A dead owl in the Delhi zoo has been found to have been infected with bird flu. Officials said the zoo witnessed the death of a brown fish owl in its captivity. Its cloacal, tracheal and ocular swabs were sent to the animal husbandry unit of the Delhi government for serological examination which were found positive for avian influenza virus. As per protocols and guidelines issued by the Centre and the Delhi government, sanitisation and surveillance drills have been intensified in the zoo and all possible preventive measures are being taken. The Delhi zoo has both captive and free-ranging birds, including local migratory waterfowls and waders, in its premises.