Mosquito-borne disease that has recently arrived in the UK has widened a lot of distance, and scientists compete to understand the risks of wild birds.

Infected insects can spread the deadly Usutu virus to the blackbirds, causing fear of famous songs.

New data shows that USUTU has spread across much of southern England in five years and is associated with a decline in the population of some Blackbirds.

Scientists are monitoring its spread because they warn mosquitoes and the diseases they carry may expand in the context of climate change.

"We have seen that the virus spread farther than we thought and continues to exist," Dr. Arran Folly from the Animal and Plant Health Agency (APHA) told the BBC.

Scientists at Apha in Saribridge have been tracking mosquito-borne diseases in wild birds for decades, warning that climate change turns Europe into a potential breeding ground for insects.

Longer summers, higher temperatures and heavy rains are bringing nuisance insects into areas that were previously unhappy for them.

Until 2020, all results have recovered. Then, after the summer heat wave of that year, Usutu was found among several black birds in Greater London.

"Blackbirds are particularly vulnerable to the virus, and since 2020, we have seen a decline in the number of blackbirds in Greater London by about 40 per cent," Dr Folly said.

“This suggests that in the future we may get other mosquito-borne viruses that are emerging in the UK.”

Among many other stresses, including habitat loss, climate change and pesticide use, diseases such as USUTU are growing threats to wild birds.

• More than half a century ago, the USUTU virus was first discovered around the Usutu River in southern Africa.

• Since then, it has spread all over the world, arrived in Europe thirty years ago and was first received in the UK in 2020

• Blackbirds are particularly susceptible to the virus, which can also infect horses and infect humans from time to time.

The latest data show that USUTU spread farther than scientists expected.

It has now been found in wild birds in most parts of southern England, at least west to Dorset and north to Cambridgeshire.

How risky Usutu is for wild birds is uncertain. The virus is linked to the massive deaths of blackbirds elsewhere in Europe, although this does not seem to be the case in the UK.

Blackbirds remain one of the most common garden birds, and in many parts of the country, especially in rural areas and in the north, have stable populations.

To solve the puzzle and collect more data on the Blackbird’s numbers, scientists have teamed up with the UK’s Ornithology Trust (BTO).

They called on volunteers to count the blackbirds in the garden during the summer months to learn more about the breeding and behavior of the birds.

Now around the summer evening, black birds are breeding and raising their young, often seen singing along the branches and singing from the branches.

Lucy Love is BTO's garden bird watching ambassador, seeing the blackbirds in her garden and having become more and more fond of them.

"They are beautiful birds - smart, friendly, they have the most beautiful songs with lovely melodic tones," she explained.

“And we can’t lose them – they are an important part of our ecosystem.”