What has veterinary medicine got to do with conservation?

Part 2: Avoiding the Fate of the Dodo: the Importance of Disease Surveillance

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“In conservation, disease is like the fourth horseman of the apocalypse. For a bird population to grow, for example, we know they need safe nest sites, reliable food sources and freedom from predation. But that’s not enough. If you have a small population of a threatened species, the sudden onset of disease, perhaps brought in from somewhere else, can very quickly have a catastrophic effect.”  

Andrew Greenwood, WVI co-founder and avian veterinary specialist.

Saving the echo parakeet ‍

The dodo – that iconic symbol of anthropogenically driven extinction – only ever lived on Mauritius. It became extinct around 350 years ago, shortly after humans discovered the island. In recent decades, several other bird species unique to Mauritius have come perilously close to extinction, including the echo parakeet. In the late 1970s there were believed to be less than 20 surviving in the wild, making it the world’s rarest parrot. Today their numbers are estimated to be over 800 and growing. Concerted efforts to restore habitat to ensure food and nesting sites complemented a carefully managed captive-breeding programme. As a result, the echo parakeet has had its IUCN status ‘downlisted’ twice this century, first from Critically Endangered to Endangered in 2007, and then to Vulnerable in 2019.

But the parakeet’s recovery was gravely threatened by a serious virus; Psittacine Beak and Feather Disease (PBFD), introduced to the island by invasive rose-ringed or ring-necked parakeets. WVI co-founder, Andrew Greenwood, worked in partnership with the Mauritian Wildlife Foundation (MWF) and the Durrell Institute of Conservation and Ecology (DICE) for over twenty years, and was able to guide the local team though a potentially catastrophic outbreak of the disease in the 2000s, advising on interventions in the field to help reduce exposure to the virus, which in the long term have enabled the parakeet population to adapt and live with it.

Andrew helped introduce comprehensive disease testing, with staff being trained to collect and analyse samples correctly, and returned at regular intervals to help make sure expertise was not lost through inevitable staff turnover. In the words of MWF Director, Dr Vikash Tatayah:

‘Had Andrew not sorted out our captive breeding standards and management in the wild, guided us through PBFD and provided us with his wisdom, we would not have got here!’

While the MWF team are now very much self-sufficient, Andrew remains on hand should any veterinary issues arise, and the partnership model that evolved from their collaboration is one that characterises much of WVI’s work today.

The continuing importance of disease surveillance

In 2024, disease surveillance, testing and mitigation matters globally more than ever. Healthy, biodiverse ecosystems naturally regulate disease. Today, population growth, the spread of settlements and increasing numbers of livestock mean habitat is inevitably being reduced and degraded, eroding the natural barrier between people and wild animals. As a result, ecosystems are weakened, with unregulated hunting and the illegal wildlife trade exacerbating the problem. Different species are coming into every closer contact and the chances for disease to jump between hosts are increasing. Canine distemper virus (CDV) is one example, with the pathogen able to spread from domestic dogs to wild carnivores.

The emergence of canine distemper virus as a global threat to tigers

Working in partnership with the Wildlife Conservation Society (WCS) in the 2000s and 2010s, WVI co-founder, the late DrJohn Lewis, played an instrumental role in making sure biomedical samples were correctly and systematically collected from wild Amur tigers during trapping for radio collaring, embedding best practice and transferring vital practical skills to those working in the field. Comparison of stored samples later revealed CDV as an emerging disease in the big cats. The disease has since been detected in tigers in Sumatra (2021), India (2022) and Nepal (2023), suggesting it is becoming endemic throughout the tiger’s range.

While WCS has since created its own internal Wildlife Health Unit, new partnerships have evolved between WVI and organisations in other tiger range countries, most notably in Indonesia initially, and most recently in Nepal. Having supported local wildlife vet, Dr Amir Sadaula of Nepal’s National Trust for Nature Conservation (NTNC) to enable him to remain in his post at the country’s first and only wildlife hospital during the Covid pandemic, WVI was then able to bring him to the UK for essential training in anaesthesia and imaging. WVI Veterinary Partner Dr Jess Bodgener is now working in partnership with Amir and a number of Nepalese agencies to investigate the prevalence of CDV in leopards[1] and to consider how this might affect their behaviour, which could in turn lead to an increase in their chances of coming into conflict with humans.

The initial research suggests that leopards in Nepal are considerably more likely to be infected by canine distemper virus than tigers. The team examining the biomedical samples from the big cats also reviewed diet studies for both species and found that all the leopard diet studies found evidence of domestic dog consumption, while none of the tiger diet studies did, suggesting a likely transmission route from free ranging domestic dogs to leopards. A better understanding of the disease processes involved will be able to inform policies around the release of animals recovered from illness, or who have been involved in conflict situations.

Disease surveillance in a wider context

While disease might be typically thought to involve pathogens and infection, in its broadest definition it refers to any impediment to the normal functioning of the body and could be the result of injury or, in the case of sea turtles for example, the ingestion of plastics. WVI is in the process of establishing a new partnership with the government of Ghana to look at why a particularly high number of sea turtles are washing up on beaches near the capital, Accra.

This developing partnership has grown out of work that WVI Veterinary Partner Matthew Rendle RVN has been working with West African Primate Conservation Action (WAPCA), helping build a healthy reserve population of Endangered white-naped mangabeys, with a view to possible release back into a community managed forest. Building relationships founded on mutual trust and respect, where the two-way exchange of knowledge and understanding of local circumstances is key, is central to how WVI engages with in-country conservation organisations, and has led to involvement in this new turtle initiative.

What is happening to Ghana’s sea turtles?

While visiting Ghana to support WAPCA over the last four years, Matthew has become aware of an alarming number of sea turtles washing up dead or dying on beaches just south of the capital, Accra. In just one day last year, he was shocked to find 12 dead turtles, representing a variety of species and in varying states of decay, along a short stretch of beach.

Matthew has been discussing the problem with head of the Ghanaian government’s Wildlife Division, vet Dr Meyir Ziekah, and Mr Dickson Agyeman, Head of the Wetlands Department of the Ghanaian Forestry Division, as well as with Accra Zoo’s Dr Samuel Asumah – one of Ghana’s very few practising wildlife vets- whom WVI recently brought to the UK for CPD training. There is a pressing need to find out more about what is happening to these turtles and consider what can be done to mitigate the threats they are encountering.

The investigation into what is causing such high turtle mortality in regions recognised as globally important wetlands – the Songor Ramsar site and UNESCO Biosphere Reserve, and the Keta Lagoon Complex Ramsar site – will require time and needs to begin with comprehensive recording of turtle strandings. This will involve teaching local teams how and what to record, and what to do when they find a turtle alive. In the longer term, and once the causes of these strandings are better understood, the aim is to establish a small rehabilitation centre, where sick or injured turtles can be given the necessary veterinary care before being released back into the ocean. WVI has a well-established reputation for training turtle conservationists, rehabilitators and vets in Spain and Greece, and Matthew is hopeful that it will soon be possible to transfer vital knowledge and skills to those working with turtles in Ghana.

Avoiding the fate of the dodo

The recovery of the echo parakeet on Mauritius is uplifting, and it’s far from the only success story on the islands. The Mauritius kestrel has made a similarly impressive recovery, from just four wild birds fifty years ago to over 300 today, while the pink pigeon has also been brought back from the brink of extinction. Like the echo parakeet, the pigeon's conservation status has now been downlisted to ‘ Vulnerable’. But it’s about so much more than just the numbers. MWF’s excellent work on the ground has resulted in a very comprehensive – even unrivalled - database of wild individuals, covering many endangered species. That endeavour, along with the high quality of the science involved and the professional training of conservationists on Mauritius over the years, has gone on to inform species recovery and rewilding programmes around the globe. Nevertheless, disease surveillance is still key, and WVI remains on hand to advise if needed on MWF’s ongoing work into the investigation and management of complex disease problems and risks which are always present and can affect any of these recovering species at any time, just as they can impact any species conservation initiative around the globe.

At first glance, disease surveillance may not seem like the most dynamic or exciting aspect of species conservation, but doing it properly is key to the long term success of efforts to save threatened species from extinction.

[1] Bodgener, J.,Sadaula, A., Thapa, P. J., Shrestha, B. K., Gairhe, K. P., Subedi, S., & M. Gilbert. (2023). Canine distemper virus in tigers (Panthera tigris)and leopards (P. pardus) in Nepal. Pathogens, 12(2),203. doi:10.3390/pathogens12020203 

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