Two dolphins have died from bird flu in UK waters for the first time, the government has announced.
The sea mammals were found in separate locations, on beaches in Devon and in Pembrokeshire, last month.
Both dolphins were confirmed to have been infected with the highly infectious H5N1 variant of avian influenza which has spread around the globe during the past 18 months.
Millions of birds have died from bird flu in the latest outbreak, either from the virus itself or from culling, but scientists are concerned that it is spreading to mammals.
The virus has now been confirmed in 23 mammals in the UK. Bird flu has been discovered in dolphins in other parts of the world but these are the first cases in the UK. It has previously been found in foxes, otters and grey seals.
There has not so far been confirmation that the virus can spread between mammals in the wild, and most wildlife who contract avian flu are believed to have caught it from scavenging infected birds.
However there are concerns that H5N1 could potentially be spreading between mammals after the mass deaths of seals and sea lions elsewhere in the world.