Despite the ongoing threat of bird flu, the Egg Producers Federation says free-range chickens are likely to move in and out of temporary lockdowns over the coming months as farmers respond to changing risk levels.

Hundreds of thousands of hens have been kept indoors following the confirmation of a third case of bird flu in a wild bird in New Zealand. However, Egg Producers Federation Chair and Mainland Poultry Chief Executive John McKay said around 500,000 of Mainland Poultry's hens would be allowed back outside on Wednesday.

Speaking to Checkpoint, McKay said farmers now have access to sufficient data to assess the level of risk to their flocks and make informed decisions about whether hens can safely resume free-ranging.

As a precaution against bird flu, many egg producers capable of doing so have temporarily housed their hens indoors, limiting their ability to roam freely. McKay said the latest information suggests the risk to chickens remains low, even after the third detection of the virus.

"The latest case was found in a petrel, and it's likely that we will continue to occasionally find infected seabirds washing up on our shores," he said.

Mainland Poultry decided on Tuesday to prepare its farms for the return of hens to outdoor areas from Wednesday morning.

"This is an evolving situation, and we will continue monitoring it closely and assessing the risks. The welfare of our birds remains our highest priority. If the risk level changes in the future, we may need to bring the birds back indoors again," McKay said.

He warned that temporary restrictions on free-ranging could become a regular feature of poultry farming in New Zealand if bird flu continues to pose a threat.

"We are committed to free-range farming because we want our birds to have access to the outdoors, and our customers care deeply about animal welfare," he said.

To reassure consumers about the status of their eggs during future lockdown periods, McKay said Mainland Poultry plans to place stickers on egg cartons whenever hens are temporarily housed indoors. The labels will clearly explain that the birds were kept inside for their own protection and welfare.

"It will be clear communication," McKay said. "We're also helping consumers understand how farmers are managing these risks while continuing to prioritise the health and welfare of their birds."