Professor Kirsty Park, Professor of Conservation Science, Faculty of Natural Sciences, University of Stirling
Professor Kirsty Park examines the role that bats may have played in the COVID-19 pandemic, and explains why it’s important that bats do not become a scapegoat in our efforts to control coronavirus. The virtual lecture is available to watch online, and a transcript is provided below.
Hello, my name is Kirsty Park, Professor of conservation science at the University of Stirling. Part of my research focus involves bats and, in particular, examining the impact of human activities on bat populations and what measures we can put in place that would be most effective in trying to safeguard their future. You don’t need me to tell you that anything related to covid-19 is a fast moving topic. There’s lots of new scientific research coming out all the time. What I’m presenting today is what’s known at the time of recording on 22nd May 2020, but obviously this may change in coming weeks or months. In putting together this presentation, I used information from a wide range of organizations and scientific papers. I’ve included these and some other useful sources on this slide.
Alongside the daily news concerning the tragic impacts that the pandemic is having on people and countries, you may have seen a lot of coverage on the origins of the covid-19 virus and how this got into the human population in the first place. Some of this coverage has focussed on speculation about which wildlife species the virus may have come from. But as we’ll see, there is much we don’t know. Some of the coverage has been really misleading and unhelpful, such as this headline from The Wall Street Journal on one very recently in The Australian. This very clearly pins the blame on bats. I’ll get onto the reason that this sort of reporting matters later on in the talk. There is also, unsurprisingly, a lot whole slew of information and calls for an inappropriate action that is circulating on social media, although lots of wildlife organizations are doing their best to counter these. The one shown here is a tweet from BirdLife International pointing out that killing bats will do nothing to stop the spread of COVID-19 and could make the situation worse. And then finally, there’s been recognition in the scientific literature, including this paper in Science, about huge negative implications this pandemic could have not only for humans but also for bats.
In this brief presentation, I’m going to address five questions on the role, if any, that bats may have in covid-19 and more pertinently, the role that humans have had in the pandemic and why it’s so important that bats do not become a scapegoat in our efforts to control this awful disease.
But before I get to these questions, just a few facts about bats. Listening to the coverage, you’d be forgiven for thinking there is only one species of bat in the world. In fact, they comprise over 20 percent of all mammals at around fourteen hundred species. The precise estimates for the number of species vary. They range in size from the bumblebee bat, that at two grams weighs less than a 1 pence piece, up to a giant golden crowned flying fox which comes in at just over 1 kg. They are found all over the world except at the poles, and many bat species are endangered. Of nearly thirteen hundred species assessed by the International Union for the Conservation of Nature, about 14 percent are threatened with extinction. We lack data on a further 16 percent, meaning that we don’t know what their population status is or whether it’s changing. The primary causes of declines in bat populations are habitat loss, overexploitation for food and persecution. Many humans fear bats largely because of myths and misinformation.
So let’s take a look at the first question, did covid-19 originate in bats? I’m going to start with a slightly different question about coronaviruses in general where do we find them? Figure A on the left hand side here shows the increase in our knowledge of which animals act as host to coronaviruses, and it’s done this by looking at the number of scientific publications over time. Publications citing bats as hosts are shown in red and non-bat hosts in blue. Figure B shows the proportion of different animals that are hosts to coronaviruses. So as you can see, many animals, including birds, ungulates and humans can be hosts, and bats make up a relatively small fraction of this. All of this is just to show that coronaviruses are found in a very wide range of animals and bats make up a relatively small portion of these hosts. It doesn’t, however, tell us about whether bats were host species to this particular virus, covid-19.
Very near the start of the pandemic, it was suggested that bats were the most likely source of the first human transmission, but in fact we don’t yet know if this is the case. Bats were initially thought to have been the source because of another similar looking coronavirus that had been found in one species of horseshoe bat in China in 2013. However, closer examination of the horseshoe bat virus suggests that it’s only distantly related to covid-19 and diverged from covid-19 about 40 to 70 years ago. The location for the first transmission is still thought to be a market in Wuhan in China, however, whilst this market was selling a wide range of species, reportedly no bats were on sale there.
There are several hypotheses about how covid-19 got into humans. And I should stress that at this point they are all hypotheses and there’s very little solid evidence for any of them. We do know that covid-19 came from an animal, but whether it was already pathogenic when it was transmitted to humans or whether it mutated within humans to become pathogenic is still unclear. Hypotheses include, firstly, that that was direct bat to human transmission or secondly, that there was direct transmission from pangolins, another group of species in which coronaviruses have been found. A third hypothesis, shown in this cartoon on the slide, is that there was an intermediate host, possibly a pangolin that became infected from bats and then went on to infect humans. Normally, bats and pangolins wouldn’t come into close contact, but this can happen in wildlife markets. So in summary, we don’t know which wildlife species was the original source of transmission to humans. But of course, this may become clearer in the future.
The second question is, can bats spread covid-19 and this is a much easier question to answer as it’s a clear no. Regardless of the viral origins, covid-19 is now a human disease and the risk of getting sick is from another person, not from wildlife. Whilst finding a wildlife source of the virus is important as it will help us track its evolution and origins in different species, the underlying backdrop to this pandemic is that it is humans that are responsible.
The ingredients have all been there for a long time. The catastrophic loss of natural habitats, and massive exploitation of, and trade in, wildlife. This can all help increase the interactions between wildlife and humans and increase the probability of a zoonotic disease being transmitted. The picture in the top right of the slide shows bags of pangolin scales seized by authorities in Nigeria. Pangolins are now considered the world’s most trafficked animal, even though all eight species are supposedly protected and two of those are critically endangered. They are also one of the groups of species which have been suggested as having a role in covid-19. Additionally, bringing different species together in close, confined spaces in wildlife markets, as we can see in this bottom row of photographs, means that viruses can be more easily transmitted to species they would not normally would have been exposed to. And then the ease with which humans may now move around the globe made it very easy for the virus to spread rapidly, with such awful consequences. So regardless of what might eventually be found out on the source or sources of the virus, humans are responsible for this pandemic and claims that this pandemic could not have been predicted are entirely without foundation. The emergence of a major zoonotic pandemic as a result of human activities has been predicted for many years.
So what about the consequences of covid-19 for bats? They’re not to blame for the pandemic, but they are certainly suffering the consequences. There have been reports from all over the world of bats being killed or dispersed from their roosts. Some politicians have called for mass culls. Other than the direct negative effect on bats, this kind of action has huge negative impacts on how bats are perceived more widely. This is really problematic for a group of species who are already in need of as much good PR as they can get.
The fourth question is why are bats important to us? Why does it matter if the pandemic impacts negatively on bat populations? I believe very firmly that we shouldn’t judge the worth of species just in terms of the benefits they can bring to humans, but in bats we can find a whole array of what are called these ecosystems services. I’m going to highlight just a few here. Firstly, we have pollination services, bats pollinate a wide diversity of crop species used by people. In the Neotropics they pollinate and disperse seeds of at least five hundred and fifty plant species. This includes things like cashews, mangoes, papaya, rubber plants, guava, passion.
Many bats eat fruits and as a consequence can be really good seed dispersers. It’s thought that the revegetation of Krakatoa following the eruption in 1883 was in large part aided by bats. So they’re likely to have a really important part to play in the restoration of other degraded landscapes in the tropics. About 70 percent of bats are insect eaters, and as such, they may offer valuable and free pest control services. One study estimated the overall contribution of bats to agriculture through the consumption of crop pests in the US alone at 3.7 billion US dollars. Maybe less initially appealing as a service to humans, bat guano is a really fantastic fertilizer. In some parts of the world, mining bat guano is hugely important for agriculture and a revenue generator to local communities. And then lastly, for this presentation at least, whilst many humans do fear bats, there are also a huge number that get great enjoyment from watching them. In the UK, the Bat Conservation Trust has over 10,000 members and there are over 80 local bat groups involved in monitoring bats and engaging the public in bat walks and talks. The photo here is taken from Bracken cave in Texas. This is a key maternity roost for Mexican free tailbacks with an estimated fifteen million bats roosting here. Their nightly emergence is a massive public attraction, with local businesses benefiting from the tourists that come to watch the bats.
So lastly, what does the future hold for bats and what can we do? Firstly, it’s really clear that we need to continue in our efforts to conserve what existing natural habitats is left and to restore and create new habitats. This isn’t just good for bats, but other wildlife as well, and all of the services they collectively provide for people. Secondly, we need to let the public and politicians know how important bats are and convince them to provide legal protection. Bats already enjoy some protection within European countries, for example, but throughout much of the rest of the world, they do not. In fact, in some countries they are classed as vermin. In the UK, our exit from the EU means we need to ensure that existing protections are not diluted. Finally, something we can all do is to check our facts. Avoid sharing scare stories and misinformation and then challenge others when they do so. If we can succeed in all this, then hopefully bats will have a future and humans will continue to enjoy the huge benefits they bring us. Thank you for listening.
Professor Kirsty Park, June 2020