The lethal Usutu virus - a mosquito-transmitted illness that has been decimating Blackbirds throughout southern England, is causing concern among wildlife specialists.
First identified on British territory in 2020, the virus has subsequently spread westward into Dorset and expanded northward to Cambridgeshire. Originating from Southern Africa, Usutu reached Europe three decades ago, where it has caused several catastrophic Blackbird population collapses, according to Bird Guides.
The British Trust for Ornithology is currently encouraging all garden owners with blackbirds to take part in a specialist survey to evaluate the extent of the damage and offer support where needed - however, only days remain to participate as it concludes in early September.
While the threat to humans remains low - with zero confirmed cases in Britain - the impact on bird populations is catastrophic. Data reveals that throughout Greater London, Blackbird populations have plummeted by as much as 40% since Usutu's emergence following the 2020 heatwave.
Dr Arran Folly from the Animal and Plant Health Agency (APHA) issued warnings regarding the virus's rapid spread and continued presence, suggesting it could foreshadow other mosquito-borne diseases arriving in Britain. "It gives an indication that in the future we might get other viruses that are transmitted by mosquitoes emerging in the UK," he cautioned, reports the Express.
Attributed to climate change, mosquito population booms are being fuelled by rising temperatures, prolonged summers, and increased rainfall - establishing ideal conditions for both the insects and their lethal diseases to flourish in areas where they previously couldn't survive.
Joining forces with the British Trust for Ornithology (BTO), APHA researchers intend to examine Usutu's catastrophic impact on our indigenous bird species more comprehensively.
Meanwhile, the BTO is appealing to Britons to assist in monitoring the crisis by documenting Blackbird observations.
"Blackbirds are currently nesting and are a common sight in gardens and parks. With public help, we can better track population trends and the virus's impact," a BTO spokesperson declared.
Whilst Blackbird populations remain steady in rural and northern areas, the unpredictable character of the virus requires continuous surveillance.
The joint endeavours of APHA and BTO aim to provide essential data to inform conservation strategies and prepare for future emerging diseases.
The BTO revealed: "We are trying to better understand the extent and spread of Usutu virus and what the potential impacts of the virus might be on Blackbirds. In particular, as Blackbird numbers were already decreasing in London, a large urban area, we want to know if anything similar is happening in other urban areas, or whether these changes are specific to the capital, and how this compares to smaller urban and more rural areas."
The British Trust for Ornithology (BTO) is carrying out research to assess the potential for disease transmission by Blackbirds in gardens, studying the number of birds that gather together.
The organisation explained it will help understand how Blackbird usage of different garden types differs, and how effectively young can be reared, particularly at varying degrees of urbanisation from countryside to city gardens.
The BTO cautioned: "Although largely harmless to humans, this is the first time in modern history that a mosquito-borne viral zoonosis (a disease which can be transmitted from animals to humans) has emerged in wild animal hosts in the UK but, with changing climates, more may occur in the future.
"Using Usutu virus and Blackbirds as a case study, this survey is part of the Vector-Borne RADAR project, a wider partnership project funded by the UKRI and Defra to understand the emergence and transmission of mosquito-borne viruses in the UK more generally which are expected to increase with climate change.
"The project will improve understanding of how these viruses emerge in new environments, enhance surveillance of diseases in wild birds in the UK and develop an early warning system for disease outbreaks."