A wild swan found dead in County Londonderry has tested positive for bird flu.
It was discovered at Lough Beg near Toomebridge earlier this week.
Preliminary results confirmed that it had a similar strain of the disease to that found in poultry flocks and wild birds in Britain.
Public health officials have advised that the risk to public health from this strain of avian influenza is very low, as is the risk to food safety.
A dead falcon in County Limerick also tested positive in recent days.
The chief vet Dr Robert Huey urged poultry keepers to tighten their biosecurity measures to stop transmission to commercial flocks.
The swan was found by environmentalist Chris Murphy who was assessing the impact of A6 roadworks on overwintering birds at the lough – an internationally important protected site.
Further tests will now be carried out to establish whether the disease is a highly pathogenic strain, or one which is less virulent.
A bird flu prevention zone was declared across Britain on Wednesday after the discovery of the disease there.
Where it is detected in poultry flocks the birds are destroyed and prevention zones are established around affected premises.
It can also lead to restrictions on trade.
Northern Ireland’s Chief Vet Robert Huey urged anyone with poultry to tighten their biosecurity to prevent interaction between wild birds and their flocks.