Housing measures are now in place in NI as part of the Avian Influenza Prevention Zone. This is in addition to measures in place for England, Scotland and Wales. All bird keepers now legally required to house their birds or take measures to prevent them mixing with wild birds. Review your Biosecurity requirements HERE.
For birds such as ducks and geese, where housing is less practicable due to welfare concerns, you must fully enclose them, e.g. with netting to separate them from wild birds.
There are certain species of birds which would be very difficult to house or net, such as large commercial flocks of geese and gamebirds. If it is impossible for you to house or enclose your birds then you must feed and water your birds undercover, fence off and net ponds and standing water and take active methods to separate them from wild birds. See the full requirements in the Avian Influenza Prevention Zone declarations: