- London saw a 50% drop in the capital’s blackbird population in 2020
- The numbers have recovered but are still around 32 percent lower than in 2019.
- Native mosquitoes can transmit the Usutu virus, which was first observed in South Africa
The number of blackbirds in our gardens is plummeting due to a mosquito-borne virus, a charity warns.
The population is falling, notably in London, where the total fell by 50% in 2020, the British Trust for Ornithology (BTO) said.
The numbers have recovered, but are still around 32% lower than in 2019.
The spread of the Usutu virus has been linked to climate change. It was first identified in South Africa before being detected in continental Europe thirty years ago, then in the United Kingdom in the summer of 2020.
Mosquitoes native to the UK can transmit the virus during warmer periods and humans can also catch it, although no cases have been identified in the UK.
Blackbird populations are declining, particularly in London where the total fell by 50% in 2020, according to the British Trust for Ornithology.
Scientists are trying to better understand the extent and spread of the Usutu virus and what its potential impacts could be on the UK’s blackbirds.
The government said the Usutu virus led to the deaths of two people with weakened immune systems in Croatia and Italy.
The BTO added that although the risk was low, “This is the first time in modern history that a mosquito-borne viral zoonosis (a disease that can be transmitted from animals to humans) has appeared in the UK.”
Scientists are now trying to better understand the extent and spread of the Usutu virus and what its potential impacts could be on the UK’s blackbirds.
Researchers want to see if something similar is happening in other major UK cities and how this compares to smaller urban and rural areas.
The BTO is appealing for people to take part in the Robins in Gardens Survey to help their scientists better understand how blackbirds use different types of gardens and what factors might influence the risk of disease transmission .
Importantly, the survey also seeks to determine how successful birds are in raising their young, particularly at different levels of urbanization, from rural to urban gardens.
Dr Hugh Hanmer, senior research ecologist at the BTO, said: “Robin numbers have been declining in Greater London for some time.
“However, from 2020 they started to decline more sharply, which coincided with the detection of the Usutu virus.
“There is now evidence of a greater decline in the south of England, not seen in other parts of the UK.
“The BTO investigation seeks to understand why this change is occurring and identify any links to the emergence of the Usutu virus.
“By better understanding how blackbirds use our gardens, we hope to halt their decline.”
Mosquitoes native to the UK can transmit the Usutu virus during warmer periods and humans can also catch it, although no cases have been identified in the UK.
Blackbird numbers in London fell by 50 percent in July 2020. They have recovered slightly but are still around 32 percent lower today than in 2019.
Dr Arran Folly, APHA Principal Scientist and Vector-Borne RADAR Project Manager, said: “Outbreaks of mosquito-borne diseases, such as the Usutu virus, which is now endemic in South East Australia England, are likely to increase in the UK, particularly as temperatures warm. the wake of climate change.
He added: “I urge all garden owners to get involved and help us track this virus. »
BTO is asking anyone with access to a garden to take part in the survey.
To register, visit www.bto.org/blackbirds-gardens
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