Otters and foxes in Britain are among mammals that have caught bird flu in what is being described as the largest recorded outbreak of the virus, according to the BBC.
Worldwide, the virus has been found in a range of mammals, including grizzly bears in America and mink in Spain, as well as in dolphin and seals.
The BBC reports that figures show the virus has led to the death of about 208 million birds around the world, and there have been at least 200 recorded cases in mammals.
In the UK, the Animal and Plant Health Agency (APHA) has tested 66 mammals, including seals, and found nine otters and foxes were positive for highly pathogenic avian influenza (HPAI) H5N1.
Cases have been found in Durham, Cheshire and Cornwall in England; Powys in Wales; Shetland, the Inner Hebrides and Fife, Scotland.
It is believed they had fed on dead or sick wild birds infected with the virus.
The animals were found to have a mutation of the virus that could make it easier to infect mammals, but there was no evidence of transmission between mammals.
According to the BBC, public health bosses warn that the mutation in mammals could see a jump to humans but the risk to the public is very low.
The UK Health Security Agency (UKHSA) still advises that avian flu is primarily a disease of birds, but experts across the globe are looking at the risks of it spilling over into other species.