Experts believe the songbird is suffering from Usutu virus, first detected in UK in 2020. The decline of the bird, particularly in the South East, is being looked at by the British Trust for Ornithology who are asking members of the public to help them by completing a survey.

paid tribute to by Shakespeare and the Beatles, the blackbird and its song have held people in rapture for centuries.

The Usutu virus was first detected in the UK in London in summer 2020. This disease is potentially fatal to blackbirds and is thought to be spreading across south-east England. It was first identified in South Africa and has spread across mainland Europe. Native UK mosquitoes can transmit the virus when it is warm outside.

Blackbird numbers in the south fell 50% in 2020 compared with 2019. Numbers recovered somewhat, but are still about 32% lower now than in 2019. Overall, their numbers have decreased by 18% UK-wide since the 1970s due to factors including habitat loss.

Dr Hugh Hanmer, a senior research ecologist with BTO, said: “Blackbird numbers have been decreasing in Greater London for some time. However, from 2020 they started declining more strongly, which coincided with the detection of Usutu virus. There is now evidence of a wider decline in southern England, not seen in other UK regions.

“The BTO survey seeks to understand why this change is happening and to identify any link to the emergence of Usutu virus. By better understanding how blackbirds use our gardens, we hope to halt the declines.”

Researchers want to see if there are similar patterns in other large cities in the UK and if there are differences between rural and urban areas.

It is hoped the survey will help BTO scientists better understand how blackbirds use different types of garden, how successful birds are at rearing young, which factors may influence the risk of disease transmission and how all these factors differ at different levels of urbanisation.

Blackbirds are widely loved because of their complex song, which is very mellow and almost sounds as if it is in a major key. They deliver low-pitched, flute-like verses and are able to mimic each other, and other birds.

The BTO survey is open until October. You can find out more about it and how to take part here

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