The deadly H5N1 bird flu strain is feared to be behind the death of two owls in a Dutch zoo, Radio Netherlands reported Monday.
Tests are being carried out after two young hawk owls died last week in a Rotterdam's Blijdorp zoo. Two other owls were destroyed by the zoo.
If the tests prove the existence of the H5N1 virus, it would be the first case of H5N1 in the Netherlands.
The four hawk owls were born in May, just after all the birds in the zoo were vaccinated against bird flu, said Radio Netherlands.
As a precaution, all the birds at Blijdorp are being kept indoors and the staff have taken virus inhibitors.