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Usutu virus linked to 39% drop in London blackbirds in four years

Friday, 16 May 2025 12:20AM UTC

A mosquito-borne disease called the Usutu virus is causing dramatic declines in blackbird populations across southern England. Scientists warn that warmer temperatures fuel the virus's spread, prompting urgent calls for garden surveys and conservation action to protect the beloved songbirds.

A mosquito-borne disease known as the Usutu virus has recently made headlines in the UK, particularly concerning its impact on local blackbird populations. Since its identification in 2020, the virus has spread rapidly throughout southern England, generating significant concern among scientists and conservationists alike. This worrying trend coincides with observed declines in blackbird numbers, prompting urgent calls for monitoring and action.

It is estimated that blackbird populations in Greater London have plummeted by approximately 39% over the past four years, with the Usutu virus playing a pivotal role in this decline. The virus, which is transmitted by mosquitoes, poses not only a biological threat to these beloved songbirds but also signals broader ecological challenges associated with climate change. Warmer temperatures are creating more favourable conditions for mosquitoes, which could further enable the virus to spread rapidly across the UK.

In response to the escalating situation, the British Trust for Ornithology (BTO) has launched the "Blackbirds in Gardens" project. This initiative invites individuals with gardens to participate in a survey aimed at collecting vital data on blackbird populations and their interactions with the environment. Dr Arran Folly from the Animal and Plant Health Agency (APHA) emphasised the importance of this project, stating, "We've seen that the virus has spread further than we thought it might do, and it's persisted." The involvement of local residents will help researchers gain insights into how the Usutu virus is affecting blackbird habits and survival rates in urban settings.

The urgency of this project is also highlighted by government evaluations, which indicate a low to moderate risk of human transmission of the virus. While the Usutu virus is unlikely to lead to widespread human infection, it has severe implications for bird populations. According to a study published in the journal Emerging Infectious Diseases, similar viruses have previously been linked to significant population declines among birds in Europe, including a 15.7% drop in common blackbird numbers in affected areas.

As the Usutu virus continues to spread, the onus is not only on scientists and policymakers but also on the public. The BTO encourages garden enthusiasts to participate in the survey and help raise awareness. Adjustments to garden ecosystems, such as removing stagnant water sources that serve as mosquito breeding grounds, might also mitigate the risk of further outbreaks.

Conservation efforts, both local and nationwide, must now pivot to include thorough monitoring and proactive measures against the threat posed by the Usutu virus. As scientists investigate the interplay between climate change and disease emergence among wildlife, the call for community engagement has never been more vital. Understanding the full impact of this viral threat will require a multidisciplinary approach, with the goal of protecting both blackbirds and the biodiversity they represent within our gardens and ecosystems.

The implications of the Usutu virus extend beyond just the plight of blackbirds; they serve as a cautionary tale about the fragility of wildlife in the face of rapid environmental change. As we witness the reverberations of climate change manifest across species and habitats, the welfare of our natural world hangs in a delicate balance, highlighting the urgent need for informed action and conservation efforts.

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Source: Noah Wire Services

More on this

https://www.express.co.uk/news/nature/2055485/anyone-blackbirds-garden-asked-scientists-take-action-now - Please view link - unable to able to access data
https://www.gov.uk/government/publications/hairs-risk-assessment-usutu-virus/hairs-risk-assessment-usutu-virus - The UK government's HAIRS risk assessment evaluates the Usutu virus, a mosquito-borne flavivirus first recognized in Europe in 2001. The assessment indicates that while human infection is possible, it is unlikely to be extensive, with a low to moderate impact on higher-risk groups. The report emphasizes the need for monitoring the situation in European countries for increasing reports of human cases or changes in pathogenicity of human infections. It also recommends raising public awareness on mosquito bite prevention measures, particularly in known risk areas.
https://www.theguardian.com/environment/article/2024/jul/03/blackbird-numbers-plummet-in-south-of-england-amid-potential-spread-of-virus - An article from The Guardian reports a significant decline in blackbird populations in Greater London and southern England, attributed to the spread of the Usutu virus. The virus, first identified in the UK in 2020, is believed to be spreading across southeast England. The decline in blackbird numbers is linked to climate change, which allows native UK mosquitoes to transmit the virus during warmer periods. The article highlights the need for further research to understand the factors contributing to the decline and potential conservation efforts.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5708248/ - A study published in the journal Emerging Infectious Diseases examines the distribution of the Usutu virus in Germany and its effect on breeding bird populations. The research found that the virus led to a 15.7% additional decline in common blackbird populations in areas suitable for USUV circulation. The study underscores the threat posed by the emergence of USUV to bird populations in Europe and the need for further research to understand its impact on ecosystem services provided by birds, such as seed dispersal.
https://www.standard.co.uk/news/london/blackbirds-numbers-fall-mosquito-virus-usutu-b1208062.html - An article from The Standard reports on the continued decline of blackbird numbers in London due to the spread of the Usutu virus. The virus, first detected in South Africa, has been impacting UK blackbird populations since its identification in London in 2020. The article highlights the spread of the virus to areas like East Anglia and Dorset, raising concerns about blackbird numbers in southwest England. Ecologists are calling on gardeners to help reduce the spread of the virus by making minor adjustments to their gardens.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9206397/ - A study published in Scientific Reports combines host and vector data to assess the emergence and potential impact of the Usutu virus outbreak in UK wild birds. The research found regional clustering of blackbird disease incident reports and a reduction in the frequency of blackbird sightings in gardens near the index site in 2020, suggesting a disease-mediated population decline. The study emphasizes the importance of combining multidisciplinary surveillance to detect and assess the impact of future disease emergence events in wildlife.
https://www.itv.com/news/2024-06-03/blackbirds-under-threat-from-deadly-usutu-disease-how-you-can-help-save-them - An ITV News report highlights the threat to blackbirds from the Usutu virus, a mosquito-borne disease affecting UK blackbird populations. The virus, first detected in South Africa, spread to Europe in the mid-90s and arrived in London in 2020. The report notes a 39% decline in blackbird numbers in London over the past four years. The British Trust for Ornithology has launched the 'Blackbirds in Gardens' survey to map the spread of the virus and understand its impact on blackbird populations.

Noah Fact Check Pro

The draft above was created using the information available at the time the story first emerged. We’ve since applied our fact-checking process to the final narrative, based on the criteria listed below. The results are intended to help you assess the credibility of the piece and highlight any areas that may warrant further investigation.

Freshness check

Score: 8

Notes: The narrative references recent events and ongoing studies, such as the Usutu virus's impact since 2020 and current conservation efforts. However, some details might be based on older research or similar press releases.

Quotes check

Score: 6

Notes: The quote from Dr Arran Folly could not be verified as an original source online. It appears to be specific to this context but lacks a clear origin.

Source reliability

Score: 7

Notes: The narrative originates from The Express, a publication known for mixed reliability. It cites reputable organizations like the British Trust for Ornithology and references government evaluations.

Plausability check

Score: 8

Notes: The claims about the Usutu virus affecting blackbird populations are plausible, given the context of climate change and mosquito-borne diseases. However, some specific figures or outcomes might require further verification.

Overall assessment

Verdict (FAIL, OPEN, PASS): OPEN

Confidence (LOW, MEDIUM, HIGH): MEDIUM

Summary: The narrative appears to be based on recent events and includes plausible claims about the Usutu virus's impact on blackbirds. However, the reliability of specific figures and the quote's origin are uncertain. Overall, it requires further verification to fully assess its accuracy.

Usutu virus
blackbirds
conservation
climate change
British Trust for Ornithology