As authorities across the world assess the impact of the global outbreak of bird flu, the crisis has been singled out as the most rapid loss of wild birds in the UK for decades.
James Pearce-Higgins, Director of Science at the British Trust for Ornithology (BTO), said: “The last time we experienced such large-scale and rapid losses of wild birds in the UK would be the impacts of DDT on birds of prey in the 1950s and 1960s associated with the Silent Spring narrative, or the widespread declines of farmland birds during the 1970s and 80s as a result of agricultural intensification.”
Authorities across the world have had to remove dying birds from affected areas (Paul Morrison / RSPB).
His reference to Rachel Carson’s groundbreaking 1962 book compares the impact of avian influenza to that of pesticides including DDT during the 1950s and ’60s. The use of these chemicals killed birds and other animals, and resulted in eggs with shells so delicate they were broken by incubating adults.
Bird flu wreaked destruction across the whole length of the UK in 2022, with seabirds including Northern Gannets and Great Skuas suffering some of the worst impacts. Pearce-Higgins warned that cases among wintering wildfowl already detected this winter do not bode well for 2023, which could see the virus return to seabird colonies.
According to the World Organisation for Animal Health, more than 50,000 wild birds have died of the H5N1 subtype since October 2021. However, it is widely believed that this is only a tiny fraction of the true death toll, with very few infected birds reaching laboratories for testing.
Likewise, the detection of 3,500 cases in wild birds in Europe between 2021 and 2022 will be an underestimate, though the 63 species recorded with the virus provides an indication of the indiscriminate impact of the virus.
Michelle Wille from the University of Sydney said: “Reported numbers are likely a vast underestimate. For example, of the approximate 8,000 Sandwich Terns that died in the Netherlands, only a handful are included in the official numbers – in this case a more than 200x difference between reported numbers and observed. The lack of appreciation for the scale of wild bird mortality is concerning as there may be species- or population-level ramifications.”
UN mapping data shows North America follows Europe in terms of number of reports of bird flu. It has also ripped through bird populations in Africa, Asia and South America, the latter raising concerns that it will reach vulnerable species in the Galapagos.
