Twelve swans have been found dead at Clumber Park raising concerns over the possibility of bird flu.
Government vets are carrying out tests and say they are not making any conclusions until the results have been established.
Management at the National Trust park have urged people to avoid going near wild birds at the park, which has large populations of birds attracted by the lake.
A National Trust spokesperson said: “The bodies of a number of dead swans have been discovered at Clumber Park, Nottinghamshire. A total of 12 swans have been found near the lake at Clumber Park since Christmas eve.
“As a precautionary measure National Trust rangers informed Government scientists, who removed the swan carcasses this week. A post-mortem examination is currently being carried out.
“Clumber Park will remain open to visitors with usual. Public Health England advises that the risks to public health from the H5N8 virus are very low.
“As with any wild animal, we advise our visitors against feeding or touching the ducks, geese and other wild birds at Clumber Park.”