Why London’s blackbirds are dying

Blackbirds. Some people think they are a bad omen (well, when counted among ‘black birds’), others love to listen out for their sweet song – they are widely acknowledged to be one of the most melodious songbirds in the UK. 

Whether you love them or hate them, the sad truth is that blackbirds are on the decline in Britain. Scientists are concerned about the plummeting numbers of the birds across London and the south of England, and they are disappearing for a pretty grim reason. 

The shrinking blackbird population has been linked to a new mosquito-borne virus that was detected in the UK in 2020. The Usutu virus, which can be fatal to blackbirds, was first identified in South Africa. It’s been present in mainland Europe for about 30 years, but only reached Britain five years ago. 

Scientists say that increasing temperatures due to climate change have allowed the virus to spread more quickly, as mosquitos can transmit it during hot weather. A 2024 survey found that blackbirds were doing well in the north of England, but struggling in London and the south-east of England. 

Now researchers from the British Trust for Ornithology (BTO) are now asking for the public’s help. Anyone with a garden can take part, and you can do your bit by taking part in a survey of blackbirds online here.

‘Blackbird numbers have been noted to be decreasing in Greater London for some time. However, from 2020 they started declining more strongly, which coincided with the detection of Usutu virus, which can be fatal for these familiar birds,’ says Hugh Hanmer, senior BTO ecologist, told BBC Countryfile.

‘This survey seeks to understand why this change is happening and if it is linked to the spread of Usutu by better understanding how blackbirds use our gardens.’ 

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