SEASONAL FOCUS

Destruction of nature is creating the perfect conditions for the next pandemic

Billy Flynn wonders if urban living is a threat to the wild species around us but also, could they be a threat to us?

If you live in a city, whatever the size, it is likely that at some stage you’ve taken pleasure – or maybe even delight – in some of the wild species that share this built space with you and the other humans. Finding out what wildlife dwells in the midst of the streets and buildings is one of the things that natural history enthusiasts never seem to tire of. Over years of attending (and occasionally leading) IWT events in Dublin, it was heartening to see the thrill that participants took from finding otter scats near the River Dodder or birds that travel thousands of kilometres to over-winter at a site within the busiest part of the city centre. I have often been asked what it is about certain species that allows them to thrive in these least natural of places when others cannot. A corollary question is: why do they live here? Another question that I have often considered, when looking at our litter, waste and bright street-lighting is, does city living harm the wild species that dwell among us? One question that never occurred to me was whether these new neighbours could be harmful to us. A recent paper in Nature (August, 2020) has examined all these questions with the widest-ranging study of its kind so far and the answers give cause for concern. The study looked at nearly 7,000 ecological assemblages and 376 species and how our

urbanisation has affected them. The results showed that the advances of the urban area and farmland into the wilds disproportionately affects larger species. This leaves the smaller and more adaptable species more likely to survive and to be the ones sharing our built-up spaces. Another key finding is that these species are far more likely to be the ones carrying zoonotic pathogens (diseases-causing organisms that can ‘jump’ from animal to human hosts). The degree to which this occurs is highly significant. Known wildlife hosts of human-shared pathogens and parasites overall

were shown to comprise a greater proportion of local species richness (18–72% higher) and total abundance (21–144% higher) in sites under substantial human use (secondary, agricultural and urban ecosystems) compared with nearby undisturbed habitats. How this effect was found in different animal groups varied but was strongest in rodent, bat and passerine (perching) bird host species. These are the ones that we must focus on. An interesting (and disturbing) aspect of the study was that conversion of wild areas to farmland and not just urbanisation is as significant

A lone heron on a canal bank with a group of swans in the canal, Portobello Harbour, Royal Canal, Dublin, Ireland.

a driving factor in encouraging the incidence of zoonotic disease in wild species.

The study further shows that mammal species that harbour more pathogens overall (either human shared or non human shared) are more likely to occur in human-managed ecosystems. So, the mammal species that can carry these diseases are also better adapted to put up with human disturbance and more likely to live among us. Across all these thousands of cases, it is clear that how we are altering or removing wild places is increasing the likelihood that we will come in contact with these diseases. In light of the ongoing Covid-19 pandemic, this is chilling stuff but is by no means a recent thing. HIV, Zika, Sars and Nipah virus all ‘got their start’ in human populations in this way. We just haven’t learned yet from our previous mistakes.

In the face of global crises of the scale we are now confronting, addressing the ‘front line’ – where we interface with all these diseases and their hosts – might seem an unsurmountable task. But this is not so. Earlier this year, another study by Princeton University showed how spending of about $260 billion over 10 years would substantially reduce the risks of another pandemic on the scale of the coronavirus outbreak. To put that in context, it would be only 2% of the estimated $11.5 trillion costs of Covid19 to the world economy. Not only that, but it would also add huge savings to the costs that will be associated with another global necessity – reducing carbon dioxide emissions and fighting climate change. This is an investment that would not only protect wildlife, habitats and climate but would also save lives.