invasive species from islands, we are taking on larger and larger islands. What this means is that we are now dealing with islands that are human inhabited. This adds a complex social layer – whether its pets, livestock, or a perceived or real risk to humans. Practitioners are having to deal with this human angle more and more, and are starting to do the social science and education to engage stakeholders, both on and away from the island, in order to get support for the eradication. This is all the more important in a place like India where you have a very different culture around animals and wide prevalence of vegetarianism. So we really need to tailor our strategy based on the species and the place.

HS: Does it also matter whether the invasive species is wild or domestic? For example, the Chital (Axis axis) is considered invasive in the Andaman islands in India, but it is also found wild in forests in mainland India.

JD: My view is that it raises a major challenge in communication. The general public doesn’t necessarily appreciate ecological history or whether a species is native or exotic. In India, people have heard about and seen wild Chital (Axix axis) in forests on the Indian mainland but they might not be aware that they never existed on Andaman island and might be bad for the ecosystem. I think it definitely raises a lot of social challenges, as well as policy challenges. We are increasingly seeing situations like this where practitioners are trying to navigate those challenges.

HS: Do you also take into consideration positive impacts that invasive species might have on the ecosystem?

JD: In my view, it all comes down to ecological history. If you take any typical oceanic island, chances are it has never had a native mammal. So it’s hard to make an argument that a non-native mammal will be having positive impacts on the ecosystem, whether it’s in terms of species interactions, biodiversity, or some ecosystem service. But there are exceptions. For example, there is a small Hawaiian island where an endemic goose called the Nene (Branta sandvicensis) went extinct. Now, conservation practitioners are using tortoises as an ecological substitute, in an experimental way to see if the tortoises can browse on the vegetation like the Nene did. So that’s a situation where they are hypothesising that the tortoise –a non-native species – can act as an ecological proxy for the extinct Nene and that it will have a “positive impact” on the ecosystem. A similar situation comes up with goat eradication. There are some striking examples where practitioners have removed goats from islands and you see this explosion of weedy plants. So now, in the last decade, practitioners have started to take more of an ecosystem approach to invasive species eradication by conducting invasive plant control operations at the same time as the goat eradication.

HS: Now, in the programmes you are involved in, do you reach out to animal rights groups and other stakeholders right from the beginning? Do you also run outreach programmes to explain to people why you are doing what you are doing?

JD: Certainly best practices have improved over the past decade or so. Nowadays, when conservation groups are planning eradication programmes one of the things they do first is engage groups that might have issues with the eradication or oppose the project. What a lot of people don’t realise is that, in eradication programmes, the actual eradication – getting rid of rodents is a perfect example –might take one day with a helicopter. But in order to drop poison from a helicopter on one day, you are probably going to spend a year or two planning, getting permits, working with policy-makers, and getting all the stakeholders on board. So the planning and getting permits is usually the bulk of the work, compared to the actual on-the-ground eradication. And that’s becoming increasingly the case because practitioners are starting to tackle these very complex eradications. Andaman Islands are a good example. The Andaman Islands are amazingly complex, not only because of social, political, and cultural factors, but also because there is a big city on the island. Not to mention, indigenous groups living in isolation nearby. This is not to say that the removal of invasive species would be easy, but the big challenge is the people. It is a people problem.

HS: Since you have visited Andaman and seen : Since you have visited Andaman and seen the problem first-hand, what is your view on the Chital issue? Do you think that the solution there too lies in eradication?

 JD: From my limited experience in my trip over there, my view is, at the minimum, there is limited evidence suggesting that the species is having a negative impact on the ecosystem. We know that it’s non-native. And that there is a whole suite of other non-native species that are likely having an impact. So the next obvious step is to commission a feasibility study that will objectively look at the available data – scientific as well as social – and try to make a roadmap for a cost-benefit analysis to explore a whole portfolio of potential management interventions, of which eradication will only be one. I think it is probably premature to say we should eradicate them, without doing the homework and looking at each of the management interventions that are possible.

The purpose of my trip there was to help start this long process, and try to educate the stakeholders on what is possible. Technically, based on what has been done elsewhere, removing Chital from the Andaman islands is probably technically feasible. But whether the benefits outweigh the costs, and whether it is feasible from a policy and social perspective are unanswered questions.

HS: I have one final question. The motivation to remove invasive species is because we see them as man-made changes. What we are trying to do is move the system back to what we see as more natural or pristine. But one could argue that humans today are part of the planet’s natural system and eradication is just replacing one human-induced change with another. How do you decide where to draw the line? How far back in history does one go to consider something natural?

JD: Obviously, that’s a very complex question. In terms of how we decide, I guess my initial reaction would be that it is above my pay grade! I don’t make that decision. But, in general, I think it comes back to what I said earlier – it is asking what kind of world we want to live in. What is natural and unnatural is a loaded question, and we can ar
gue about it forever. Instead, I would ask myself, or the people I am talking to, about these complex issues – what type of world do you want to live in? Do you want to live in a world filled with rats and dandelions, or do you want to live in a world where there are all these cool endemic lizards on Andaman islands, even if you may never see them? Does that add value to your life? We know we are increasingly living in a world of rats and dandelions. Are these aggressive, and often controversial, conservation actions justified in order to maintain some of the biodiversity around the world? In my view, it is. As long as we can do it safely. And, as long as we are transparent about it. I think that’s a simpler view than trying to say what is natural and what is unnatural. And like I said at the beginning, ecological history can provide a kind of a roadmap to where we want to go.

Hari Sridhar is a postdoctoral fellow at Indian Institute of Science, Bangalore, harisridhar1982@gmail.com.

Illustrations: Smitha Shivaswamy

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