Blackbirds in Gardens

Help us find out how Blackbirds are doing in your garden and understand why they are declining in some areas.

The Blackbirds in Gardens project will help us understand how Blackbirds use gardens, and the potential effects of the Usutu virus on their population in the UK. 

If you have access to a garden, have an interest in garden birds and can recognise a Blackbird by sight, then this survey could be for you!

This survey will take place from May to October during 2024 and 2025.

The project is part of the Vector-Borne RADAR project run in partnership with the Animal and Plant Health Agency, the UK Health Security Agency and the Zoological Society of London.

Time / skill required

  • As much as you like, but a minimum of 15 minutes per week is recommended.
  • Can identify Blackbirds by sight including reliably separating adult males, adult females and juveniles (guidance provided).
  • A simple identification guide to Blackbirds of both ages and sexes along with some confusion species is provided within the survey data entry web app.

Project Leads
Email Contact

Project timeline, contributions & findings

Project timeline

  • May 2024 - Survey launch
  • October 2024 - End of survey season
  • Winter 2024/25 - Initial reporting
  • April/May 2025 - Survey launch
  • October 2025 - End of survey
  • Winter 2025/26 - Survey reporting

About the project

Blackbirds are a common bird in gardens across the UK, from rural areas to the hearts of cities. However, in recent years and particularly since 2020, birdwatchers have reported fewer birds being seen in their gardens, especially in London.

This recent decline has been linked to the appearance of Usutu virus, a new mosquito-borne virus in the UK which is often fatal to Blackbirds. It was first detected in the UK in London in the summer of 2020, and appears to have since started to spread further in southern Britain. It is prevalent on the near-Continent and its spread has been linked to climate change, which has benefited the mosquitoes which spread the virus.

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.

This survey will help us understand the potential for disease transmission by Blackbirds in gardens by looking at the number of birds that occur together. It will also help us better understand how Blackbird’s use of different types of gardens varies, and how well young can be raised, especially at different levels of urbanisation from rural to urban gardens.

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.

Project partners

This survey is part of the Vector-Borne RADAR project, a partnership between BTO, the Animal and Plant Health Agency (APHA), the UK Health Security Agency (UKHSA) and the Institute of Zoology (IoZ), the research division of the Zoological Society of London (ZSL).