Six chickens have tested positive for bird flu after they died suddenly.
The discovery means a new 3km protection zone will be enforced in the Mont Felard area.
All poultry keepers are encouraged to house their birds to make sure they are kept separate from all other commercial, domestic and wild birds, though this isn't yet a legal requirement.
Other bird keepers outside the two exclusion zones are highly encouraged to house their birds too, as well as register their flock with the government.
Anyone with a flock of more than 30 birds is already legally required to register, but the States Deputy Chief Vet Caroline Terburgh says registering means bird keepers can be kept up to date 'on bird flu outbreaks and guidance on how to best look after your flock.'
Islanders are encouraged not to touch dead or sick birds but to report them by calling 441600.

Phone robber jailed after targeting a 'lone' woman
Channel Islands' parliamentary Standards Commissioner resigns
Island Energy charged over Mont Pinel gas explosion
Jersey airport to open early due to broken scanner
Critically endangered species of lemur joins Jersey Zoo
Lido to 'pause trading' amid ongoing uncertainly
Ports of Jersey applies to remove Gorey Pier landing stage
Jersey's police officers to be held to new standards